Genetic mating system and mate selection in smallmouth bass.

Ryan P. Franckowiak,Chris C. Wilson,Mark S. Ridgway

doi:10.1002/ece3.3423

Abstract

Mating systems are an important factor influencing the variance in reproductive success among individuals within natural populations and thus have important ecological and evolutionary implications. We used molecular pedigree reconstruction techniques with microsatellite DNA data to characterize the genetic mating system and mate selection in adult smallmouth bass spawning in Lake Opeongo. The genetic mating system of smallmouth bass in this system can be characterized as predominantly monogamous with a low rate of polygynandry particularly among larger individuals. Iteroparous individuals showed a complete absence of interannual mate fidelity, presumably due to the low annual return rate of spawning adults. Within a season, individuals from both sexes pursued additional mating opportunities with males showing greater variance in mate number than females. Female mate selection appeared to be largely random with little evidence for elevated levels of inbreeding in this population. Multiple mating females pursued additional males to whom they were less related than the first male with which they spawned within a given season, however, this pattern varied among years. The mating pattern observed in this population would likely limit the strength of sexual selection and thus could account for the lack of sexual dimorphism and the absence of alternative reproductive tactics in this species.

Highlights

Animal mating systems are exceptionally diverse, and considerable effort has been undertaken to document and describe variation in mating systems among taxonomic groups, to identify the factors leading to and maintaining this variation, and to understand the ecological and evolutionary implications of different mating systems (Davies, 1991; Emlen & Oring, 1977; Shuster & Wade, 2003)
Uniparental care displayed by smallmouth bass provides an opportunity for both males and females to pursue additional mates, and yet the majority of broods produced within any given breeding season were the result of single-pair mating. This suggests the environmental potential to participate in multiple mating is either nonexistent for these individuals or that behavioral or physiological constraints may limit their ability to take advantage of this potential (Emlen & Oring, 1977; Shuster & Wade, 2003)
The inability of male smallmouth bass to fully capitalize on the environmental potential for polygamy due to either ecological or behavioral constraints may in part explain the lack of sexual dimorphism or the absence of alternative reproductive tactics (Ridgway, 1989) often seen in other centrarchids (DeWoody et al, 1998; Gross, 1984, 1991; Neff & Clare, 2008; Neff, Fu, & Gross, 2003)

Summary

| INTRODUCTION

Animal mating systems are exceptionally diverse, and considerable effort has been undertaken to document and describe variation in mating systems among taxonomic groups, to identify the factors leading to and maintaining this variation, and to understand the ecological and evolutionary implications of different mating systems (Davies, 1991; Emlen & Oring, 1977; Shuster & Wade, 2003). With increasing variance in habitat quality, there exists a greater potential for individuals to monopolize resources, and a greater environmental potential for polygamy, and sexual selection is expected to intensify (Emlen & Oring, 1977; Shuster & Wade, 2003). Males display strong nest site fidelity (Ridgway, MacLean, & McLeod, 1991; Ridgway, Shuter, Middel, & Gross, 2002) and are presumed to exhibit strong philopatry to natal nesting areas (Gross, Kapuscinski, & Faras, 1994) These behaviors are expected to concentrate relatives during reproduction and thereby increase the probability of mating between closely related individuals. The purpose of this study was to examine the causal factors regulating genetic mating systems and reproductive tactics in a centrarchid species To this end, we characterized the genetic mating system of smallmouth bass in Lake Opeongo. We examined the genetic relatedness of male–female spawning pairs to assess whether female smallmouth bass actively avoid mating with close relatives

| MATERIALS AND METHODS

| DISCUSSION

Findings

| SUMMARY