Ecology and Evolutionary Biology

Ecology and Evolutionary Biology

Doctoral Program

Doctoral Program

EEB Proposal Defense – Mateo Garcia

Mateo Garcia (EEB student, Rosenthal Lab) will be defending his dissertation proposal Tuesday, March 19 and everyone is invited to attend the public portion of the proposal defense (info below).  His public presentation will be at 10 am in WFES 236.
His talk title is NATURAL HYBRIDIZATION AND MELANOMA IN SWORDTAIL FISH
Summary:  A growing literature has called attention to the importance of hybridization to the evolutionary process. When species hybridize, alleles that are benign in their specific genetic background can be deleterious or disadvantageous in the alternative background generating a variety of phenotypic consequences being cancer, more specifically melanoma,  one of them. Swordtails are the oldest animal model for the study of melanoma. Enforced hybridization under laboratory conditions has identified an epistatic interaction that affects pigmentation and can even induce melanoma development. X. birchmanni and X. malinche produce viable hybrids along several populations in the Sierra Madre (Hidalgo, Mexico) that present a macromelanophore pigment pattern called Spotted Caudal (Sc), which varies in its expression from a few black spots to extreme melanosis and eventually malignant melanoma. Combining population genomic studies in parental and hybrid populations we have identified a primary oncogene driving the expression of Sc as well as two tumor modifier candidate genes responsible for the switch from benign to malignant pigmentation. I am carrying out transgenic studies to characterize the modifying effect of these genes have on Sc-tumor development. Moreover, the frequency of Sc is significantly higher in males than in females suggesting that the expression of the phenotype might be affected by androgens. Testosterone treatments on females will inform us about relevant physiological and genetic interactions. Finally, higher Sc frequencies in juveniles compared to adults suggests that selection against Sc juveniles must be balanced by some source of positive selection on the phenotype in adults. The hypothesis that Sc may be under sexual selection either by female mate choice or male-male competition will be tested by several behavioral assays.

PI: Gil Rosenthal
Co-PI: Manfred Schartl
Committee: Kirk Winemiller, Heath Blackmon

Dissertation Defense – Zach Hancock

Zach Hancock (EEB student, Wicksten Lab) will be defending his dissertation proposal next Friday and everyone is invited to attend the public portion of the defense (flyer attached).  His public presentation is Dec 14 at 1:00 pm in WFES 411.
His talk title is On the Origin of Haustoriid Species: Phylogenetics and speciation of sand-burrowing amphipods
Summary: Understanding the formation of new species is of critical importance to taxonomy, which has been aided in recent decades by the widespread incorporation of molecular techniques. This is particularly true when morphological divergence is limited (i.e., a cryptic species complex). Species delimitation, population genomics, and phylogenomics can help to resolve the mode of speciation in recently diverged taxa in concert with coalescent simulation modeling. This study aims at deciphering the origin of beach-burrowing crustaceans (Amphipoda: Haustoriidae), and will use each of these approaches in a step-wise manner to first generate a phylogeographic hypothesis, delimit potential cryptic lineages, test for introgression and hybridization, and finally examine trait evolution at the family level.

Spotlight: Janelle Goeke

Janelle Goeke is a PhD student interested in coastal ecology.  She received her BS from the State University of New York at Geneseo.

Janelle will be studying community shifts due to mangrove encroachment into salt marshes along the Gulf coast.  She is particularly interested in the changes in food web interactions as a result of the mangrove encroachment.