DOI: 10.5061/dryad.pc866t21v
title: Data from: Functions of bidirectional sex change and simultaneously hermaphroditic phase gonads in the monogamous goby Lubricogobius exiguus

description: Hermaphroditism has been widely confirmed in fish and includes four
 recognized types: protogyny, protandry, bidirectional sex change, and
 simultaneous hermaphroditism. Among these, bidirectional sex change and
 simultaneous hermaphroditism are considered the most flexible sexual
 patterns, due to their frequent switching of functional sexes. They are
 predicted to evolve under conditions of limited mating opportunities, such
 as low population density and mobility, and are thought to share common
 evolutionary factors. The goby Lubricogobius exiguus exhibits
 bidirectional sex change, with simultaneously hermaphroditic (SH) phase
 gonads, containing both developed testicular and ovarian tissues,
 particularly in females and solitary individuals. In this study, we
 conducted field observations to examine the mating system in L. exiguus
 and investigate the significance of its plastic sexual patterns. The
 results revealed that the goby randomly formed mating pairs, regardless of
 body size. Although a few pairs maintained long-term mating relationships
 over 70 days, approximately half of the pairs dissolved within 11 days.
 Under frequent partner changes in the non-size-assortative monogamy, the
 goby individuals rapidly established new mating pairs through
 bidirectional sex change using SH phase gonads. This sexual plasticity
 enabled L. exiguus to initiate reproduction quickly regardless of the sex
 of the partner, supporting the evolutionary predictions underlying
 bidirectional sex change and simultaneous hermaphroditism. In addition to
 the characteristics of the mating system, ecological traits such as being
 a microhabitat specialist on sandy-bottom substrates with a short lifespan
 may have influenced the evolution of the sexual pattern in L. exiguus.
description: # Functions of bidirectional sex change and simultaneously hermaphroditic
 phase gonads in the monogamous goby *Lubricogobius exiguus* Dataset DOI:
 [10.5061/dryad.pc866t21v](10.5061/dryad.pc866t21v) ## Description of the
 data and file structure ### FILE Data breeding pair.csv  OVERALL
 DESCRIPTION: This file contains the data of breeding pairs in
 Lubricogobius exiguus. COLUMN EXPLANATION * Pair ID: "Identification
 number of the breeding pair" * Number of spawning: "Number of
 spawning observed in this study" * Pair period: "Pairing period
 in each pair (day)" * Male ID: "Identification number of male
 individual" * Female ID: "Identification number of female
 individual" * Male TL: "Total length of male individual
 (mm)" * Female TL: "Total length of female individual (mm)"
 * Size difference: "Absolute difference in total length between males
 and females in each pairs (mm)" * Observation type: "Types of
 observed cases for each pair. F represents the entire observed pairing
 period, while P represents only a part of the observed pairing
 period." * Cluster: "This variable represents the cluster
 assignment resulting from a cluster analysis based on two behavioral
 metrics: Pairing period and Number of spawning." NOTE: "NA"
 (non-applicable) is included in various columns to reflect instances in
 which we were unable to record the respective information for that
 variable. ### FILE Data sapwning.csv OVERALL DESCRIPTION: This file
 contains the results of observations on the spawning behavior of
 Lubricogobius exiguus. COLUMN EXPLANATION * Pair ID: "Identification
 number of the breeding pair" * Male ID: "Identification number
 of male individual" * Female ID: "Identification number of
 female individual" * Nest ID: "Identification number of the
 nest" * Spawning date: "Date of spawning or first egg
 confirmation (YYYY/MM/DD)" * Hatching date: "Date of egg
 hatching or disappearance (YYYY/MM/DD)" * Start time: "Start
 time of spawning behavior (HH:MM)" * End time: "End time of
 spawning behavior (HH:MM)" * Observation type: "Types of
 observed cases for each spawning event. F represents the entire observed
 spawning behavior, while P represents only a part of the observed spawning
 behavior." * Spawning duration: "Duration of spawning behavior
 (min)" * Sunrise time: "Sunrise time in Kagoshima, Japan
 (HH:MM)" * Sunrise to spawning time: "Time from sunrise to the
 start of spawning behavior (min)" NOTE: "NA"
 (non-applicable) is included in various columns to reflect instances in
 which we were unable to record the respective information for that
 variable. ### FILE Data female spawning interval.csv OVERALL DESCRIPTION:
 This file contains the results of the female spawning interval of
 Lubricogobius exiguus. COLUMN EXPLANATION * Pair ID: "Identification
 number of the breeding pair" * Female ID: "Identification number
 of female individual" * Spawning date: "Date of spawning
 (YYYY/MM/DD)" * Hatching date: "Date of egg hatching
 (YYYY/MM/DD)" * FSI: "Female spawning interval (day)" *
 HSS: "The days between hatching and subsequent spawning (day)"
 NOTE: "NA" (non-applicable) is included in various columns to
 reflect instances in which we were unable to record the respective
 information for that variable. ### FILE Data egg.csv OVERALL DESCRIPTION:
 This file contains data on the number of eggs from the breeding pairs of
 Lubricogobius exiguus. COLUMN EXPLANATION * Number of eggs: "Number
 of eggs in a cultch" * Average number of eggs: "Average number
 of eggs in a cultch" * Pair ID: "Identification number of the
 breeding pair" * Female ID: "Identification number of female
 individual" * Average female TL: "Average total length of female
 individual (mm)" * Male ID: "Identification number of male
 individual" * Average male TL: "Average total length of male
 individual (mm)" NOTE: "NA" (non-applicable) is included in
 various columns to reflect instances in which we were unable to record the
 respective information for that variable. ### FILE Data solitary
 individual.csv OVERALL DESCRIPTION: This file contains data on the
 solitary individuals of Lubricogobius exiguus. COLUMN EXPLANATION *
 Individual ID: "Identification number of individual" * Solitary
 period: "Solitary period in each individual (day)" * GMSS:
 "Gonadal morphological stage of solitary individual at the start of
 solitary status (NOS, non-developed ovary stage; DOS, developing ovary
 stage; MOS, matured ovary stage)" * GMSE: "Gonadal morphological
 stage of solitary individual at the end of solitary status (NOS,
 non-developed ovary stage; DOS, developing ovary stage; MOS, matured ovary
 stage)" * TND: "Time of transitions from NOS to DOS in solitary
 individual (day)" * TNM: "Time of transitions from NOS to MOS in
 solitary individual (day)" * COS: "Causes of the onset of
 solitary status in solitary individuals. Male refers to the disappearance
 of the male in the pair, female refers to the disappearance of the female
 in the pair, and unknown refers to individuals that were in a solitary
 state from the start of the observation." * CES: "Causes of the
 end of solitary status in solitary individuals. Recruitment refers to
 other individual recruiting to the nests, while disappearance refers to
 the disappearance of a solitary individual." * GMSR: "Gonadal
 morphological stage of recruited individual (NOS, non-developed ovary
 stage; DOS, developing ovary stage; MOS, matured ovary stage)" *
 PCFS: "The period from the day the recruited individuals and former
 solitary individuals cohabited to the first day of spawning (day)" *
 Pair ID: "Identification number of pair of solitary individuals that
 paired with recruited individuals" NOTE: "NA"
 (non-applicable) is included in various columns to reflect instances in
 which we were unable to record the respective information for that
 variable. ### FILE Oyama et al. ethology R.cord OVERALL DESCRIPTION: This
 file contains the R script to perform the analyses and generate the
 figures in this study. ## Code/software All statistical analyses were
 performed using the R version 4.4.0 software (R Core Team 2024). R Core
 Team. 2024. *R: a language and environment for statistical computing.* R
 Foundation for Statistical Computing, Vienna, Austria. Available at
 [https://www.R-project.org/](https://www.R-project.org/)