Sexual Patterns in the Labroid

Fishes of the Western Caribbean, I:

The Wrasses (Labridae)

ROBERT R. WARNER

and

D. ROSS ROBERTSON

m

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 254
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SMITHSONIA N CONTRIBUTION S T O ZOOLOG Y • NUMBE R 25 4

Sexual Patterns in the Labroid

Fishes of the Western Caribbean, I:

The Wrasses (Labridae)

Robert R. Warner

and D. Ross Robertson

SMITHSONIAN INSTITUTION PRESS

City of Washington

1978
ABSTRAC T

Warner, Robert R., and D. Ross Robertson. Sexual Patterns in the Labroid

Fishes of the Western Caribbean, I: The Wrasses (Labridae). Smithsonian Contributions to Zoology, number 254, 27 pages, 11 figures, 7 tables, 1978.—We report

here on the results of a two year investigation into the interactions of sex change,

coloration, and mating behavior in nine Caribbean wrasses (Bodianus rufus,

Halichoeres bivittatus, H. garnoti, H. maculipinna, H. pictus, H. poeyi, H. radiatus, Clepticus parrae, and Thalassoma bifasciatum). For each species, we outline

(1) the distribution of sexual types according to size and coloration, (2) the testis

weights of different types of males, (3) characteristic habitat and relative abundance, (4) the social and mating system, and (5) breeding seasonality. In all dichromatic labrid species, sex change from female to male appears to precede a change

of coloration into the bright terminal phase. Two wrasses (B. rufus and C. parrae)

that lack non-sex-changed (primary) males have mating systems in which terminal

phase males can effectively control the spawning of the females. Other labrid

species have lek-type mating systems, within which small primary males interfere

in the spawnings of large terminal males. This activity is reflected in the high

testis weight of these small males, who face sperm competition in mating. There

is a general correlation between population density (measured by relative abundance) and frequency of primary males.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded

in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea

cavernosa (Linnaeus).

Library of Congress Cataloging in Publication Data

Warner, Robert R.

Sexual patterns in the labroid fishes of the western Caribbean.

(Smithsonian contributions to zoology ; no. 254)

Bibliography: p.

Contents: I. The wrasses (Labridae).

1. Wrasses—Behavior. 2. Sexual behavior in animals. 3. Fishes—Behavior. 4 Fishes—Carib

bean Sea. I. Robertson, D. R., joint author. II. Title. HI. Series: Smithsonian Institution.

Smithsonian contributions to zoology ; no. 254.

QL1.S54 no. 254 [QL638.L12] 591'.08s [597'.58] 77-608142
Contents

Page

Introduction 1

Acknowledgments 2

Materials and Methods 2

Species Studied 2

Study Area 2

Collecting 2

Terminology 2

Coloration 3

Sexuality 3

Mating Patterns 3

Determination of Population Parameters 4

Results 5

Bodianus rufus 5

Halichoeres bivittatus 5

Halichoeres radiatus 8

Halichoeres garnoti 8

Halichoeres maculipinna 9

Halichoeres pictus 10

Halichoeres poeyi 11

Clepticus parrae 12

Thalassoma bifasciatum 13

Discussion 15

Patterns of Population Structures and Their Relationship to Life Histories 15

Labrid Life History Patterns 15

Diandric Species 15

Monandric Species 16

Significance of Testis Size in Relation to Reproductive Strategies 16

Mating Systems and the Reproductive Success of Initial Phase Males ... . 17

Appendix 1: Definition of Terms 21

Appendix 2: Terminology Applied to Labroid Color Phases 22

Appendix 3: Tables 23

Literature Cited 26

in

Sexual Patterns in the Labroid

Fishes of the Western Caribbean, I:

The Wrasses (Labridae)

Robert R. Warner

and D. Ross Robertson

Introduction

Fishes are exceptional among the vertebrates in

that many of them change sex during their adult

lives (Atz, 1964; Reinboth, 1970; Warner, in press).

The change can either be from female to male

(protogyny) or the reverse (protandry). In the few

protogynous species whose social systems have been

studied in detail, the females mate chiefly with

larger, older males (Robertson, 1972; Robertson and

Choat, 1974; Warner, Robertson, and Leigh, 1975).

This factor of strong sexual selection often leads to

sexual dimorphism, with males developing specialized structures and colorations for combat and display.

Intense sexual selection also creates large differences in the age-specific fecundity patterns between

males and females and this leads to selection for

sex change. These differences are to the reproductive advantage of individuals that change sex at

a certain time, e.g., females that change into males

when they become large enough to compete successRobert R. Warner, Department of Biological Sciences and

Marine Science Institute, University of California, Santa

Barbara, California 93106. D. Ross Robertson, Smithsonian

Tropical Research Institute, P.O. Box 2072, Balboa, Canal

Zone.

fully for females (Robertson and Choat, 1974;

Warner, 1975a). They are thus the right sex at the

right size. Many of the protogynous species also

contain small males that are colored like females

and that employ a mixture of mating strategies different from those of the large, brightly colored, and

often territorial males (Warner, Robertson, and

Leigh, 1975).

The interrelation of mating system, sex change,

and sexual dichromatism can be exceedingly complex. Labroid fishes (including the wrasses, family

Labridae, and parrotfishes, family Scaridae), most

of which are protogynous, present a good example

of the wide diversity of sex and coloration patterns

that can exist. Most labroids are found in the shallow, warm seas of the tropics. They tend to mate

the year round, in specific areas. Thus the details

of their life histories and behavior can be easily

observed by a diver.

Since the pioneering work on protogyny in tropical and subtropical labroids by Reinboth (1957,

1962, 1967, 1968, 1970, 1973), there have been two

major efforts at systematically examining the sexual

patterns of a series of labroid species. Choat (1969)

studied a large number of western Pacific (Great

Barrier Reef) wrasses and parrotfishes (published

in part in Choat and Robertson, 1975). Roede
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

(1972) detailed sex and coloration in seven Caribbean labrids, but did not distinguish between primary and secondary (sex-changed) males (terminology detailed below).

In this paper and the one following (Robertson

and Warner, 1978) * we describe the patterns of sex,

coloration, and mating behavior for most of the

Caribbean labroids. We have done this in part to

test our ideas on (1) how sexual selection can act

as a cause for sex change, and (2) how non-sexchanging males can coexist with sequential hermaphrodites. Basically we expect few small males in

species where low effective population density allows large, dominant males to control most of the

spawning (for details of these arguments, see Warner, Robertson, and Leigh, 1975). We have found

some consistent patterns among the species that

lend support to our expectations, but there are

several species with apparent anomalies and unexpected distributions of sex and coloration. We have

offered explanations for many of these anomalies

and modified our hypotheses accordingly. Others

remain a mystery to us and stand as suggestions for

future research in tropical marine biology.

ACKNOWLEDGMENTS.—We would like to thank

the government of the Republic of Panama and the

Cuna Indians of the Comarca de San Bias for permitting us to live and work in the San Bias Islands.

Funds and facilities generously supplied by Smithsonian Tropical Research Institute (STRI) and the

Australian Commonwealth Scientific and Industrial

Research Organization (CSIRO) enabled us to do

this work: Robert R. Warner during his tenure as

a STRI postdoctoral fellow and D. Ross Robertson

as a CSIRO post-doctoral student visiting STRI.

Additional funds were provided by the National

Geographic Society and a general research grant

from the University of California, Santa Barbara

(UCSB); the Marine Science Institute at UCSB

aided us with clerical help and computer funds. The

assistance of Isabel Downs and Elisabeth Fletcher

in the field and laboratory was invaluable. Isabel

Downs also drew the figures and provided technical

aid and advice. We were also assisted in the field

by S. Hoffman, D. Diener, N. Davis, G. Irvine,

J. Bryan, and S. Cruz. A. W. Ebeling and R. H.

Rosenblatt read the manuscripts and provided helpful comments.

• Order of authorship was determined by the flip of a coin.

Materials and Methods

SPECIES STUDIED.—We were able to obtain enough

specimens to examine in reasonable detail the following eight shallow-water species: Bodianus rufus,

Halichoeres bivittatus, H. garnoti, H. maculipinna,

H. pictits, H. poeyi, Clepticus parrae, and Thalassoma bifasciatum. An interesting but less complete

sample of Halichoeres radiatus was also collected.

Of the remaining six shallow-water species listed by

Randall (1968), we very infrequently observed

Lachnolaimus maximus, Doratonotus megalepis,

Hemipteronotus splendens, and H. marlinicensis.

STUDY AREA.—All specimens were collected and

all observations made on the reefs in the Archipie"lago de San Bias off the Caribbean coast of

Panama. Within this general area our operations

were restricted to the western limits of the archipelago, i.e., to no more than 50 kilometers east of

the Peninsula de San Bias.

COLLECTING.—Collecting and field observations

were spread throughout the year during both the

wet and dry seasons (see Glynn, 1972) from March

1974 to May 1975.

In many species of labrids, periods of sexual

activity are characterized by mass migrations of

individuals to particular sites on reefs, where they

assemble in sex-specific groups. Therefore we did

not make collections at such times in order to

increase the chances of random sampling with

respect to sex in each size class. Specimens of

Halichoeres bivittalus and Thalassorna bifasciatum

were collected in a lift net as figured in Roede

(1972). These and the other small species were also

collected using a small, multipronged spear in a

simplified Hawaiian sling. Large Bodianus rufus

and Clepticus parrae were taken with a small multipronged speargun.

TERMINOLOGY.—The profusion of color patterns

and sexual types that occur among the labroid fishes

has been a source of problems both to taxonomists

and ichthyologists in general. Closely related species

are often morphologically very similar, except in

their color patterns. Although it has long been

known that some species in each family are sexually

dichromatic (Longley, 1914; Lonnberg and Gustavson, 1937; Longley and Hildebrand, 1941) a realization of just how common intraspecific polychromatism is in these groups really only began about

twenty years ago. At that time investigators began
NUMBER 254

to examine population structures, to experiment

with inductions of sex and color phase changes,

and to make field observations on social groupings

and spawning activity (Brock and Yamaguchi, 1954;

Randall, 1955, 1963; Bacci and Razzauti, 1958;

Strasburg and Hiatt, 1957; Winn. and Bardach,

1957, 1960; Schultz, 1958; Sordi, 1962; Randall and

Randall, 1963).

Because interest in the reproductive biology of

the wrasses and parrotfishes has expanded rapidly,

and the number of people engaged in research on

it has grown, a variety of synonyms for the different

color phases, sexual types, and mating behaviors

has come into use. This has begun to complicate

communication so that standardization of terms

seems necessary. We discuss the terms used in these

papers below, and summarize our definitions in

Appendix 1.

Coloration: Within many labroid species there

exist several distinct, relatively permanent color

patterns. Individuals may also exhibit rapid, temporary, and sometimes radical color changes. In

this study we are interested primarily in examining

the distribution of different color patterns with

respect to sex and size in each species. In labroids

there is often a recognizable dichotomy in the color

patterns shown by adult fishes, with a predictable

change from one pattern to the other as the animal

ages. Some of the terms that have been used in the

past for the juvenile and adult color phases are

shown in Appendix 2. We follow the scheme used

previously (Randall, 1968; Reinboth, 1973, 1975;

Warner, Robertson, and Leigh, 1975) in referring

to the pattern shown by the smallest adults as the

initial pattern and that shown by the largest adult

males as the terminal pattern. Fishes with these

patterns are then in the initial and terminal color

phases. When immature individuals show coloration different from that of small adults, it is termed

the juvenile color pattern. To some extent, this is a

convenient oversimplification, since variability often

exists, particularly in the initial pattern (see Roede,

1972). Also for convenience, we classified individuals

in the process of changing color as being in terminal

phase. We support the continued use of juvenile,

initial adult, and terminal adult for the three possible basic phases for the following reasons: (1) they

are simple and etymologically self-explanatory; (2)

they are functional since they refer to major, dis-.

tinct phases in the animal's life history (further

splitting seems of less obvious value); and (3) they

are in common usage.

The terms sexual dichromatism and monochromatism have long been used in the same manner as

we will use them here. In monochromatic species,

females are capable of developing all the same patterns as males. In dichromatic species, females cannot do so, and all the fishes of one color phase are

definitely known to be males. Two types of dichromatism can be distinguished on the basis of whether

or not the terminal pattern has any color elements

that the initial pattern does not have: with full

dichromatism some of the elements are present only

in the terminal pattern, whereas with partial dichromatism the same elements are common to both patterns, but some are much more strongly developed

in the terminal pattern. Dichromatic species can

also be divided into two different categories depending on the permanence of the terminal coloration:

in temporarily dichromatic species, terminal phase

fish can revert to the initial pattern, whereas they

cannot do so in permanently dichromatic species.

Sexuality: Reinboth's work on protogyny in

the labroid fishes (Reinboth, 1957, 1962, 1967, 1968)

led to his discovery that, ontogenetically, there were

two types of males, those born as such (primary

males) and those resulting from sex changes in

females {secondary males). The data herein, however, and that of Choat and Robertson (1975) on

parrotfishes indicate the need for making a further

distinction between those hermaphroditic males that

function as females before they change sex (postmaturational secondary males) and those that

"change" before they have matured as females (prematurational secondary males). Harrington (1971)

termed the latter false male gonochores.

If a species contains both primary and secondary

males, it is diandric (Reinboth, 1967). When the

only males present are secondary, it is monandric.

In species that have both secondary and primary

males, the proportion that are of the latter type

varies considerably (Choat and Robertson, 1975,

and data herein). The existence of non-sex-changing

females contributes added complexity. We term

these primary females, to distinguish them from

hermaphroditic females, and to show that they are

analogous to primary males. At least one species

of wrasse appears not to be hermaphroditic (Diener,

1976).

Mating Patterns: We outline the structure of
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

the social and mating systems of many of the

species, based on field observations. A broad distinction may be made between species that mate

in leks and those that mate in harems. Leks are

formed when males tend to concentrate at traditional sites, each defending a small area against

the intrusions of other males. Females also gather

at this area and generally spawn with one of the

competing males. Territoriality is temporary in

lekking species, lasting only for the duration of the

spawning period.

Males maintaining harems are permanently territorial. Their territories contain a group of females

with whom the dominant male mates almost exclusively. More complete descriptions of a harem

species can be found in Robertson (1972) and of

a lekking species in Warner, Robertson, and Leigh

(1975). We generally make distinctions between

pair spawning, where a single male mates with a

single female, and group spawning, where a number

of males fertilize the eggs of one female. This latter

type of spawning is often characteristic of small,

initial phase males. These small males may also

remain close to the territory of a larger male and

individually steal spawnings with females who are

waiting to spawn with larger males (sneaking), or

join the large male and the female at the climax

of spawning (streaking; see Warner, Robertson,

and Leigh, 1975).

DETERMINATION OF POPULATION PARAMETERS.—

We present data on the degree of sexual dichromatism of each species and on the relationship of the

color phases to sex and size. Using data gathered

both from collections of specimens and from field

observations, we also measure the degree of overlap

in the size ranges of the initial and terminal phases

in the dichromatic species. The ratio of the number of initial phase fish to terminal phase fish was

estimated by counts made outside spawning periods.

Some bias probably arises as a result of the terminal phase being characteristically more strikingly

colored, and thus being more visible to the observer.

The sex of specimens could often be determined

macroscopically, by observing the release of gametes,

color and general appearance of the gonad, and, in

unripe females, by the presence of maturing eggs.

The sex of inactive specimens was determined histologically. Primary and secondary males in each

species were differentiated histologically using criteria laid down by Reinboth (1962). For each species,

we were able to determine (1) if both primary and

secondary males were present in a species (diandry),

or only secondary males (monandry), (2) the size/

frequency distribution of both types in terminal

and and initial color phases, and (3) the distribution in the population of secondary males in the

process of sex change.

Ripe individuals were defined as those emitting

gametes when stimulated with a little finger pressure on the belly, active females as those with

vitellogenic oocytes, and inactive females as those

with only previtellogenic oocytes. Secondary males

whose gonads contained many previtellogenic oocytes

or degenerating oocytes were classed as transitional.

In other labroid fishes there are radical differences in the sizes of the testes of males in different

color phases (Robertson and Choat, 1974; Choat

and Robertson, 1975). Therefore, the testis weight

of males in the various labrids was considered in

relation to the color phase and sexual derivation

of the male.

Breeding seasonality was determined from observations on spawning in different months and collections of ripe females at various times. The adult

sex ratio of each species was estimated from a

combination of the sex ratio of individuals in each

color phase and the color phase ratio (for a similar

technique, see Warner, 1975b).

Small populations of Thalassoma bifascialum

differ greatly from large populations in two ways:

(1) in the proportion of initial phase fish that are

males, and (2) in the color phase ratio (and hence

the sex ratio) (Warner, Robertson, and Leigh, 1975).

Only relatively large populations of the other

diandric species were sampled.

We also provide quantitative information on the

types of habitats in which we encountered each

species. The relative abundance of each species was

estimated by making counts in a series of 10 minute

swims in a series of habitats and at different depth

profiles, in a number of different sites. These habitats, which include the majority of the substrate

types we encountered, were (1) shallow (<5m depth)

Sargamim beds (large dense stands up to 50 cm

thick), (2) turtle grass beds (large, dense stands of

Thalassia) in water <5 m deep, and (3) hard reef

areas of coral or coralline rock, including sand

bottoms thickly dotted with coral growths. In this
NUMBER 254

latter habitat a series of sampling runs were made

on each of the following depth profiles: <3 m,

3-6 m, 6-9 m, 9-12 m, 12-15 m, 15-18 m.

Results

Bodianus rufus.—There are no indications that

this species exhibits sexual dichromatism, either

from the work of other researchers (e.g., Feddern,

1963; Randall, 1968; Bohlke and Chaplin, 1968) or

from our own observations. We found both sexes

in a single color phase (Figure 1) and never saw

males develop a distinctly different color pattern,

even when they became sexually active.

This species is almost certainly monandric, since

males were found only at the upper end of the size

range and all males examined histologically were

secondary (Figure 1). Two males with transitional

gonads were found, both of them quite small for

their sex (170 and 185 mm SL). Female sexual

maturity is attained at about 100 mm, SL. We

obtained no information on the sex ratio in this

species, although limited observations by S. Hoffman indicate that it is strongly biased towards

females (Table 1). The males had disproportionately small gonads relative to males of other species

(Table 2).

Bodianus rufus was relatively uncommon and

occurred at a variety of depths on hard reef substrates (Table 3). We found it associated with sites

of marked structural complexity, on the outer rims

of reefs. Adults usually occurred singly or occasionally in very transient aggregations of up to six

individuals of various sizes. We never saw them

forming schools or feeding in coordinated groups.

This suggested to us that B. rufus had a social

system similar to that of the labrid Labroides

dimidiatus, which forms permanent harem groups

composed of a single male and several smaller females (Robertson, 1972). Such has since been found

to be the case (S. Hoffman, pers. comra.).

The mating systems of these two species are also

essentially the same. In both, spawning occurs only

within the social group. We have observed pair

spawning in B. rufus in the very late afternoon.

Our data on breeding seasonality are too incomplete to show anything beyond the fact that breeding occurred in both wet and dry seasons (Table 4).

Apparently females do not continuously produce

eggs, since we often collected inactive, active, and

ripe females from the same location on the same

day.

Halichoeres bivittatus.—The different color pat40-

30-

20-

10

„ El n

BOOIANUS

in Hi

0

1

RUFUS

kiln

0 0 0

1 1 3

n

0

4

n

0

5

0

1

Initiol phase

n = l95

n<t*2A

o o \°<r

1 1 2°(T

80 90 100 110 120 130 140 150 160 170 180 190 200210 220230 240250

Standard length (10mm size classes)

FIGURE 1.—Pattern of sexuality in Bodianus rufus: size/frequency bar graph of

our sample, with indication of sexual ontogeny of a number of the males in

each size class (n = sample size in specified color phase; 1°,$ = primary males;

2° $ = secondary males; stippled bars = females; white bars = males; due to

subsampling of more numerous size groups and losses during processing, the

number of males histologically analyzed for sexual origin often falls short of

the total number of males in the sample; lengths were measured to the nearest

mm; placement in size classes follows the pattern of all fishes 10-19 mm SL

belonging in the 10 mm size class).
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

terns shown by individuals of various sizes have

been described by Roede (1972) (see also Randall,

1968; Bohlke and Chaplin, 1968; and Chaplin and

Scott, 1972). Halichoeres bivittatus is judged to be

sexually dichromatic since (1) the largest adults

have a color pattern very different from that of

smaller ones, and (2) individuals with this terminal

color pattern most strongly developed were invariably males. The situation, however, is far from

simple, as was also found by Reinboth (1975) and

Roede (1972). There is no distinct cutoff point

between the two phases (i.e., the division indicated

in Figure 2 is rather arbitrary, based on degrees

of brightness in colors of large specimens). Also, the

color pattern of the largest females contains all the

elements of the terminal phase (as was also found

by Roede, 1972). The dichromatism is therefore

only partial. With increasing size of the terminal

phase males, colors tend to become brighter, but

the colors of all such males fade when they are

sexually inactive. The distinctions between the two

phases then became much less obvious. We made

many of the decisions regarding color phase when

a specimen was dead, since coloration was typically

easier to distinguish at that time.

Our estimates of the color phase ratio and degree

of color phase overlap are limited by this lack of

discrete dichromatism. However, the color phase

ratio appears quite heavily biased towards the

initial phase (Table 1). Terminal phase males

tended to be much larger than initial phase fish.

Within each local population, there was little overlap in the size ranges of the two color phases: in

one sample of 32 initial phase and 11 terminal phase

fish there was only a 5 mm overlap in the standard

length ranges. Because the size of transformation

differs from one population to another, Figure 2

shows more overlap than actually exists on a single

reef.

Both primary and secondary males were found in

this species (Figure 2; see also Reinboth, 1975, and

Roede, 1972). Also, primary males were present in

relatively high and similar proportions in both

color phases (Figure 2; Table 5). The few secondary

males in the initial phase occurred only among the

largest size classes (Figure 2). Only one secondary

male with a transitional testis was collected (71 mm

SL). Since the smallest females we collected were

60-

50-

40-

N 30-

20

10-

Terminal

phase

n*47

f1]

5

0

1

1°

2«

1

|

10

0

HAUCHOERES BIVITTATUS

8

8

I

J

4

0

n

5

0

-

1

10

0

n

3

4

0

2

n

i

3

2

0

fl

1

6

0

1

n

0

3

r

2

n

i

2

8

"8

n n n

0 I 0

3 2 2

Initial phase

n = 247

-20

• 10

0 K) 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

Standard length (10 mm size classes)

FIGURE 2.—Pattern of sexuality in Halichoeres bivitattus (for explanation

of format, see Figure 1).
NUMBER 254

sexually active, we were unable to determine the

size at maturity.

While the testes of both primary and secondary

terminal phase males were somewhat heavier than

those of initial phase males, there were no significant differences in the weights relative to body

weights (Table 2). In terms of the entire population

sampled, however, there was considerable variation

in these relative weights, and a graph of the relationship between fish length and relative testis

weight (Figure 3) shows that the small males,

regardless of their origin or color phase, had relatively larger testes.

The sex ratio was quite equable (Table 1), principally due to the large complement of males in the

initial phase.

Although we found this species in a great variety

of habitats, it reached its greatest densities in the

dense stands of Sargassum that capped the tops of

many reefs. It was largely limited to these shallow

HALICHOERES BIVITTATUS

9-

8-

3 6-

2-

KEY

z>6

Initial phase

Terminal phase

I 2 3 4 5 6 7 8 9 10 II 12 13 14

Standard length (cm)

FIGURE 3.—Gonad weights (shown as percent of body weight)

for various sizes of male Halichoeres bivittatus.

habitats (<5 m), where it was the most abundant

labrid (Table 3).

We saw no indication of permanent territoriality

by individuals of any size or sex class. Outside

periods of sexual activity, fish of widely varying

sizes and from both color phases commonly formed

transient, loosely knit aggregations of up to forty

individuals. The overall impression was one of

independent movement of individuals at most times

of the day, with opportunistic scrambles for food.

The mating system of large populations of this

species resembles that of large Thalassoma bifasciatum populations (see Warner, Robertson, and

Leigh, 1975). Breeding was restricted to several

hours in the midafternoon and was concentrated

around the periphery of reefs in shallow water.

The greatest activity occurred in areas where the

species was abundant at other times. In these

spawning grounds, terminal phase males defended

temporary territories in which they pair spawned

with single females. Group spawning occured commonly in and around terminal phase fishes' territories. These groups consisted mainly of initial

phase fish, but occasionally a terminal phase individual would join as well. Initial phase males also

interfered in the pair-spawning activities of the

territorial males, behaving in similar fashion to

that described for T. bifasciatum by Warner, Robertson, and Leigh (1975). We never observed, however, the aggregates of hundreds or thousands of

initial phase fish that were common with T. bifasciatum; the initial phase aggregates in H. bivittatus

typically numbered about twenty fish.

Halichoeres bivittatus evidently spawned throughout the year (Table 4). Not all females, however,

were continuously active: we often obtained both

active and inactive females in the same sample.

Some sketchy evidence suggests that active and

inactive females tended to be in different parts of

the same reef. In collections made outside spawning periods, few of the females collected from the

center of reefs were ripe, while many of those

caught near the edges of reefs were. Possibly there

are cycles of movement of females from one area

to another corresponding to cycles of their gonadal

activity. It should also be noted that while collections from reef center and reef edge contained both

sexes, for practical reasons we were unable to determine sex ratios in the reef-center samples. Our

overall estimate of the sex ratio may then be biased.
8

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Halichoeres radiatus.—Since the largest adults

have a color pattern very different from that of

small ones (see Randall, 1968; Chaplin and Scott,

1972), this species is probably sexually dichromatic.

Whether such dichromatism might be partial or

full is not clear; we saw complete intergradation

between the two patterns. Because of their extreme

shyness, terminal phase fishes could not be collected

for sex determination. Whether such fish retained

these terminal colors permanently or were capable

of temporarily losing them is also not known.

Terminal phase fish were rarer and larger than

initial phase fish.

Reinboth (1975) found that this species was hermaphroditic. Although only secondary males were

present in the sample we obtained (Figure 4), our

sample sizes are too small to show whether the

species is monandric or diandric. The smallest

mature female we collected was 160 mm SL. Secondary males were present in the initial phase and

began appearing in the population at sizes smaller

than that of the smallest mature female (Figure

4). The smallest secondary male collected did not

have transitional gonads. The males collected all

had small testes, relative to their body weight

(Table 2). We were unable to determine the sexratio.

Halichoeres radiatus was largely restricted to

areas of coral cover, where it was found at all

depths sampled (Table 3).

Individuals were normally seen moving about

singly. However, on several occasions in midafternoon we observed an intensely colored terminal

phase fish moving actively about a loosely knit

group of about six initial phase fish. Beyond this

probable example of premating behavior, we have

no information on spawning or breeding seasonality in this rather secretive species.

Halichoeres garnoti.—Roede (1972) has described

in detail the range of color patterns shown by this

species (see also Randall, 1968; and Chaplin and

Scott, 1972). Although both an initial and a terminal phase exists, and all terminal phase fish we

collected were males (see Figure 3), sexual dichromatism is only partial. The distribution pattern

of coloration types is similar to that of H. bivittataus. An element of doubt remains as to whether

or not this species is really dichromatic. Our results and those of Reinboth (1973) tend to show

that it is, but Roede (1972) reported finding large

females showing the terminal color pattern. Both

large initial phase and terminal phase fish were

capable of completely losing the characteristic angled black bar on the body temporarily, which

complicated both our attempts to obtain field estimates of color phase ratios and to resolve the question of the degree of dichromatism. Death colors

were often used to assess the color phase of a specimen. The color phase ratio was moderately biased

toward the initial phase (Table 1), and there was

little if any overlap in the size ranges of the two

phases within a population: in each of 10 samples

(totalling 23 terminal and 86 initial phase fish),

there were no overlaps.

Halichoeres garnoti is evidently monandric. All

males we examined histologically were secondary,

ion

.. 1

-l>—1 1 1-

in

0

1

HALICHOERES

m Pil rM

RADIATUS

0 0

1 1

Initial phase

n = 27

nd" = 4

0 I'd1

1 2°d1

80 90 100 110 120 130 140 150 160 170 180 I9O20O2I0 220230240250 260

Standard length (10mm size classes)

FIGURE 4.—Pattern of sexuality in Halichoeres radiatus (for explanation of format,

see Figure 1).
NUMBER 254

and we found no males among the smaller size

classes (Figure 5). Both Reinboth's (1975) and

Roede's (1972) results agree with this. The few

initial phase males collected were all relatively

large (Figure 5). Most of them (5 of 6 examined)

had transitional gonads. The smallest females we

obtained were already sexually active.

Relative to body weight, the gonads of males

of both color phases were small when compared

to other species; those of terminal phase fish were

both absolutely and relatively larger than those

of initial males (Table 2). The sex ratio was moderately biased in favor of females (Table 1), mainly

because of the paucity of males in the initial phase.

This species occurred in reef areas containing

much sand dotted with scattered coral growths. As

Table 3 shows, it was restricted to areas containing

hard corals and occurred most commonly in the

deeper parts of such areas.

Terminal phase males did not appear to be

permanently territorial; however, the small aggregations that formed at baits typically contained

only one highly colored terminal phase fish, the

largest individual present. This suggests either

some exclusion of other large males from an area

by a resident terminal phase male, or some effect

of dominance relationships on the display of ter4 0 -

30-

20-

10-

HAUCH0ERE8 GARNOTI

IWIIMNH

phOM

n-32

1 ** 0

2"d* 2

.1

'•".-

'"•".'•

\

0

3

nfln

0 0 0

1 3 4

n

0

4

n m

0

5

Initial phase

H n

0 0

2 1

no*

1"

2°

= 10

<f

9

20

I

K)

60 70 80 90 100 110 120 130 140 150 160

Standard length (10mm size classes)

FIGURE 5.—Pattern of sexuality in Halichoeres garnoti (for

explanation of format, see Figure 1).

minal phase colors.

Pair spawnings between a large brightly colored

terminal phase fish and a smaller initial phase

individual were seen on several occasions in the

same habitat where the species was usually found.

Such sexually active males appeared to be scattered

about singly in this habitat rather than clumped

at any particular sites.

We collected ripe females in both wet and dry

seasons, and saw terminal males displaying sexually

throughout the year (Table 4). Beyond this, we

have no information on breeding seasonality. Females at all stages of oogenic activity were often

collected in the same sample.

Halichoeres maculipinna.—Detailed descriptions

of H. maculipinna's color patterns are given by

Roede (1972) and good color illustrations by Randall (1968) and Chaplin and Scott (1972). The

species shows full sexual dichromatism since all

terminal phase fish collected were males (Figure 6)

and the terminal pattern contains several elements

not present in the initial pattern. However, the

terminal phase males can temporarily lose the elements characteristic of their phase. This species

also possesses a juvenile color pattern, some elements of which are retained by small adults. Death

colors were often used in determining the color

phase of collected specimens.

The color phase ratio was strongly biased towards the initial phase (Table 1), but this can be

considered as only an approximation due to the

lack of a permanent terminal pattern. The few

data we have show a small degree of intrapopulational overlap in the size ranges of the two phases.

The phases overlapped in two of three collections

comprising 19 terminal phase and 59 initial phase

fish, but by less than 1 cm SL in each case.

Although Reinboth (1975) suggested, on the basis

of a rather small sample, that H. maculipinna was

monandric, our data show otherwise. Both primary

and secondary males were present in both color

phases (Figure 6). The proportion of primary

males in the two color phases differed in our samples with comparatively more in the terminal phase

(Table 5). Secondary males were found throughout

the initial phase size range, including some well

below the smallest sizes of terminal phase fish.

They also formed a large proportion (0.41) of the

initial phase male population (Figure 6). Of these

seven secondary initial phase males, the three which
10

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

4 0 -

30-

20-

10-

Terminal

phase

n=35

r

HALICHOERES f

If

,11

n

\°a 2

2°<J 1

:

 n hi

2 4 2

0 3 1

rfACUUPINNA

n

i

4

m

2

3

n

0

II

(1

4

5

I»<J

2°rf

n „

1 0

4 1

Initial phase

n* 112

n«J = l7

- 2 0

- 1 0

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Standard length (10mm size classes)

FIGURE 6.—Pattern of sexuality of Halichoeres maculipinna {for explanation

of format, see Figure 1).

we examined had transitional testes. The gonads

of initial phase primary males tended to make up

a higher proportion of body weight than those of

either primary or secondary terminal phase males

(Table 2). Although the three initial phase secondary males examined had small testes, the sample is too small to determine whether or not the

gonads of such males are consistently smaller than

those of primary males in the same color phase.

The sex ratio was not strongly biased towards

females (Table 1). The smallest females in our

sample were already sexually active.

This species was most abundant in shallow Sargassum beds on the tops of reefs, but was also

common on and adjacent to hard reef substrates.

In the Sargassum it was the second most abundant

labrid, reaching densities there higher than those

of any species other than H. bivittatus (Table 3).

We detected no indications of strong permanent

territoriality by members of either color phase.

Their movements overlapped each other, without

recognizable defense of specific areas. Feeding aggregations of up to a dozen or so individuals

readily formed at baits.

Sexually active, intensely colored terminal phase

males were regularly observed in midafternoon

along the shallow outer rims of reefs. There they

defended temporary reproductive territories within

which they spawned singly with females that approached them. Such territorial males were widely

scattered rather than being clustered in discrete

areas. Initial phase males participated as streakers

in six of 168 pair spawnings observed. In four

cases, initial phase males induced pair spawnings

with females that were responding to a courting

terminal phase male in the immediate vicinity.

We have observed group spawning involving small

aggregations of less than twenty initial phase individuals on three occasions, on two large reefs containing many H. maculipinna.

The species as a whole bred throughout the year

(Table 4), although not all mature females were

continuously active, since we often collected both

active and inactive specimens in the same sample.

Halichoeres pictus.—Good descriptions and figures of the color phase of this species are contained

in Randall (1968) and Bohlke and Chaplin (1968).

Our data show that it is sexually dichromatic. This

dichromatism is full, strongly expressed, and permanent. Fading of most of the diagnostic color
NUMBER 254 11

elements however, was observed in sexually inactive terminal phase males. The color phase ratio

was strongly biased towards the initial phase (Table

1). The degree of intrapopulation overlap in the

size ranges of the two phases, as shown by the

few data we have, was quite low. In two collections (10 terminal and 44 initial phase fish) there

was one overlap, of only 2 mm SL.

Both color phases of H. pictus contained primary

and secondary males (Figure 7). The terminal

phase also contained significantly more primary

males than did the initial phase (Table 5). One

secondary male (93 mm SL) with transitional gonads was collected; it did not have fully developed

terminal colors. Initial phase primary males had

relatively heavier testes than those of primary or

secondary terminal phase males (Table 2). The few

secondary initial phase males had relatively large

testes. The sex ratio was moderately biased towards

females (Table 1), mainly because of the paucity

of initial phase males. We were unable to determine size at maturity.

We observed H. pictus only on the outer faces

of reefs, typically at shallow depths on slopes that

faced deep open water. It was one of the least

common labrids, both overall and within its typi4 0 -

3 0-

20-

HALICHOERES PICTUS

Terminal

phase

n = 29

IO«. O

I O ^

2°o 1

2 4 2

0 1 1

-* f . • —.

n

4

4

1

fl

3

7

m

n

0

4

Initial phase

n = 116

nrf=l2

l-tf

20

I

10

cal habitat (Table 3). This species was usually

clumped in small aggregations of up to forty individuals of both color phases. There were no indications of permanent territoriality within such

groups and the fish fed quietly together in midwater.

We have little significant information on this

species' mating system. We noted a few pair spawnings involving an intensely colored terminal phase

male and a smaller female, and some aggressiveness

between such sexually active males.

Halichoeres pictus bred during both wet and

dry seasons (Table 4) and probably continuously

throughout the year. As with other labrids, not

all females were continuously producing eggs.

Halichoeres poeyi.—Although two color phases

are distinguishable in this species (see Randall,

1968), the patterns of these intergrade smoothly,

particularly with respect to body color elements.

Our delimitation of these phases was therefore

based largely on tail colors, with terminal phase

fish having three convergent pink tail lines as

figured in Chaplin and Scott (1972: pi. 16: fig. 2).

Terminal phase fish were all males (Figure 8), and

the larger they were, the more strongly developed

were their characteristic colors. Sexual dichromatism

in this species is thus full by definition, but rather

subtle. Death colors were often used when making

decisions about a specimen's color phase. The color

phase ratio was moderately biased towards the

20

30-

20-

10-

-iiTerminal

phase

n=26

HAUCHOERES POEY

•(f

2°J

_

1 1

5 5

2 8

n

0

1

]

h

i

7

1 1 n

0 0

5 7

irl n

0

3

n

2

1

\°<r

2°d

n_0

5

n

0

2

n

0

1

Initial phase

1

n

ncT

•143

- 3 6

40 50 60 70 80 90 100110 120130

Standard length (10mm size classes)

FIGURE 7.—Pattern of sexuality in Halichoeres pictus (for

explanation of format, see Figure 1).

30 40 SO 60 70 80 90 100 110 120 130 140 150

Standard length (10mm sin classes)

FIGURE 8.—Pattern of sexuality in Halichoeres poeyi (for

explanation of format, see Figure 1).
12

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

initial phase (Table 1). There was little within-site

overlap in the size ranges of the two color phases. In

a total of six collections (of 15 terminal phase and

82 initial phase fish), there were three overlaps, all

of less than 1 cm SL.

Primary and secondary males were present in

both color phases of H. poeyi (Figure 8) and primary males were about equally represented in both

(Table 5). Secondary males occurred in all size

classes of initial phase males, and included fish

much smaller than the smallest terminal phase

males. Males (mostly secondary) constituted quite a

large proportion (0.25) of the initial phase. A high

proportion (0.45) of the initial phase secondary

males had transitional gonads. These were concentrated in the larger size classes (70-100 mm SL).

Gonad weights in this species (Table 2) were too

variable to indicate any clear relationship between

them and color phase. We collected no immature

individuals.

As a result of the combination of a moderately

biased color phase ratio and an abundance of initial

phase males, the sex ratio was not strongly biased

towards females (Table 1).

H. poeyi was restricted chiefly to turtlegrass and

shallow sessile Sargassum beds; in the latter it was

one of the more abundant species (Table 3).

No members of either color phase showed any

signs of being permanently territorial. Individuals

overlapped broadly in their movement, and none

appeared to defend discrete areas. Small feeding

aggregations of individuals of both color phases

would rapidly form at baits.

Sexual activity occurred in midafternoon around

the edges of reefs in the species' normal habitat.

Terminal phase males became intensely colored,

defended territories, and pair spawned with females.

No spawning by initial phase males was noted, but

we spent very little time observing this species.

Our data show that breeding occurred in both

wet and dry seasons (Table 4). As usual, not all

females were continuously producing eggs. There

were more ripe fish taken from the edges of reefs

than from the centers of reefs, a situation similar

to that described for H. bivittatus.

Clepticus parrac.—Neither Randall (1968) nor

Bohlke and Chaplin (1968) adequately described

coloration in this species. We have found that it is

fully sexually dichromatic. The bodies of terminal

phase males are dark blue, an orange area covers

the caudal peduncle and extends down above the

anal fin and along the belly, and the tail is light

purple. Sexually active terminal phase males develop these and other color elements much more

strongly (Robertson and Hoffman, in press). Initial

phase fish have uniformly light blue bodies and

fins, with no orange markings.

The color phase ratio was relatively weakly biased

toward the initial phase (= females) (Table 1) and

from the few data we obtained there appeared to

be little overlap in the size ranges of the two color

phases within a population: of the two overlaps in

five collections (eight terminal and 44 initial phase

individuals) the largest was 1.2 cm SL. We observed

little indication of greater overlaps.

Clepticus parrae is evidently monandric. All

terminal phase males examined histologically were

secondary and no initial phase males were detected

(Figure 9). No males with transitional gonads were

collected. The sex ratio was moderately biased in

favor of females, due mainly to the absence of

males in the initial phase. We were unable to determine size at maturity, since all fishes we collected

were sexually active.

We invariably found Clepticus parrae moving in

open water well off the edges of reefs, particularly

where these faced deep channels or open water.

40-

30-

20-

10-

CLEPTICUS PARRAE

Terminal

phase

n=32

n n n n~

10

I'd* 0 0 O 0 0

2°<? 4 2 9 10 II

Initial phase

n=M9

R

90 100 110 120 130 140 150 160 170 180 190

Standard length (lOmm size classes)

FIGURE 9.—Pattern of sexuality in Clepticus parrae (for

explanation of format, see Figure 1).
NUMBER 254 13

Because of this tendency to move off into open

water, we have not included it in our relative

abundance estimates. In certain areas, however, it

was quite common.

We often observed it in large school? containing

hundreds, or even thousands, of fishes of both color

phases. There were no indications of any permanent

territoriality by any of these. They ranged over

large distances, feeding together.

The spawnings we observed in this species occurred at the edges of reefs. Periods of sexual activity lasted for several hours each day, from midafternoon onwards. Strongly colored terminal phase

males would pair spawn with smaller females.

Robertson and Hoffman (in press) describe pair

spawning in this species, which differs radically

from any other known labroid pattern. There were

no signs of any streaking by other males during pair

spawnings. We did observe however, that single

terminal phase males would approach courting

pairs and attempt to supplant the paired male.

These approaches led to vigorous male-male fights,

with the intruder usually being driven off. In two

cases, a male larger than the paired one succeeded

in displacing it and spawned with the female

involved.

Clepticus parrae spawned the year round (Table

4). As with other species, not all females were continuously active. With this species in particular

there were strong suggestions of cycles of reproductive activity at the population level. At one

regularly and frequently visited spawning site, we

observed activity on some days but none on others.

Thalassoma bifasciatum.—We have dealt with

this species elsewhere (Warner, Robertson, and

Leigh, 1975). Here we recapitulate and add relevant

material.

Thalassoma bifasciatum is fully sexually dichromatic, with the dichromatism being the strongest

and most permanent of any of the Caribbean

labrids. Terminal phase males have not evidenced

any capability of temporarily reverting to the initial

coloration.

The color phase ratio varies considerably from

population to population, being most strongly

biased towards the initial phase in large populations

(data from a large population are given in Table 1).

The degree of overlap in the size ranges of the two

phases within populations was quite small (Figure

10).

THALASSOMA BIFASCIATUM

30-

20-

10-

4 0 -

3 0 -

20-

20-

10-

P0PULATI0N I

Terminal

phase

n = 53

-20

-10

m n

Initial phase

n = 92

POPULATION II

Terminal

phase

n=l7

-20

-10

n

Initial phase

n = 123

n

POPULATION

Terminal

phase

n n _

Initial phase

n n n n _

n= 61

-20

10

30 40 50 60 70 80 90 100 110

Standard length (10 mm size classes)

FIGURE 10.—Size/frequency bar graphs for collections of

Thalassoma bifasciatum from three localities, showing color

phase overlap.
14 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

The species is diandric, with both male types

being present in both color phases (Figure 11; see

also Reinboth, 1973). However, primary males were

less common (in both color phases) in small populations than in large ones (Warner, Robertson, and

Leigh, 1975). Overall, they were equally abundant

in the two phases in each type of population (Table

5). The few secondary males present in the initial

phase were found in the largest size classes (Table

6). A substantial proportion of such males had

transitional testes. Initial phase males had gonads

relatively heavier than those of terminal phase

males (Table 2). Initial phase primary males had

the heaviest testes (in absolute terms) of all male

340

320

300

280

260

240

220

200

180

160

140

120-

100-

80-

60-

40-

20

THALASSOMA BIFASCIATUM

Terminal

phase

n=225

- n

I'd* n 0 0 II 15 9 2 0

7 6 35 70 39 22 4

Initial phase

n = 2148

nrf=755

0 0 2 3532 2 Z'i

-100

-80

-60 N

-40

-20

10 20 30 40 50 60 70 80 90 100 110

Standard length (10 mm size classes)

FICURE 11.—Pattern of sexuality in Thalassoma bifasciatum (for explanation

of format, see Figure 1).
NUMBER 254 15

types, although they were among the smallest in

body size.

The sex ratio varied considerably between populations and depended upon both variations in the

color phase ratios and the abundance of males in

the initial phase. Thus, although there were comparatively many more terminal phase males in

small populations than in large ones, the sex ratios

in small populations were more strongly biased

toward females (see Warner, Robertson, and Leigh,

1975).

Thalassoma bifasciatum was associated mainly

with coral reef areas, particularly around the

periphery of reefs. It also extended into adjacent

areas that were sparsely provided with solid shelter. Both in its main habitat and in general, it was

one of the more abundant species (Table 3).

This species often formed aggregations of hundreds or thousands of individuals of both color

phases. These actively fed on plankton at the edges

of reefs. Similar aggregations formed readily at

baits. Observations on tagged fishes of both color

phases showed that they had home ranges that

overlapped greatly and there was no well defined

permanent territoriality.

The mating system of large populations of this

species resembled that of lek-forming birds. In the

middle of each day temporary concentrations of

territorial terminal phase males formed at certain

sites where they pair spawned with females that

visited them. Group spawning was common, as was

streaking and sneaking by initial phase males (see

data in Warner, Robertson, and Leigh, 1975).

Breeding occurred throughout the year (Table 4),

although not all females were continuously active.

Discussion

PATTERNS OF POPULATION STRUCTURES AND THEIR

RELATIONSHIP TO LIFE HISTORIES.—We assume that

our samples reflect the life history patterns found

within each species. In deducing the life history patterns from sample structures we made two basic

assumptions: (1) The absence of a sex or coloration

type above a certain (submaximal) size indicates

that by the time individuals of that type have

reached that size, they all have moved into another

class (i.e., changed sex and/or coloration); and (2) all

individuals are capable of reaching the maximum

size.

It is possible, of course, that an individual following a certain pattern invariably dies at a size significantly less than the maximum for the species.

Then the absence of a type above a certain size

would result from those individuals dying rather

than changing into another type. For example, the

fact that terminal phase males are found in size

classes larger than the maximum for females might

be due to all the females having died before they

have reached a large size. Alternatively, all females

may have changed sex before they reach the maximum size. Histological examination helps to eliminate the possibility of differential mortality by indicating the previous history of the individual.

Transitionally colored individuals also aid in establishing the patterns of transformation. The consideration of a combination of sample structure,

histology, and transitional individuals can usually

show which pattern is present by a process of

elimination.

LABRID LIFE HISTORY PATTERNS.—Diandric Species: There appears to be one rather common pattern for the development of terminal phase males

from individuals that start life as females: sex

change is followed rapidly by color change. In each

species for which we had reasonable numbers of

initial phase secondary males (Halichoeres bivittatus, H. maculipinna, H. poeyi, and Thalassoma

bifasciatum), a large proportion of those males had

transitional gonads. We feel that this indicates rapid

transition of secondary males into the terminal

phase, with most individuals spending little or no

time in the initial phase once their sex change has

been initiated. The restriction of secondary males

to the upper end of the initial phase's size range in

H. bivittatus and T. bifasciatum supports this idea

(Figures 2 and 11; Table 6). Also, Reinboth (1973)

pointed out that in his sample of T. bifasciatum, no

transitionally colored secondary male had transitional gonads, indicating that completion of sex

change had occurred before that of color change.

On the other hand, Roede (1972) found the great

majority of specimens having "intersexual" gonads

in this species were transitionally colored or fully

terminally colored. Her definition of "intersexual,"

however, is much broader than our "transitional."

In our samples, only Halichoeres pictus appeared
16

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

to show any synchrony in change of sex and color.

Whether this might also occur in the other Halichoeres species is not clear, because they lack radical

dichromatism.

Additionally, in diandric species, primary and

secondary males appear to change coloration within

the same size range. This is indicated by the smallness of overlaps in size between the initial and

terminal color phases.

Monandric Species: Bodianus rufus has the simplest pattern seen in the Caribbean labroids. It is

monochromatic, and sex change occurs over a small

size range. In the dichromatic Clepticus parrae, the

two transitionally colored males we collected had

fully functional gonads, indicating that sex change

probably precedes color change. If Halichoeres

garnoti is truly sexually dichromatic (see above), its

sexual pattern is similar to that of C. parrae: sex

change followed by rapid color change.

In none of these three monandric species is there

any tendency for early sex changes (i.e., prematurational or early postmaturational), which are common in the monandric parrotfishes (see Robertson and Warner, 1978). Our meager sample of

Halichoeres radiatus indicates, however, that prematurational sex change does occur in this species.

Its significance is unknown.

SIGNIFICANCE OF TESTIS SIZE IN RELATION TO REPRODUCTIVE STRATEGIES.—Robertson and Choat

(1974) and Choat and Robertson (1975) showed

that in some of the dichromatic labroids, initial

phase males had much heavier testes relative to

body weight than did terminal phase males. They

related this to basic differences in the spawning

strategies of the two male types. Since initial phase

males usually spawn in groups, a selective premium

would be placed on possessing a large testis. An

individual releasing vast amounts of sperm in each

group spawning could increase the proportion of the

eggs that he fertilized relative to less productive

individuals. Terminal phase males normally spawn

singly with a female. Since sperm competition in

this case does not come into play, there is no selection for the development of a large gonad.

Data presented by Warner, Robertson, and Leigh

(1975) for Thalassoma bifasciatum show how strong

the dichotomy can be between the spawning patterns of the two male phases. Although there was

complete intergradation between the extremes of

pair and group spawning, 98.3% of the spawning

acts of initial phase males observed were group

spawning, but only 5.4% of terminal phase males'

spawnings involved more than one male. In this

species we have shown that initial phase males have

very much heavier testes, both absolutely and relatively, than do terminal phase males (Table 2;

Roede, 1972, especially fig. 2\b). This pattern also

holds true for some of the other dichromatic labrids

that we have examined (Halichoeres maculipinna

and H. pictus). With the weakly dichromatic H.

bivittatus, the differences in relative gonad weight

are between large males and small males rather than

strictly between color phases (Figure 3; also see

Roede, 1972).

The gonad weights of H. maculipinna also correlate with the differences in the observed spawning

patterns of the two color phases: terminal phase

males engage in pair spawning, while initial phase

males interfere in pair spawnings and participate in

group spawning. In this species, it seems unlikely

that group spawning is the predominant spawning

mode of initial phase males. Initial phase fertilization success in interference spawnings would also

be increased by the greater sperm production of

relatively large testes. We do not know the level of

zygote production by small males compared to that

of females of equivalent size. If it is much less,

initial phase males should be selected against

(Warner, Robertson, and Leigh, 1975); however, if

those males tended to participate as satellites in

pair spawnings involving large females, and fertilized a high proportion of the eggs in such cases,

then a relatively small number of spawnings by

them could lead to a zygote output equivalent to

that of small females. Halichoeres poeyi and H.

pictus may also show a similar relationship between

gonad size and spawning pattern.

Robertson and Choat (1974) also extended this

hypothesis to cover the situation in the monocromatic labrid Labroides dimidiatus. The small testis

weight of the males of that species correlates well

with the absence of spawning patterns other than

pair spawning. Neither the monochromatic Bodianus

rufus nor the dichromatic Clepticus parrae showed

any indications of multimale spawnings. The males

of both of these species have small testes, whose

relative weights are similar to those of the pair

spawning males of other labrids (Table 2).

Two further comparisons are instructive.

1. The testes of initial phase T. bifasciatum males
NUMBER 254 17

are heavier, both absolutely and relatively, than

those of the other diandric species (see Table 2).

The largest spawning aggregations of initial phase

males seen were those of T. bifascitum, in which

hundreds or thousands of fish were commonly present. For instance, on one well studied reef, an

estimated 15,700 initial phase fish visited the spawning area. The bulk of those were males (65% of a

sample of 100; Roede, 1972, obtained 85% males in a

similar collection). Actual spawning groups were

also large as well. Half of them contained an estimated 6-10 initial phase fish and another third an

estimated 11-15 such individuals. This follows our

expectations that the largest initial phase male testes

should be found in species in which group spawning is most strongly developed.

2. In T. bifasciatum, the pattern of large initial

phase male testes and small terminal phase male

testes holds true for both primary and secondary

males. One would expect this if both male types

evidenced common spawning strategies relevant to

a particular color phase. This suggests that selection can alter the size of the male gonad, and its

level of sperm production, regardless of its ontogeny.

The small sizes of secondary terminal phase males'

gonads are thus not necessarily the result of some

intrinsic limitation.

Warner and Downs (1977) examined patterns of

growth and longevity in primary males and hermaphrodites of the scarid Scarus croicensis and came

to the conclusion that primary and secondary males

in this species follow different life history strategies:

primary males appear to spend a relatively short

time in the initial phase by growing rapidly and

changing to the terminal phase sooner than the

hermaphrodites. They also die much sooner than

the hermaphrodites. Perhaps a similar situation

exists in H. maculipinna: initial phase male sexual

activity seems quite limited and there are relatively

high proportions of primary males in the terminal

phase (similarly in H. pictus, see Table 5). This

could be the result of relatively rapid growth by

primary males. In T. bifasciatum and H. bivittatus,

the proportions of primary males are the same in

both color phases. This may indicate a lack, of

accelerated growth by such males when they have a

high degree of spawning success (see data on T.

bifasciatum in Warner, Robertson, and Leigh,

1975); however, we do not exclude the possibility

that complex interactions between differential

growth and mortality rates could produce similar

proportions. In one population of T. bifasciatum

that we studied, the proportion of primary males

declined with increasing size in the initial phase,

suggesting growth or mortality differences. Sex specific movement and spatial distributions could also

lead to bias in the initial phase samples.

MATING SYSTEMS AND THE REPRODUCTIVE SUCCESS

OF INITIAL PHASE MALES.—In discussing the evolution of protogyny by natural selection (Warner,

Robertson, and Leigh, 1975), we concluded that the

presence or absence of dual mating strategies was

related to the strength of sexual selection, i.e., to the

difference in fertility between females and their

selected males. In T. bifasciatum, dual male strategies are represented by the spawning behaviors of

terminal and initial phase males. Intense sexual

selection, when coupled with sex change, leads to

high numbers of females relative to terminal phase

males in large populations. Management of so

many females by the dominant males is difficult, a

situation that allows initial phase males to be successful in group and interference spawning. In

small populations, sex ratios are more equable and

terminal phase males should be better able to control the entire spawning area. This would create

much less favorable conditions for initial phase

males and thus for primary males. We believe it

is for this reason that primary males are common in

large populations and rare in small ones (Warner,

Robertson, and Leigh, 1975).

The coexistence of nonhermaphrodites (primary

males) and sex changers in the same species was

explained as a form of frequency dependent selection. When initial phase males are rare, they would

be favored relative to heramphrodites, but would

be at a disadvantage when they are so common that

their average fertility was reduced below that of

females. A balance would be struck if the fertility

of initial phase males was equal to that of similar

sized females, which wo showed could occur in

large populations. Robertson and Choat (1974) and

Choat and Robertson (1975) suggested how this

argument might apply to interspecific comparisons.

They considered two radically different types of

species: those that live in permanent, territorial,

haremic groups, and those in which there is only

periodic territoriality by large males during periods

of reproduction. In the former type, a male mates

regularly, and almost exclusively, with the females
18

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

of his group, whom he probably knows individually;

while in the latter each temporarily territorial male

competes freely for any female during the spawning

period. A lack of free competition for mates in the

harem type enables territorial males to virtually

eliminate the possibility of breeding by small males.

They can be recognized and prevented from spawning, and excluded from the social group. Because

of low spawning success relative to hermaphrodites

during the early part of their lives, primary males

should not be able to maintain themselves in the

population of such a species (see also Warner 1975a).

This fits with the observation that haremic species

are monandric and have no small males.

In species in which males held only temporary

spawning territories the anonymity of the initial

phase males should facilitate their interference with

the spawning activities of territorial males. The

ability of terminal phase males to exclude them outside spawning periods would also be negligible.

In this type of species, small males could attain a

much higher level of success than they could in

species of the haremic type. When these small males

grow large, they can then assume the dominant male

behavior and coloration.

How does our data on the Caribbean labrids

relate to these hypotheses? Essentially, each species

can act as a test of the ideas, indicating where

modifications or expansions might be needed.

First, the relationship between social and mating

system types and the presence or absence of primary

males holds fairly well: Bod in tins rufus, which has

an haremic system, is monandric, with no evidence

of any small males. Of the remaining species for

which we have fairly comprehensive information,

most have nonharemic social systems, primary males

are present, and in many instances there is evidence

of initial phase male spawning activity.

Halichoeres garnoti and Clepticus parrae are the

only anomalous cases. We need more information

to resolve the situation in H. garnoti. It is the only

established monandric Halichoeres species, and it

contains no small secondary males such as exist in

nonharemic, monandric parrotfishes (Robertson and

Warner, 1978). These facts suggest that H. garnoti

may have a social and mating system of the haremic

type. A thorough study of the reproductive behavior

of this exceptional Halichoeres is needed.

Clepticus parrae is atypical for the Caribbean

labrids in several important ways. (1) It is the only

truly schooling, open water species and is the least

reliant on coral for shelter; accordingly, its morphology differs greatly from that of the other species

(see Davis and Birdsong, 1973). (2) It is both dichromatic and monandric, with no indications of any

existence of small initial phase males. (3) The combination of this pattern of color and sex change

with the nonharemic social and mating system of

this species appears to contradict the ideas of initial

phase male (and thus primary male) spawning success that we have presented. There are data dealing

with the finer details of the mating system, however, that may resolve this apparent conflict.

Spawning in C. parrae is unlike that in the other

species that we have observed. Terminal phase

C. parrae do not wait in small defended areas for

females to visit them but roam actively about in

overlapping manner over large distances. Robertson and Hoffman (in press) have described the

mating pattern in detail, contrasted it to that of

T. bifasciatum and discussed the adaptive significance of the differences. In C. parrae, females seem

to require long term tactile stimulation from a

persistent male to induce spawning, and the spawning sequence requires a high degree of coordination

and continuing physical contact between the pair.

Spawning thus requires considerable time and effort

by the male to induce participation by the female.

In T. bifasciatum, the terminal phase male puts

much less effort into each spawning. Courtships are

often very abbreviated, and reliance is placed on

visual displays rather than on tactile stimulation,

which is usually not needed. In contrast to the

situation in C. parrae, the spawning rush can be

much more easily triggered in females of T. bifasciatum; thus, the courtship and spawning sequence

is much more open to manipulation by initial phase

males. Because the females of C. parrae appear to

respond only to concerted and persistent tactile

stimulation of single males, interference spawning

(group spawning and sneaking) that rely on manipulation of the female's ready susceptibility to casual

tactile stimulation are probably not viable propositions in that species. Streaking, the only spawning

pattern of an initial phase male that does not involve tactile stimulation by him, could be a significant means of fertilization by an initial phase male

in C. parrae. In T. bifasciatum, however, streaking

contributes very little to initial phase males' spawning success: only 4.4% of pair spawnings were
NUMBER 254 19

streaked (n = 40 spawning periods) and only one

of 364 spawning acts by 15 initial phase males was

a streaking. We see no reason why C. parrae males

should be less effective at aggressively inhibiting

streaking than terminal phase T. bifasciatum.

In addition, C. parrae has the most equable color

phase ratio (= sex ratio) of any of the labrids considered here. This, combined with the long time

span involved in each spawning, means that each

terminal phase male probably has relatively few

successful spawnings per day. A loss of a single

spawning would then represent a major diminution

in a male's daily reproductive output and vigorous

defense of each female is to be expected. Thus the

conditions necessary for initial phase males to

achieve spawning success are certainly not present

in C. parrae.

We have reasoned that dominant males that succeed in minimizing the participation of other males

in spawning activities maximize their own spawning

success. Let us now examine in greater detail how,

in species such as T. bifasciatum, initial phase

males attempt to frustrate such activity and what

factors lead to their success or failure in doing so.

In species like T. bifasciatum the anonymity of

the initial phase male reduces the ability of terminal

phase males to discriminate against them. Initial

phase males in T. bifasciatum gain their spawnings

in a variety of ways and anonymity probably plays a

varying role in this, depending on their relative

abundance in the population. When initial phase

males are rare, their resemblance to females (suggested as being mimetic by Choat and Robertson,

1975) increases their chances of penetrating a terminal phase male's territory and sneaking or streaking his spawnings.

Labroids may be able to detect sex other than by

visual means. Randall and Randall (1963) suggested

that males of one of the scarids might be detecting

the sex of females chemically. Our observations of

T. bifasciatum and other labroids strongly suggest

that terminal phase males can distinguish between

females and initial phase males by following initial

phase fish and closely inspecting their vents. We

have repeatedly seen such behavior lead to a terminal phase male aggressively chasing a known initial phase male. Terminal phase males do not always

succeed in such a detection, however. Rarely, initial

phase males carry the mimicry a step further: we

have observed known initial phase males going

through the basic female motions of spawning with

a terminal phase male. Once this led to the initial

phase male sneaking a spawning with a waiting

female immediately afterwards.

With increasing abundance, the chances of all

initial phase males successfully employing the

"mimicry" strategy would decline. An alternative

mode of achieving success is to overwhelm the territorial male by numbers. A large territorial male is

able to break up groups of up to about twelve

initial phase males, and prevent them from group

spawning in his territory. Larger groups can enter

such a male's territory quite successfully and the

frequency of group spawnings increases with the

number of initial phase males present in the spawning area. In the presence of masses of about 50

initial phase males, large territorial terminal phase

males become hyperaggressive and chase out all

initial phase fish, including females. This, of course,

works in the initial phase males' favor, since females then become more available to them. Groups

of initial phase males also intercept females on their

way to a territorial terminal phase male and can

induce group spawning by tactile stimulation.

Group spawning, however, has some definite disadvantages to the participant male. An initial phase

male cannot always predict whether it will be adequately rewarded for joining a particular aggregation. There could be too few males to overwhelm

the territory owner or too many initial phase males

relative to the number of females. Because in the

initial phase both sexes are colored alike, initial

phase males have the additional problem of distinguishing females, and they often make mistakes.

About 50% of group spawnings yield no observable

eggs and appear to lack a female participant. This

leads to a considerable wastage of the groupspawning male's gametes. Finally, predatory fishes

often attack these male aggregations and eat individuals whose attention is concentrated on spawning.

As Warner, Robertson, and Leigh (1975) have

shown, initial phase male mating strategies work

well in situations where there are many females per

terminal phase male. The strategy of overwhelming

these males is most liable to pay off in these situations, and proportionately larger numbers of initial

phase males can attain spawning success. On larger

reefs, there are fewer terminal phase males per

female in T. bifasciatum: we previously attributed
20

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

this solely to the fact that a higher potential fertility of large males leads to more intense sexual

selection and hence to a later age of sex change

(Warner, Robertson, and Leigh, 1975). Topography,

however, plays a part in this phenomenon as well:

spawning sites (down-current corners) are limited on

any reef, and their number does not increase directly

with the size of the reef. If the number of successful

terminal phase males is limited by available spawning sites, we might expect there to be fewer terminal

phase males per female in large populations on big

reefs.

Another factor also acts on large reefs. Initial

phase male spawning success is achieved at the

expense of terminal phase male success. In situations in which initial phase male success is high, the

potential number of successful terminal phase males

may be reduced. The result is that fewer initial

phase fish change to the terminal phase, there being

no reproductive advantage in doing so.

For whatever reason, in large T. bifasciatum

populations, the color phase ratios are very skewed

(Table 1). In these populations, initial phase males

reach high proportions (Table 5) and apparently

achieve the same zygote production as females

(Warner, Robertson, and Leigh, 1975). Primary

males may be avoiding small reefs by emigration

while very small or by non-random settlement.

Fringing, barrier reefs tend to be large and they

may also be the first encountered by drifting

juveniles preparing for settlement. If primary males

tend to settle out on the first reef they encounter,

while hermaphrodites wait a longer period, there

might tend to be more initial phase males on large

fringing reefs.

We think that terminal phase males can effectively reduce initial phase male spawning activity

on small reefs in a manner analogous to male activity in harem forming species. In small populations,

an initial phase male would have less ability to

remain anonymous. A terminal phase male could

also directly benefit by detecting and excluding

specific initial phase males. This is much less

effective on a large reef. Also, because the overall

spawning activity of terminal phase males is lower

on small reefs due to the presence of fewer females,

more time may be available to that male for defense

and detection of small males. The only initial phase

male spawning strategy that could seem to work in

such situations involves "mimicry." With few females present the swamping technique would provide too little return for effort.

Since population size appears to have such a

strong effect within this one species, it might logically be expected to have similar effects in other

species that have similar social and mating systems.

In Table 7, we summarize the basic abundance and

sexual data for the five diandric labrids that we

examined. Generally, those species which have large

dense populations (measured by relative abundance

ranks) also have the strongest representation of

initial phase males. Halichoeres pictus, which occurs in small isolated clumps, has the fewest such

males. This relationship is in general accordance

with what we have found within T. bifasciatum.

The situation, however, is potentially far more

complicated than would be indicated from simple

comparisons of initial phase male abundances and

population sizes. The social system is probably the

most critical factor in determining initial phase

male success. We have shown this in the parrotfishes, where we had adequate numbers of haremic

and nonharemic species for comparison (Robertson

and Warner, 1978). Haremic species tended to have

lower proportions of initial phase males.

There are other strategies available to small

males, some of which we have already mentioned:

avoidance of populations in which reproductive

success is liable to be low, and rapid growth to

bypass an unfavorable phase. Choat and Robertson

(1975) also raise the possibility of differences in

age or size at maturity. Each strategy carries with

it a certain risk of death, and differential mortality is an important and often overlooked factor

in comparisons of reproductive success.

We have presented an overview of the patterns

of sexuality in the Caribbean wrasses. More patterns and further discussions can be found in the

companion paper on parrotfishes (Robertson and

Warner, 1978). Both of these studies provide a general impression of the factors working to shape the

life history patterns of tropical reef fishes. There

is still a critical need for detailed studies of single

species in a series of habitats. Only in this way can

we unravel the proximate factors affecting fitness.
Appendix 1

Definition of Terms

(Used herein and in Robertson and Warner, 1978)

COLORATION

juvenile phase. Having a color pattern characteristic of immature individuals,

initial phase. Having a color pattern characteristic of small adult individuals.

terminal phase. Having a color pattern characteristic of the largest males.

sexual monochromatism. Females develop the same color pattern as males.

sexual dichromatism. At least some males (terminal phase) have color patterns different from

females (initial phase).

full. Some coloration elements are present only in the terminal pattern.

partial. Initial and terminal patterns differ only in intensity of some color elements.

temporary. Males can revert to initial pattern.

permanent. Males cannot revert to initial pattern.

SEXUALITY

gonochorist. An individual that does not have the genetic capacity to change sex.

protogynous hermaphrodite. An individual that can change sex from female to male.

primary female. A gonochoristic female.

primary male (1° $ ). A gonochoristic male.

secondary male (2° $ )• A male resulting from the sex change of a female protogynous hermaphrodite.

prcmaturational. Sex change occurs before the female ever functions as an adult.

postmaturational. Sex change occurs after a functional female stage.

diandry. both primary and secondary males present in the same population,

monandry. All males present in a population are secondary.

MATING PATTERNS

leks. Males are territorial during spawning periods only. At such times they tend to aggregate

at traditional sites and vie for mating with the females who come to the sites to spawn.

harems. Males are permanently territorial and include within the territory a group of females

with whom they mate nearly exclusively.

pair spawning. A single male mating with a single female.

group spawning. A group of males mating with a single female.

sneaking. An initial phase male surreptitiously inducing a female to pair spawn within the territory of a terminal phase male.

streaking. Rushing in to join a male and a female at the climax of pair spawning.

21
Appendix 2

Terminology Applied to Labroid Color Phases

Authority

Randall, 1963

Randall, 1968

Rosenblatt and Hobson, 1969

Bohlke and Chaplin, 1968

Roede, 1972

Reinboth, 1973

Ogden and Buckman, 1973

Moyer and Shephard, 1974

Robertson and Choat, 1974

Roede, 1975

Reinboth, 1975

Barlow, 1975

Choat and Robertson, 1975

Warner, Robertson, and Leigh, 1975

Warner, 1975b

Warner and Downs, 1977

Juveniles

_

_

juvenile

-

juvenile

-

-

-

juvenile

juvenile

-

tiro

juvenile

-

-

Smaller adults

drab

drab

"female"

-

first adult

plain

striped

drab

drab

first adult

initial

mid

drab

initial

uniform

initial

Larger adults

terminal

terminal

definitive or terminal

super male

terminal

bright

terminal

bright

gaudy

terminal

terminal

term

gaudy

terminal

bicolored

terminal

22
Appendix 3

Tables

TABLE 1.—Color phase ratios and estimated adult sex ratios of eight species

of Caribbean wrasses (color phase data tallied in series of counts performed

during 10 minute swims in suitable habitats; overall sex ratios calculated

from the color phase ratio and the initial phase sex ratio, the latter data

from our collections)

Species

Bodianus rufus ..

Halichoeres bivittatus .

H macuHpinna

H. pictus

H. poeyi

Cleoticus parrae ...

Thalassoma bifasciatum ..

Number

of counts

13

27

18

11

12

12

l

b

Total number

of Individuals

from al1 counts

1299

998

747

333

486

770

5157

Color phase ratio

Terminal phaserlnitial phase

:6.8

:4.4

:6.5

:6.1

:4.9

:3.2

: 135

Sex ratio

t-.t

•8.5a

:1.2

•2.9

•2 5

•3 1

:1.4

:3.2

:1.2

aS. Hoffman, unpublished data.

bCount lasted approximately 20 minutes.

TABLE 2.—Testes weights of nine species of Caribbean wrasses, individuals

classified according to coloration and sexual ontogeny (the mean and its 95%

confidence interval shown for both absolute testes weights and testes weights

relative to body weight; this relative weight may be read as percent of body

weight; all secondary males used in this tabulation showed posttransitional

gonads)

Species

Bodianus rufus

Halichoeres bivittatus.

H garnoti

"- ***** *

Color phase

initial

initial

terminal

initial

initial

terminal

initial

terminal

initial

terminal

terminal

terminal

terminal

0

27

11

0

0

0

9

7

8

10

2

0

36

Gonad

(

0.04

0.10

0.03

0.04

0.P2

0.0?

0.04

0.21

0.05

Primary

weight

• 0.01

• 0.04

+ 0.01

• 0.03

* 0.01

• 0.01

+ 0.02

males

GW/BW x 100

(percent)

1.69 • 0.54

1.21 * 0.82

0.66 * 0.34

0.25 • 0.21

0.54 • 0.27

0.16 • 0.06

0.64

0.26 • 0.11

»

16

2

23

6

4

26

3

27

2

14

20

29

170

Seconda

Gonad weight

(9)

0.18 •

0.05

0.11 •

0.17 •

0.03 •

0.08 •

0.01

0.04 •

0.02

0.02 •

0.06 •

0.16 •

0.03 •

0.08

0.04

0.20

0.02

0.02

0.01

0.01

0.02

1.05

0.01

ry males

GH/BM x 100

(percent)

0.09 • 0.06

0.35

0.59 • 0.43

0.13 • 0.06

0.08 • 0.06

0.15 • 0.03

0.16

0.16 • 0.03

0.30

0.13 • 0.05

0.23 • 0.08

0.12 • 0.03

0.22 «0.0 3

23
24

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

TABLE 3.—Relative abundance of seven species of Caribbean wrasses

measured by habitat (numbers represent fish seen per 10 minutes by observer

swimming along a horizontal transect; these transects were run at the surface

for the first two habitats and along a series of depth profiles for the hard

reef)

Species

Haiichocres bivitutus

H. maculipinna

Thalassoaa bifasdatum

H. poeyi

H. qarnoti

Bodianus rufus

H. radiatus

Total sampling minutes

Sessile

Saraassum

137.6

84.4

31.2

—

5

50

Turtle

grass

139.5

2.1

1.4

....

"

26

260

i 3

10.7

0.9

31.5

1.5

4.2

1.3

0.7

32

380

3-6

3.9

0.6

7.3

0.5

«.2

2.2

0.6

29

410

Hard reef depth profile

6-9

6.1

0.1

3.9

0.9

4.0

1.3

0.4

16

205

9-12

0.5

0.1

2.1

0.7

9.9

2.7

0.4

8

95

12-15

0.1

0.4

0.4

9.9

2.7

4

65

(•)

15-18

0.5

2.8

11.4

3.2

0.6

2

85

TABLE 4.—Breeding seasonality in eight species of Caribbean

wrasses (+ = male sexual displays observed; + + «= spawning and male sexual displays observed, or ripe females collected; nd - no data available)

Species

Bod1 anus rufus

Halichoeres bivittatus.

H. garnoti

H. maculipinna

H. poeyi

Thalassoma bifasdatua.

Jan

++

++

nd

•+

Dry season

Feb

nd

+4

+

nd

++

Mar Apr

++ ++

•+ +•

•+ •+

+• +t

May Jun

++ ++

++ ++

•+ •

•+ •+

++ ++

Jul

nd

nd

Wet season

Aug

nd

++

nd

Sep

nd

• •

nd

Oct

nd

•

nd

Nov

nd

Dec

n<1

TABLE 5.—Distribution of primary males in the two color phases of five

diandric Caribbean wrasses (tests for differences in proportions of primary

males between initial and terminal coloration by means of the normal

statistic z - X, - X2/Vp(l-"p") (1/Nj + 1/N2), where X is the observed

proportion, N is the sample size, and p = (N ^ + N2X2)/(N1 + N2); see

Dixon and Massey, 1969:249)

Species

Ha11choeres bivitUtus...

H. maculipinna

H. pictus

H- ISfJl

ThalassoM bifasctatum

Large populations

Small populations

N

247

11?

116

143

690

167

Initial phase

Primary male

proportion

0.32

0.09

0.08

0.09

0.22

0.02

N

37

34

25

2fl

124

69

Terminal phase

Primary male

proportion

0.32

0.24

0.36

0.07

0.21

0.04

Test for differences

1n proportions

n.s.

p '0.05

p <0.001

n.s.

n.s.
NUMBER 254 25

TABLE 6.—Sexual ontogeny of initial phase males of Thalassoma bifasciatum collected from one population (proportion

of total of collected individuals in parentheses)

(inn SL)

40-49. .

50-59

60-69

70-79

80-89

14

15

17

15

4

65

14

15

15

13

2

17 (0.91)

secondary males

1

1

0

M0.03)

secondary males

1

1

2

4~(0.06)

TABLE 7.—Rank order of abundance within common habitat

and male proportion of initial color phase for five species of

diandric Caribbean wrasses

Habitat/Species

Sargassum, turtle grass substrates

Halichoeres bivittatus

H. maculipinna

H. poeyi

Hard reef substrates

Thalassoma bifasciatum

H. bivittatus

H. poeyi

H. maculipinna

H. pictus

Rank order of

abundance

1

2

3

1

2

3

4

5

Hale proportion of

initial color phase

.33

.15

.11

.22

.33

.11

.15

.10
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