Graduate STEM Fellow Profile

Danielle Trathen

Project Title: IMPACT LA: Improving Minority Partnerships and Access through CISE-related Teaching
Thesis: Comparative phylogeography of Caribbean sea slugs with long-lived vs. short-lived larvae
College/University: California State University, Los Angeles
Research Advisor: Dr. Patrick Krug
Degree Sought: Masters in Biology
Department: Biology Lab
Research Focus: Ecology and evolution of sea slugs.
Teaching Partner(s): Laura Ruiz

Description of Research

Predicting patterns of gene flow is important for conservation and management of marine animal populations. Biophysical coupling models have been developed for the Caribbean that use ocean currents and the lifespan of planktonic larvae to predict whether populations will be genetically connected or isolated. To test model predictions, we determined population genetic structure for the sea slugs Elysia patina and E. zuleicae which have a 30-day planktonic larval period. A portion of the mitochondrial cytochrome c oxidase I gene was sequenced for samples from 13 Caribbean locations. Phylogenetically distinct clades were identified by Bayesian Inference, and Analysis of Molecular Variance (AMOVA) was used to determine realized gene flow among islands. Despite its considerable potential for larval dispersal, Elysia patina had surprisingly high population structure; clades were up to 10% divergent, and several were restricted to one island. In contrast, the co-occurring E. zuleicae had little structure, but also comprised two major clades that were 10% divergent. In contrast to published predictions from oceanographic models, there was no east-west break across the Caribbean, but there were deep barriers to gene flow among neighboring islands in the Bahamas. Larval life span is thus a poor predictor of realized dispersal, and current models do not accurately predict larval exchange for common Caribbean mollusks. Differences in larval behavior may explain why less migration has occurred among populations of E. patina on historical and recent time scales, compared to other Elysia spp.

Example of how my research is integrated into my GK-12 experience

I have done several activities to incorporate my research into the classroom. One activity had the students design a marine protected areas (MPAs). Improving MPAs is one of the incentives for doing my research. I did this activity in the beginning of the school year to give a simple introduction to my research and the implications of the research that I do. This activity incorporated three of the concepts that my class was focusing on at that time food chains, animal behavior and the keystone predator hypothesis. I gave a power point presentation that gave the students all of the information they need to know about the animals; where they live, what they eat and what happens if they disappear or have a population expansion. The power point presentation also defined terminology they needed to know, such as marine protected area, keystone predator hypothesis and biodiversity. In the activity sea otters in Alaska represented the keystone species. When otters were hunted sea urchin population expanded, kelp forests were depleted by all of the urchins and over all biodiversity was decreased due to lack of food and shelter. Students represented one of three industries fur, fishery or ecology. Based on the best interest of their industry students had to develop a MPA that would revitalize it. In the end students realized that each animals was important and needed to be protected for their industry to thirve based their knowledge of food chains and keystone predators.