Photo by Dr. Christine Miller
Research
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Having a suitable phenotype for the environment is crucial to survival and reproduction. Therefore, heritable traits that maximize survival and reproduction under local conditions are more likely to persist in a population. However, habitats are incredibly diverse and dynamic across space and time. Change can occur quickly, altering the direction or intensity of selection, and potentially changing the tempo of the evolutionary process. A central theme of my research is to understand the causes and consequences of variation in reproductive success under dynamic environments. I use insects to understand how nutrition and social interactions influence resource allocation decisions to pre- versus post-copulatory traits, behavioral decisions, and reproductive success.
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Novel vibrational signals in mating and fighting behaviorsVibrational communication is ecologically important to insects. Substrate-borne vibrations are commonly used by herbivorous insects to communicate species-specific information. I describe the substrate-borne vibrational signals associated with mating and fighting behaviors of the herbivorous red milkweed beetle (Tetraopes tetraphthalmus). Males dorsally mount females and begin copulation in <5 minutes. Prior to and during copulation, males can produce vibrational signals with their abdomens that females likely perceive as contact courtship. Males also engage in intraspecific competition for females and can use vibrations in their fighting repertoire. These vibrations intensify as fighting behavior intensifies.
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Does adult social information change female preferences?In mate choice, social learning may take the form of mate choice copying or anti-copying, whereby observed mating decisions are either mimicked or avoided. Alternatively, independent mating decisions may be based on innate preferences or early life social learning. While mate choice copying is widespread among some animal taxa, research in arthropods is limited and results are mixed. We tested these hypotheses using Enchenopa treehoppers that produce plant-borne vibrational advertisement signals and females express their mate preferences by selectively duetting with males. We found that female mate preferences were not affected by the treatment duets. Instead, females had consistent individual differences which supports the independent mate choice hypothesis and rejects both social learning hypotheses.
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Nutrition impacts female reproductionChanges in the nutritional environment can expose organisms to poor resource conditions. These poor conditions impose resource limitations on animals making it more difficult to partition resources to all life history traits equally. Often when resources are poor, organisms must reduce investment and allocation to certain traits and their functions. My work specifically focuses on how female reproductive traits are affected by nutritional changes and whether females can overcome a poor nutritional start in life with high quality nutrition later in life. Understanding how animals respond to nutritional changes is vital for understanding population growth, persistence of a species, and how species can cope with a changing environment.
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Weapon damage affects male fertilizationMales of many species engage in fighting behavior for access to females. Weaponry is often vital for success in these battles and ultimately helps males gain a fitness advantage. What happens to male fitness if a weapon is damaged? I explore this question using Narnia femorata, a leaf-footed bug that can naturally lose it's hind leg weapon when it is compromised. Males with a missing hind leg weapon (i.e. weapon damage) are less likely to win pre-copulatory competitions; however, when they do achieve matings, these males are able to enhance their fertilization success. I examine how this fitness advantage affects weapon-damaged males in a multiple mating scenario.
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Male reproduction is influenced by femalesSperm production is important to male fitness and sperm depletion can constrain the amount of offspring a male can produce. Males should be more apt to produce sperm in the presence of a high quality female (i.e. one that is large and fertile) and/or replenish sperm more quickly when subject to mating with many different females. In this collaborative project, we examined how female quality and quantity affects male testes size in the leaf-footed bug, Narnia femorata.
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Evolution of reproductive trade-offsMales that engage in pre-copulatory competitions use energetically costly weapons to secure territory or mates to enhance their reproductive success. What happens if a male damages his weapon and can no longer secure access to females? In leaf footed cactus bugs (Narnia femorata), males partition freed up resources to the gonads.This allows them to fertilize more eggs when they are able to mate, a trade-off whose evolutionary mechanisms are not currently known. Our large-scale collaborative project examines the evolution of reproductive trade-offs in the family Coreidae. We are investigating this phenomena in 14 different species to understand how this trade-off has evolved over time.
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