A brown anole (Anolis sagrei) surveys its domain.
Trophic ecology deals with questions about the ways in which organisms acquire energy and how that process interacts with the communities and ecosystems surrounding them. Anole-focused research has played a strong role in our understanding of trophic ecology and ideas abut how communities come together and evolve, particularly in papers by Schoener, Roughgarden, and Lister. However, many trophic ecology studies have focused on specific communities or locations and haven’t dealt with how the ecology of one focal species varies across space and as a function of the presence of other close competitors.
Sean Giery, a post-doc at the University of Connecticut, in collaboration with James Stroud, a post-doc at Washington University in St. Louis, worked to address this gap in our knowledge by studying how the trophic ecology of the brown anole, Anolis sagrei, varies across its range. Brown anoles are voracious predators of insects, known to chow down on a diverse range of arthropods, including some of surprising size. Since the brown anole is also a prodigious invader, it occupies habitats with a variety of potential competitors, including locations with few competitors. Sean and James leveraged this situation to their advantage by compiling stomach content data from previously published papers (including a follow-up on Lister’s paper above). They also added their own sampling, including in Southern Florida, the Bahamas, and Hawaii…tough work! Sean and James then used the articles themselves, field guides, and citizen science sources like iNaturalist to determine the presence of other species which might compete with the brown anole, including other anoles and diurnal, insectivorous lizards.
Sean and James assembled an impressive database of the diet of A. sagrei.
They found that as community richness increases, the dietary niche of A. sagrei actually becomes broader, the opposite of the direction predicted by theories of ecological release. Additionally, average niche overlap between individual anoles declines as community richness increases. When only brown anoles are present in a community, individuals are highly similar in the types and proportions of what they eat, another finding which runs counter to models of how niche breadth should vary when a species is released from interspecific competition. Sean concluded his talk by suggesting that interference competition may be more important than generally recognized and soliciting suggestions for ways to continue looking at this impressive dataset. We’ll look forward to reading the paper!
Skip Lazell
Me too! When all alone my dietary spectrum narrows down to a few items; when living in a group, the spectrum broadens dramatically. Very anoline! Skip