The Influence of Population and Community Variables on Bluegill, Lepomis Macrochirus, Life Histories: Implications for Growth Rates, Timing-of-Maturation, and Population Size Structure

Vertebrate life histories are complex and can be shaped by myriad population- and community-level variables. I conducted a series of experiments to examine aspects of bluegill, Lepomis macrochirus, life histories in an attempt to quantify variables influencing growth and maturation rates of individuals, and to examine the individual- and population-level consequences of variable life-history strategies. First, I examined the relative contribution of genetic and environmental variables to growth and maturation rates of individual male bluegill, and found that the timing of maturation is not predetermined genetically, but responds facultatively to the social structure of the extant population. To better understand cues associated with these social interactions, I conducted an experiment to isolate potential visual, chemical, and physical cues associated with spawning individuals. Results from this experiment suggest that chemical cues exuded by mature males are responsible for inhibiting maturation of juvenile male bluegill. To more closely examine mechanisms associated with growth and maturation of bluegill, I conducted a pond experiment to determine the ways in which resource availability and timing-of-maturation, interact to influence bluegill population size structure. I determined that density-dependent and early-maturation mechanisms interact in sex-specific ways to influence growth rates and maturation of bluegill, and that early maturation can impose a body-size cost due to the energetic tradeoff between somatic tissue growth and gonad maturation. To examine the fitness consequences that might result from variable life-history strategies, I compared the reproductive ecology of bluegill in established stunted and non-stunted populations, and found that individual body size can have a marked influence on the reproductive ecology of male bluegill. At the community level, I examined interactions between bluegill and gizzard shad (Dorosoma cepedianum) across 20 reservoirs to determine direct and indirect effects of gizzard shad on bluegill population size structure. Results from this examination indicated that the presence of gizzard shad can be associated with reduced bluegill growth rates and adult size structure. Combined, these experiments demonstrate the complex nature of individual life histories and elucidate important mechanisms that shape population size structure by influencing growth and maturation rates of individuals.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecology, Ethology, and Evolution

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Aday, Derek D.

Contributors dc:contributor

• Wahl, David H.
• Philipp, David P.

• Biology, Zoology

Language dc:language

eng

Identifier

(MiAaPQ)AAI3070249

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87009