Mating permissiveness in two congeners of live

bearing fishes

Jessica Bautista*, Brittni Broca, Dr. Raelynn Deaton Haynes

St. Edward’s University

Hybridization

Introduction

Gambusia

Large genus ~40 species

Live-bearing fish

Focus on G. affinis and G. geiseri

Gambusia affinis

Gambusia geiseri

Overview

Objective-To see whether increasing the species ratio and the density of the females will increase permissiveness in male behavior

Hypothesis-Permissiveness will increase with the density of the females and as species ratio changes

Methods

Species Male Behaviors Female Behaviors

Gambusia affinis Gonopodial Display

Copulation Attempt

Swim on BottomSwim AwayAllow Mating

Gambusia geiseri Gonopodial Display

Copulation Attempt

Swim on BottomSwim AwayAllow Mating

Methods/Experimental Design

Methods/Experimental Design

Experimental Design

Forced Choice Design

Open Choice Design

Control (Experiments 1-4)

G. geiseri male

G. geiseri female

G. geiseri male

G. affinis female

G. affinis male

G. geiseri female

G. affinis male

G. affinis female

1 2

3 4

Part 1 (Experiments 5-8)

G. geiseri female x 2

G. geiseri male

G. affinis male

G. affinis male

G. affinis female x 2

G. geiseri female x 2

G. affinis female x 2

G. geiseri male

5 6

7 8

Results Slide

Experiments

Av

era

ge

Go

no

po

dia

l Dis

pla

y

0

1

2

3

4

5

6

G.geiseri-G.geiseri G.affinis-G.affinis G.affinis-G.geiseri

p>0.05

p<0.05

p>0.05

N=22N=30

N=30

Kruskell Wallace

Results Slide

Experiment

Av

era

ge

Co

pu

latio

n A

ttem

pt

0

2

4

6

8

10

G.geiseri-G.geiseri G.affinis-G.affinis G.affinis-G.geiseri

p>0.05

p>0.05

p<0.05

N=22

N=30

N=30

Kruskell Wallace

Results Slide

Experiment

Mean

Male

Beh

avio

rs

0

2

4

6

8

10

G.affinis-G.affinis G.affinis-G.affinisx2

Mann Whitney U, df = 25, p=0.164

Mann Whitney U-test Purple-Gonopodial

Display Red-Copulation Attempt

Summary of Results

First finding: male G. affinis seem to prefer the heterospecific (did not support our predictions)

This may be due to the Novelty Effect

Second finding: G. affinis males increase mating behaviors as you add females (supports our predictions)

Significance and Future Work

Spring, G. nobilis

Significance Hybridization Conservation

Acknowledgements

St. Edward’s University

TG Public Benefit Grant Program

Dr. Raelynn Deaton Haynes

Brittni Broca

Dr. Richard Kopec

Michael Lykaios

Valerie Mejia

James Stewart

Jacqueline Chisholm

Questions?