I am intrigued by the impact of morphological traits on ecological interactions and species divergence patterns. The widespread and diverse ant genus Polyrhachis is ideal for investigating these topics, with species boasting a broad range of morphological types, including some with highly developed spines. I will use this charismatic group to address patterns of trait evolution, including the impacts of “integration” on evolutionary rate and the ecological functions of spinescence.
Integration and Evolutionary Constraint
Morphological integration is the linkage of a set of morphological traits that together generate a more complex phenotype. Integration may drive increased adaptability and specialization, but it may also constrain the adaptability of a species to a particular region of morphospace, ultimately limiting the rate of speciation. Using standard and geometric morphometrics, I will investigate integration across species of Polyrhachis using) recently described methods that incorporate phylogenetic information and morphometric data, to determine the strength of covariance between subsets of traits across evolutionary timescales. I aim to address the following questions:
How does integration vary across clades in the Polyrhachis phylogeny?
Does integration constrain or promote morphological change over evolutionary time?
Do morphological integration and specialization limit the rate of speciation?
Adaptation and Function of Spines
(Image: Alex Wild)
Despite the prevalence of spines across a wide range of ants, the function of such spinescence (the number and length of spines) has never been rigorously tested. Spines are often simply assumed to serve as predator deterrence, but several other forces could potentially drive spine evolution, including intraspecific competition or even arial parasitoids. Furthermore, processes such as an ecological trade-offs may influence diversification and ecological interactions in this group.
I am developing methods for testing the function of spines in Polyrhachis, including chamber experiments for intraspecific and predator-prey trials. In particular, I will use these methods to investigate the relative roles of competition and predation as selection forces potentially driving spine evolution. This work will be conducted at the Xishuangbanna Tropical Botanical Gardens in Yunnan, China, with assistance from local collaborators.
Ants, Bison, and Fire on Konza Prairie
(Continuing work from senior thesis at University of Michigan)
(Image: Benjamin Blanchard)
Konza Prairie is a natural tallgrass prairie in northeastern Kansas, and also a Long Term Ecological Research (LTER) site. A large portion of the prairie has been divided into plots that vary in grazing (presence or absence of native bison) and burn regime (1-, 2-, 4-, or 20-year burn). This system is therefore ideal for studying influences of habitat heterogeneity on biological communities. In collaboration with Dr. Anthony Joern at KSU, I am investigating the impacts of bison grazing and fire frequency on ant species diversity and community composition, as well as compiling a species list for the prairie.