Collaborative Research: Expression and dynamics of reproductive tactics in a wild population of smallmouth bass

Bowling Green State University, Bowling Green OH

Investigators

Abstract

In many animals, reproducing males fall into distinct categories and the males in these categories can look quite different from one another. The hooknose and jack males in salmon populations are well-known examples, where hooknose males are big and aggressive while jacks are small and inconspicuous. These males exhibit what are called alternative reproductive tactics. Alternative reproductive tactics are typically not genetically inherited. They can depend on the environmental conditions a male experienced as he developed. The behavior of parents sometimes determines the tactic a male adopts and parental behavior can even cause their young to express the tactic opposite that of their parents. In general, alternative reproductive tactics are not well understood because it is difficult to follow multiple generations of animals and determine the conditions under which individuals develop before they reach adulthood. Project researchers will identify causes of alternative tactic expression in smallmouth bass - an economically important sport fish - from a previously collected, decade-long dataset where multiple generations of males were followed and detailed information on individual reproductive behavior was documented. Paternity analysis will identify fathers, sons, and grandsons and developmental conditions and individual growth will be determined from environmental data and scales which, like tree rings, record growth histories. Undergraduates from underrepresented groups in STEM and graduate students will be trained in genetics, genomics, bioinformatics and fisheries techniques. Results will be shared through an animated video made publicly available and distributed to resource managers and others to display where fishing licenses are sold. The realization that many, perhaps most, alternative reproductive tactics, or ARTs, depend on individual condition sparked a general interest in the proximate control of tactic expression and the ultimate control of tactic frequencies within populations. How ARTs coexist within a population is an evolutionary puzzle that is only partially resolved. ARTs were hypothesized to result from genetic differences amongst individuals, balanced by frequency-dependent selection, but appear to more generally depend on the developmental conditions an individual has experienced. ARTs fit into a broader category of investment strategies, which includes life history decisions, and are evolutionary solutions to reproductive competition that account for individual condition or status, products of an investment strategy that is contingent the social and environmental situations under which individuals have developed. In some instances, ARTs are controlled by non-genetic parental effects, which can influence the dynamics of ARTs and facilitate or impede adaptive evolutionary processes. Project researchers will detail ARTs in a population of smallmouth bass (Micropterus dolomieu) where a non-genetic parental effect is hypothesized to cause tactic alternation within lineages, across generations. To detail parent and offspring tactic choices and test the genetic basis of tactic polymorphism RADSeq from preserved tissue samples will be used to generate thousands of SNPs across the genome and paternity analysis will be applied to trace male tactic choices in 240-381 lineages, across 1-5 generations. Developmental conditions and growth histories will be determined from field data and scale samples to identify environmental factors that exert proximate control over the expression of tactics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.