Sharlene E. Santana

OEB Ph.D.
B.S., Universidad de Los Andes, Merida, Venezuela
ssantana@bio.umass.edu

Please visit Sharlene Santana's new website

Research Interests

The long-term goal of my research is to gain insights into evolutionary patterns and processes in morphologically diverse groups, with a special emphasis on the ecomorphological mechanisms that can lead to such diversity. My dissertation research used Neotropical leaf-nosed bats (Family Phyllostomidae) as a model system to study these aspects. Phyllostomid bats present an outstanding diversity of diets and morphology, including species that specialize in eating insects, fruits, nectar, vertebrates, and blood. This variation makes phyllostomids an excellent group for studying how the evolution of different morphologies can lead to differences in performance, how performance can be modulated through behavior, and how these three factors can interact and result in dietary diversification.

Because of the potential complexity of their interactions, I used an integrated approach to address the relationship among morphology, performance and behavior in the dietary diversification of phyllostomid bats. As part of my dissertation, I studied whether variation in cranial morphology is related to variation in bite performance, measured as bite force. To address this question, I built a 3D bite force model that integrates data on cranial muscles and skull architecture with field-collected bite force data. This allowed me to investigate the mechanism of bite force production and its changes across different dietary habits. Bite force production could also vary within and among bat species due to changes in biting behavior during feeding. Therefore, another part of my dissertation investigated whether the ability to modulate bite force through changes in biting behavior evolved in tandem with dietary specialization.

Cranial morphology in phyllostomids exhibits variation that seems to correspond with diet, but teeth are the structures that contact food and therefore need to be taken into account as well. The third part of my dissertation focused on whether dental morphology is also associated with different diets and if it impacts feeding performance and behavior. This part is focused on the transition from insect to fruit feeding, a key step in the diversification of the family, and took into account other measures of performance (the ability to finely break insect exoskeleton) and behavior (chewing rates).

Finally, although the skulls of phyllostomids reflect specializations for feeding, mechanical optimization may have also evolved for other behaviors that contribute to fitness. A few species of phyllostomids utilize their teeth and jaws to excavate roosts in active termite nests, a behavior that is relevant to fitness. Using finite element analysis, I compared the performance of the skulls of roost-excavators and non-excavators while simulating excavation and feeding behaviors.