Year of Award

2007

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Organismal Biology and Ecology

Department or School/College

Division of Biological Sciences

Committee Chair

Douglas J. Emlen

Commitee Members

John H. Christy, Erick P. Greene, Thomas E. Martin, John L. Maron, Timothy A. Mousseau

Keywords

allometry, behavior, Coreidae, evolutionary ecology, maternal effects, sexual selection

Abstract

The early environment experienced by organisms can have significant phenotypic effects that persist throughout life. Parents, mothers in particular, commonly determine these early environments. Maternal effects, or the influence of maternal phenotypes on offspring phenotypes, are therefore likely ubiquitous in natural populations. However, the frequency and evolutionary consequences of maternal effects are largely unknown. Here I show that maternal phenotypes can have large effects on offspring morphology, fecundity, and behavior. I theoretically explore the potential for these effects to resolve the long-standing "lek paradox" in the field of sexual selection. I also empirically investigate these effects in the heliconia bug, Leptoscelis tricolor. Females heliconia bugs lay eggs on several species of heliconia plants in Panama and Costa Rica. Host plant species choice by mothers largely determines the natal environment that offspring will experience due to the limited mobility of juveniles. Insects that emerged on one species of heliconia, Heliconia platystachys, were larger, and males expressed relatively larger secondary-sexual traits for their body size than those raised on H. mariae. The mating probability and fecundity of female offspring was higher on H. platystachys. Furthermore, males raised on H. platystachys performed a faster rate of copulatory courtship while mating and also boosted this rate when mating with females from H. platystachys. Such copulatory movements may enhance male and female reproductive success. While host plant species choice by mothers had significant maternal effects on offspring overall, the consequences for offspring varied with time. Mothers that laid eggs on H. platystachys early in the wet season produced large, fecund offspring in good phenotypic condition. This maternal effect gradually changed until, later in the season, sons and daughters raised on H. platystachys were smaller and daughters laid few or no eggs and did not mate. Thus, at some times H. platystachys appeared to be a much superior host plant for offspring, while at other times, H. mariae was better. Dynamic consequences of maternal behaviors (here, host plant species choice) for offspring have only rarely been explored and may have far-reaching consequences for the evolution of maternal and offspring traits.

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© Copyright 2007 Christine Whitney Miller