My research broadly focuses on the constant individual differences in behavior, also known as animal personalities, and their relationship with other phenotypic traits such as the structures individuals build or their morphology.
How does experience a different time-points influence trait variation over biologically relevant timescales?
How do multiple traits, such as the aggressive behavior of a spider and the web it builds, interact to influence fitness?
What mechanisms contribute to the maintenance of variation over time?
Individual variation in animal architecture
A host of animals build structures, from ant nests, bee hives, spider webs, and beaver dams, and these structures mediate a host of fitness-related process, from foraging, to rearing offspring, to defense. While plasticity in these structures has long been acknowledged, the concepts of consistent among-individual variation in these structures has been overlooked, despite the potential consequences of such variation.
My work demonstrates that individuals' do indeed vary in the structures they build. For example, in the western black widow, some individuals invest more in protective elements of their webs, while others invest more in elements that that increase foraging effictiveness (DiRienzo & Montiglio 2016). Such individual variation suggests that animals may make tradeoffs in the architecture of the structures they build, and that this variation may impact and interact with behavior and therefore fitness (Montiglio & DiRienzo 2016).
25% of obseverd behavioral variation is due to differences in web structure (Montiglio & DiRienzo 2016)
Evolution of phenotypic integration
While individuals vary in both behavior and the structures they build, the reason for these traits to correlated is often poorly understood. Presumably, the structure may facilitate behavior in some optimal way, although rarely is this type of interaction tested.
Widow spiders make a great model to test the functional interdependence of multiple traits as one can easily modify their web, or even give them an entirely new web that is built by a conspecific and differs in structure. One experiment leveraged this to see how changes in foraging web components interacted with foraging behavior to determine success. The results showed that behavior and web structure are indeed codependent, as individuals performed best when the structure 'matched their behavioral phenotype.
Web, behavior, or both?
Is the spider's success in the video is from it's behavioral response to the prey, the web retaining the ant, or a combination of the two?
The role of developmental experience in shaping the adult phenotype
A major question is how experience, particularly during ontogeny, shapes long term patterns of behavior. Using the western black widow, Latrodectus hesperus, myself, and Pierre-Olivier Montiglio demonstrated that prey availability during ontogeny has dramatic influences on life history, and subsequently adult behavior and web structure. Food restricted females take a 'fast' life history strategy, where they at a smaller size and maintain an aggressive behavior and web phenotype as adults, relative to females not food restricted during development. These differences are highly stable, and are maintained across changes in body condition. Thus, in this system, developmental experience plays a significant role in shaping the stable adult behavioral and web phenotype.
My other work with the field cricket, Gryllus integer, has highlighted that different types of interactions as a juvenile have different impacts on both mean behavior and the variance among and within individuals. Social cues, for example, affect the mean level of aggression, while juvenile pathogen exposure instead drives high levels of variation within-individuals. Current work is directed at exploring why different cues as juveniles have different effects as adults (e.g. mean vs. variance) and the associated consequences of these responses.
Body size difference in spiders reared under food restriction (right) vs. ad lib (left). Restricted spiders are more aggressive, and build webs structured for foraging, not safety, relative to ad lib spiders
Context dependent interactions and the maintenance of personality
Context dependent interactions may be critical to maintaining individual differences in behavior over evolutionary time. My research focused on how this may be accomplished via interactions between different personalities in a predator-prey context. Using the field cricket Gryllus integer as prey, and the western black widow Latrodectus hesperus as a predator, I demonstrated that different combinations of interaction personalities have different outcomes. Similar personality combinations, had higher probability of the prey being captured than combinations of opposing personalities. Thus, the fitness associated with a personality type depends on the personality types they're interacting with.
Encountering the wrong personality: Survival depends not only on your personalty type, but also that of who you interact with.