STRI Short Term Fellow and doctoral student at PSU
Alexis’ Personal webpage
I am a Biology Ph.D. graduate student in George (PJ) Perry’s Anthropological Genomics Lab at Penn State University. My dissertation research is focused on integrating morphological and evolutionary genomics techniques to characterize how human behavior impacts non-human evolutionary biology.
I am working with Aaron at STRI to collect modern, archaeological, and paleontological shell materials from Bocas del Toro. Strombus pugilis is a species of conch that has decreased in body size at maturity over the past ~7000 years possibly due to size-selective human subsistence pressures. I’ll export these shell samples, along with some modern tissue samples, back to PSU and attempt to extract and sequence both modern and ancient DNA from these materials.
One long-term goal is to perform a genome-wide association study (GWAS) to identify genetic loci associated with body size variation in these marine snails. These loci could then be studied with evolutionary population genomic methods to test the hypothesis that small body size has evolved via a history of positive natural selection. If ancient DNA can be extracted and sequenced from the archaeo- and paleontological sites, it will be possible to directly track the evolutionary history of size-associated genetic variants over time, relative to genetic variants from other regions of the genome.
Intern (SENACYT, STRI, University of Panama)
I’m a Biology undergraduate student at University of Panama profoundly interested in Marine Biology and paleontology, especially the evolution, adaptation and ecology of coral reefs. I’m working on a project that consists of reconstructing the Caribbean reef fish communities of the past, and my master tools for this research are fish otoliths. Otoliths have distinct shapes that enable us to identify fish families, sometimes even to the level of species and fossil otoliths may help us reconstruct the reef fish community of the Caribbean 7000 years ago (i.e. before human impacts). This information will provide a baseline that will enable us to compare “pristine” with modern reef fish communities.
STRI Pre-doc fellow
Abby is working on a project that explores how marine life, specifically molluscs, respond to the differing energy regimes of the Pacific and Caribbean sides of the Isthmus of Panama. The Pacific experiences coastal upwelling and high nutrient availability, corresponding to high productivity, while the Caribbean experiences no upwelling and low productivity. How do marine communities, which share many of the same species, differ between the Caribbean and Pacific sides?
PhD Student UC Santa Barbara and STRI Fellow
Reconstructing shark communities using dermal denticles preserved in reef sediments
What were shark communities like before humans? Ecological surveys and historical records demonstrate significant declines in Caribbean shark populations, yet pre-exploitation baselines are nonexistent. Dermal denticles – tiny, tooth-like scales lining the skin of elasmobranchs – can offer insight into shark communities on reefs. We have found denticles to be beautifully preserved in fossil and modern reef sediments, allowing morphometric analysis and classification. Denticle traits are also closely associated with shark ecology and can paint a picture of shark community composition. Evaluating the relative abundances of different denticle morphotypes in sediment samples across time and space can both supplement existing survey data – using time-averaged modern sediments – and assist in the reconstruction of pre-human shark baselines – using the recent fossil record. This previously unexplored data source may reveal what shark communities looked like prior to the advent of fishing, facilitating exciting and important assessments of the magnitude and ecological consequences of global shark declines and producing more meaningful conservation targets.
Save our seas ~ Erin’s Website