The animal kingdom contains staggering morphological diversity, but even greater behavioral diversity. All animals display species-specific ecological behaviors (such as preferentially interacting with members of the same species), and behavior alone can distinguish species that are otherwise morphologically identical - e.g., cricket species that inhabit the same environment and are distinguished only by distinct mating songs. Evolution and behavior influence each other - evolution can diversify or purify behavior; behavior determines fitness and population structure.
The goal of our lab is to understand the mechanisms of ecologically and evolutionarily relevant behavioral variation using techniques drawn from circuit neuroscience, genetics and genomics, and computational ethology. We use insects to do this work, particularly the fruit fly Drosophila melanogaster, because of its incredible genetic toolkit and experimental versatility.
One can consider behavioral diversity at several scales. Arthropods may on average behave differently than vertebrates - sister species differ behaviorally either by drift or selection for mating isolation - the behavior of strains within a species may vary due to differential allelic frequencies or phenotypic plasticity - and genetically identical siblings display non-heritable behavioral differences. In humans, this is called personality.
We have found that even in isogenized stocks of fruit flies, individuals display idiosyncratic behaviors in a number of paradigms. In all strains tested, within clonal siblings, individuals show variation in photo-positivity or photo-negativity, as measured by whether they run toward light or darkness when startled. While not showing a species-level bias, individual flies prefer to choose either left or right turns in branching mazes. These idiosyncrasies are not heritable, but last the lifetime of the flies, and therefore constitute a form of personality.
The modularity of developmental signaling pathways appears to be essential for the generation of diverse animal forms through evolution by natural selection. Rather than evolve new genes and signaling pathways to generate a wing or antenna from scratch, it is sufficient to reuse the modular signaling pathways that generate limbs, particularly since each insulated pathway typically controls an independent physical parameter of development, such as limb length, width, or number of segments. Could behavioral modularity be analogously utilized in the generation of behavioral diversity?
We address this question using dimension-reducing analytic methods on high-resolution temporal and spatial data of single flies performing spontaneous walking behavior on floating balls.
