I am currently a Ph.D. candidate in the Brodie lab at the University of Virginia studying Behavioral Ecology in Bolitotherus cornutus (forked fungus beetle). My research examines behavioral responses across social environments. I use manipulative methods in the lab and observations from natural settings to determine the extent to which individuals with respond differently to various social environments. My research tackles the following three topics:
Forked fungus beetles are a sexually dimorphic beetle species that live on the shelf fungus of fallen, decayed logs. Males perform characteristic courting behaviors that consist of a male mounting a female head to abdomen, copulating, then males guarding the female in a head to head position for many hours to ensure insemination success. Another male can pry a courting male from the female using its thoracic and clypeal horns. These courting and competitive behaviors are important components of a male’s fitness in this species. Larger, more aggressive males win more male-male interactions (Mitchem et al. 2019), likely gaining them more access to females. These aggressive behaviors, as well as other non-aggressive behaviors, are highly repeatable within the context of male-male interactions, but how plastic are these behaviors to changes in context? For example, will males who are aggressive during competition carry that aggression to mating? Do individuals with certain ‘personalities’ differ in their behavioral plasticity in response to social context? If so, what are the fitness consequences of this plasticity?
Less is known about female behaviors, but pilot studies show that females display many of the same behaviors as males. Females may use aggressive behaviors for competition over fungus for egg-laying, which can vary in quality within a population. Females also perform the same non-aggressive behaviors as males, but the fitness consequences of these behaviors are unknown in both sexes. My research additionally asked if the sexes differ in behavioral plasticity of aggressive and non-aggressive behaviors, and if these differences result in fitness consequences in the wild.
If animal behaviors are repeatable across environments, then we would expect fitness to differ across environments due to the various consequences of behaviors in different situations. Animals often possess personalities that are repeatable between different social contexts. Forked fungus beetles are no exception! Male aggression is highly repeatable (0.77) based on laboratory assays where male behaviors were observed when paired with a same-sex competitor. Image on the left depicts an ethogram of forked fungus beetle male-male interactions. Red behaviors are aggression, blue are non-aggressive, and purple are mounting behaviors. The size of bubbles indicates the frequency at which those behaviors are initiated, and the arrow width indicates the probability of one behavior transitioning to the next.
Chemical cues are one way for animals to assess the quality of potential competitors and mates. Animals may favor interactions with or change behaviors in response to specific individuals depending on chemical cues. In collaboration with Vincent Formica (Swarthmore College) and Alison Holliday (Moravian College), I am using chemical cues to assess an individual’s propensity to engage in interactions with conspecifics of certain phenotypes. Our current project asks if females prefer to associate with winners or losers of male-male competition, and if winners and losers differ in chemical composition.
Females prefer to associate with the chemical cues future losing males before male-male competition. However, male chemical composition changes after male-male composition and females prefer to associate with the chemical cues of ‘winning’ males. Females also prefer to associate with males who initiate more interactions during male-male competition (noted as ‘interactive’ in figure below), but this trend is only present after males interact. Females show no preference for ‘future interactive’ males.