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 will respond differently to various social environments.
Forked fungus beetles are a sexually dimorphic beetle species that live and feed on the shelf fungus of fallen, decayed logs. Fungus varies in quality within populations and may be a factor driving behaviors responses among beetles on a log. Females use this fungus for egg-laying. Hatched larva live and feed inside the fungus as they grow… even cannabalizing other larva they run into as they develop! Males perform characteristic courting and competitive behaviors that are important components of a male’s fitness in this species. My research asks if the sexes differ in behavioral plasticity of aggressive and non-aggressive behaviors between various social contexts and if these differences result in fitness consequences in the wild.
If animal behaviors are repeatable across environments, then we would expect fitness to consequently differ across those environments. While behavior is the most plastic phenotype at an animal’s disposal, a proporation of many behaviors are repeatable in response to different social cues. Behaviors in forked fungus beetles are no exception! Male aggressive and non-aggressive behaviors are highly repeatable based on laboratory assays where male behaviors were observed when paired with a same-sex competitor (Mitchem et al. 2019). Moreover, larger, more aggressive males are more likely to win male-male competition in these same laboratory assays. 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.
More fascinating is the lack of repeatablity in female behaviors during same-sex competition trials. Using the same behavioral paradigm as the male-male competition study, I observed females performing the same behaviors as males, but none of these behaviors were performed in an aggressive context and no behaviors were repeatable across trials. The behaviors that a female performs with one same-sex partner is not indicative of how she will perform with another same-sex partner.
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 must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses that fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. With the help of an amazing REU, Zorimar Vilella-Pacheco, I performed a series female choice trials that allowed females to assess the chemical cues of males before and after male-male competition. Overall, females preferred to associate with the chemical cues future losing males before male-male competition but switched their preference to winners after competition. A male’s past competitive experiences are an important contexts for females assessment and is potentially important for determining which males will have access to mates.