DOI: 10.5061/dryad.hhmgqnkrc
title: Sexual selection and predator response in a male-polymorphic livebearing fish

description: Sexual polymorphism describes discrete variation among individuals of one
 sex, often involving conspicuously colored, displaying male morphs and
 inconspicuous, sneaking male morphs. Sexual polymorphism may be maintained
 over evolutionary time if the displaying morph is favored by sexual
 selection and the sneaking morph experiences reduced predation. We tested
 these ideas using 3D printed models and live males in the sexually
 polymorphic poeciliid fish, Girardinus metallicus. Females did not prefer
 the displaying black morph; however, black morphs exhibited more male-male
 aggression, and dominant black morph males achieved higher mating success
 than all plain morph males, suggesting a sexual selection advantage.
 Predatory blue tilapia (Oreochromis aureus) did not show a preference for
 either morph, suggesting no plain morph advantage in this regard that
 would maintain the polymorphism. It is possible that the polymorphism is
 instead maintained because as black morphs become common, aggressive
 interference among them causes their fitness to decline, thereby keeping
 black morphs rare relative to plain morphs, but not eliminating them
 entirely. Our results underscore the need to further explore the function
 of the black morph display, as it appears not to be sexually selected via
 female choice, in contrast to mating displays in similar species.
description: Data were collected by direct observation for behaviors and
 measurement from digital images for body size. Data analysis was performed
 using JMP Pro 17.
description: # Sexual selection and predator response in a male-polymorphic livebearing
 fish
 [https://doi.org/10.5061/dryad.hhmgqnkrc](https://doi.org/10.5061/dryad.hhmgqnkrc) ## Description of the data and file structure These data were collected for an experimental study examining sexual selection and predator reaction comparing the two male morphs of the poeciliid fish, *Girardinus metallicus. *We employed dichotomous choice tests and direct interaction tests to quantify sexual selection across morphs, and dichotomous choice tests to quantify the reaction of blue tilapia (*Oreochromis aureus*) to males of each morph. 1\. Title of Dataset: Sexual selection and predator response in a male-polymorphic livebearing fish 2\. Author Information A. Principal Investigator Contact Information Name: Gita R. Kolluru Institution: California Polytechnic State University Address: San Luis Obispo, CA USA Email: [gkolluru@calpoly.edu (opens in new window)](mailto:gkolluru@calpoly.edu) 3\. Date of data collection: 2016-2018 4\. Geographic location of data collection: California Polytechnic State University, San Luis Obispo, CA USA ### Files, variables and JMP code #### File: 3D\_model\_dichotomous\_choice\_data.csv **Description:** Data collected during dichotomous choice trials with 3D printed models of males of each morph as stimuli. Cells with "n/a" indicate cases where data were inadvertently either not collected or lost subsequent to collection. ##### Variables * Female Stock: the stock of origin, either recently acquired versus long captive stock * Trial Number: indicating whether it was the first or second trial in which the female was tested with a specific pair of males * Female ID: unique identifier for each female tested * Side model was on: side the model was on during 3D model dichotomous choice trials (called "Model side" in the code below) * Female Mass (g): mass of the female * Stance (Is black morph model in display stance in this pairing?): referring to whether the black morph model in the pair was in the displaying stance or not * Model Morph: morph of the 3D printed model * Interaction zone time (s): time spent by the female in the interaction zone during dichotomous choice trials - Association zone time (s): time spent by the female in the association zone during dichotomous choice trials ##### JMP Code Fit Model( ``` Y( :"Box Cox[MODEL Association (s)]"n, :"Square Root[MOD...nteraction (s)]"n ), Effects( :Female Stock, :Black morph in display stance in this pairing?, :Model Morph, :Black morph in display stance in this pairing? * :Model Morph, :Model Side, :Model Morph * :Female Stock, :"Female Mass (g)"n, :Trial Number ), Random Effects( :Female ID[:Female Stock] ), Keep dialog open( 1 ), Fit Separately( 1 ), Personality( "Standard Least Squares" ), Emphasis( "Minimal Report" ), Method( "REML" ) ``` ); #### File: Live\_male\_dichotomous\_choice\_data.csv **Description:** Data collected during dichotomous choice trials with one plain morph male and one black morph male presented as stimuli. Cells with "n/a" indicate cases where data were inadvertently either not collected or lost subsequent to collection. One group (Group ID 22) was excluded from analysis because both males were equally aggressive, and therefore could not be assigned a dominance status. However, we include that group's data in the file for completeness. ##### Variables * Group ID: a unique identifier for each pair of one plain morph male and one black morph male * Male-Female Pair ID: a unique identifier for the female and one of the males in the pair that was tested together in live male dichotomous choice and direct interaction tests; this is necessary because there is one line of data per male despite the males being tested in pairs * Trial Number: indicates whether it was the first or second trial in which the female was tested with a specific pair of males * Dominance Status per female (Trial 1 + 2): a categorical dominance status across trials, assigned to each male within a pair based on the proportion of the total aggressive behaviors exhibited by the pair that were performed by that male; equation provided in the paper * Female Stock : the stock of origin, either recently acquired or long captive stock * Male Stock: the stock of origin, either recently acquired or long captive stock * Male Morph: morph of the male * Female Mass (g): mass of the female * Male Mass (g): mass of the male * Association Time (s): time spent by the female in the association zone during dichotomous choice trials - Interaction Time (s): time spent by the female in the interaction zone during dichotomous choice trials ##### JMP Code Fit Model( ``` Y( :"Association Time (s)"n, :"Square Root[Int...ction Time (s)]"n ), Effects( :Male Stock, :"Dominance Status per female (Trial 1 + 2)"n, :Male Morph * :"Dominance Status per female (Trial 1 + 2)"n, :"Male Stock (recently acquired/long captive)"n, :"Female Mass (g)"n, :"Male Mass (g)"n, :"Female Stock (recently acquired/long captive)"n, :Trial number, :"Female Stock (recently acquired/long captive)"n * :Male Morph ), Random Effects( :"Male-Female Pair ID"n[:Group ID], :Group ID ), Personality( "Standard Least Squares" ), Emphasis( "Minimal Report" ), Method( "REML" ) ``` ); #### File: Direct\_interaction\_data.csv **Description:** Data collected during direct interaction trials involving one plain morph male, one black morph male, and one female. Cells with "n/a" indicate cases where data were inadvertently either not collected or lost subsequent to collection. One group (Group ID 22) was excluded from analysis because both males were equally aggressive, and therefore could not be assigned a dominance status. However, we include that group's data in the file for completeness. ##### Variables * Group ID: a unique identifier for each pair of one plain morph male and one black morph male * Dominance Status per female (Trial 1 + 2): a categorical dominance status across trials, assigned to each male within a pair based on the proportion of the total aggressive behaviors exhibited by the pair that were performed by that male; equation provided in the paper * Male-Female Pair ID: a unique identifier for the female and one of the males in the pair that was tested together in live male dichotomous choice and direct interaction tests; this is necessary because there is one line of data per male despite the males being tested in pairs * Trial Number: indicates whether it was the first or second trial in which the female was tested with a specific pair of males * Follows Female (s): time spent by the focal male swimming relatively slowly towards the female * Mating Display to Female (s): time spent by the focal male swimming towards the female with gonopodium and dorsal fin extended and head tilted up * Male Morph: morph of the male * Female Stock: the stock of origin, either recently acquired versus long captive stock * Male Stock: the stock of origin, either recently acquired versus long captive stock * Female Mass (g): mass of the female * Male Mass (g): mass of the male * Copulation Attempts WITHOUT Contact: number of copulation attempts during which the gonopodium tip did not make visible contact with the female * Copulation Attempts WITH Contact: number of copulation attempts during which the gonopodium tip made visible contact with the female * Sum of Following and Mating Display to Female (s): the sum of the time spent by the focal male swimming relatively slowly towards the female and swimming towards the female with gonopodium and dorsal fin extended and head tilted up; this was necessary because black morphs follow while displaying, whereas plain morphs follow without displaying * Chases Female: focal male swims very quickly towards the female * Chases Male: focal male swims very quickly towards the other male * Bites Female: visible contact between mouth of focal male and body of the female * Bites Male: visible contact between mouth of focal male and body of the other male * Blocks: number of times a displaying male was interrupted by the rival male attempting to approach the female, during which the focal male successfully retained access to the female * Gonopodial Jabs to Male: visible contact between the gonopodium of the focal male and the body of the other male * Gonopodial Display to Male (s): duration of display during which the focal male extends the gonopodium and dorsal fin and exhibits lateral surface to the other male, without tilting the head up - Follows Male (s): time spent by the focal male swimming relatively slowly towards the other male ##### JMP Code Fit Model( ``` Y( :Factor1 Mating activity, :"Box Cox[Factor4...ale aggression]"n, :Factor2 Chases male and female ), Effects( :"Male-Female Pair ID"n[:Group ID] & Random, :Group ID & Random, :Male Morph, :"Male Stock (recently acquired/long captive)"n, :"Female Stock (recently acquired/long captive)"n, :"Female Stock (recently acquired/long captive)"n * :Male Morph, :"Male Stock (recently acquired/long captive)"n * :Male Morph, :Trial number, :"Dominance Status per female (Trial 1 + 2)"n, :"Dominance Status per female (Trial 1 + 2)"n * :Male Morph, :"Dominance Status per female (Trial 1 + 2)"n * :"Male Stock (recently acquired/long captive)"n, :Male Morph * :"Dominance Status per female (Trial 1 + 2)"n * :"Male Stock (recently acquired/long captive)"n, :"Female Mass (g)"n, :"Male Mass (g)"n ), Keep dialog open( 1 ), Personality( "Standard Least Squares" ), Method( "REML" ) ``` ); #### File: Comparison\_of\_studies.csv **Description:** Comparison of data collected during direct interaction trials for Wojan et al. (2018) versus the present study. For the variable "Proportion of copulation attempts with contact", cells with "n/a" indicate cases where there were no copulation attempts, and so this variable was not able to be estimated. For other variables, cells with "n/a" indicate cases where data were inadvertently either not collected or lost subsequent to collection. ##### Variables * Study: whether the study was Wojan et al. (2018) or the present study * Study Type: whether the study competed two black morphs (Wojan et al. 2018) or one plain and one black morph (present study) * Male Morph: morph of the male * Male ID: unique identifier for each male tested * Pair or Group ID: a unique identifier for either each pair of black morphs (Pair ID; Wojan et al. 2018) or each pair of one plain morph and one black morph (Group ID; present study) * Trial Number: indicates whether it was the first or second trial in which the female was tested with a specific pair of males * Copulation Attempts with contact: number of copulation attempts during which the gonopodium tip made visible contact with the female * Copulation Attempts without Contact: number of copulation attempts during which the gonopodium tip did not make visible contact with the female * Proportion of Copulation Attempts With Contact: number of copulation attempts with contact divided by the total number of copulation attempts (with and without contact) * Male standard Length (mm): the distance from the tip of the closed snout to the posteriormost arc of the caudal peduncle * Male mass (g): mass of the male ##### JMP Code Fit Model( ``` Y( :Copulation Attempts with contact, :Proportion of copulation attempts that made contact ), Effects( :Study Type, :Trial Number, :"Male mass (g)"n, :Male ID[:Pair or Group ID] & Random ), Keep dialog open( 1 ), Personality( "Standard Least Squares" ), Method( "REML" ) ``` ); #### File: Predator\_reaction\_data.csv **Description:** Data collected during dichotomous choice trials of blue tilapia presented with one plain morph male and one black morph male as stimuli. Cells with "n/a" indicate cases where the tilapia did not enter a choice zone, and so some variables could not be estimated. ##### Variables * Trial Number: indicates whether it was the first or second trial in which the tilapia was tested with a specific pair of males * Tilapia Sex: sex of the tilapia * Tilapia Standard Length (mm): distance from the tip of the closed snout to the caudal peduncle line * Latency between partition removal and tilapia entering zone (s): time between when the opaque partition was removed and when the tilapia entered a choice zone * Morph first approached: the *G. metallicus* morph first approached by the tilapia * Side first approached by tilapia: the side of the *G. metallicus* tanks first approached by the tilapia (called "GM male side" in the code below) * *Girardinus metallicus* Pair ID: a unique identifier for each pair of one plain morph male and one black morph male tested * *Girardinus metallicus* ID: a unique identifier for each male *G. metallicus *that was tested * *Girardinus metallicus* Male Morph: the morph of the male tested * *Girardinus metallicus* Male Side: which side the male was on during the trial * *Girardinus metallicus* Male Mass (g): mass of the male * *Girardinus metallicus* Male Standard Length (mm): the distance from the tip of the closed snout to the posteriormost arc of the caudal peduncle * Tilapia ID: a unique identifier for each tilapia individual tested * Association time (s): the total time spent in the association zone of a particular male ##### JMP Code Fit Model( ``` Y( :"Log[A...ation time (s)]+1"n ), Effects( :GM ID[:GM Pair ID] & Random, :Trial Number, :Tilapia Sex, :"Tilapia Standard Length (mm)"n, :GM Male Morph, :GM Male Side, :GM Male Morph * :GM Male Side ), Keep dialog open( 1 ), Personality( "Standard Least Squares" ), Method( "REML" ) ``` );