May 19 2009

12:00 154 BSRB

EcoLunch Series

Graduate Student Presentations by Marisa Tellez, Princess Gilbert and Chris Creese


Marisa Tellez
"When the Predator becomes the Prey: Investigating the parasitism of hybrids between Crocodylus acutus and Crocodylus moreletii, and gene flow patterns of a crocodilian parasite"

Hybridization has proven to be unpredictable when analyzing its impact on host parasitism, but additional studies can provide greater insight to the limits of host-parasite specificity, host susceptibility, and the dynamic role parasites play in host populations. My proposed research will investigate parasitism in hybrids of the American Crocodile (Crocodylus acutus) and the Morelets Crocodile (Crocodylus moreletii), examining how hybridization between these crocodilian species may have a benefit in combating parasitic infection. I will discuss the implications of possible results, and how the gene flow of a crocodilian parasite, Acanthostomum americanum may be affected. Acanthostomum americanum is known to infest three New World crocodilians at various locations around the Caribbean. Assessing the phylogeography of this parasite is necessary for understanding its adaptation capabilities and the evolution of host-parasite symbiosis. Furthermore, I will discuss how the assessment of gene flow of A. americanum can contribute in understanding host migration and the problematic phylogeny of New World crocodilians.

Princess Gilbert
"Diversification and Adaptive Variation in the Chameleons of Madagascar"

The island of Madagascar is treasured for its vast number of endemic species and its high level of biodiversity. It is home to almost half of all known chameleon species, including the largest, Furcifer oustaleti, and the smallest, Brookesia minima, in the world. Why is there so much diversity on this island and how has it been maintained? For my thesis, I will study diversification and adaptive variation in Furcifer oustaleti. I hope to find support for the hypothesis that habitat barriers have substantially reduced gene flow thereby causing genetic diversification. I have chosen to study the species Furcifer oustaleti because it is found throughout the island in at least 5 different biomes and I am primarily interested in the following questions: 1) Is there an association between a population's haplotype and its geographic location? 2) Do genetic differences between populations correlate with the environmental differences between each population's habitat? 3) Are there regions of Furcifer oustaletis genome under selection and are these loci the same for each population? To answer these questions I am utilizing phylogeography, environmental modeling and genomic analysis.

Chris Creese
Causes and Consequences of Variation in Fern Structure and Function

How is variation in fern leaf architecture adaptive to differences in environment? What are the mechanisms linking variation in fern morphology with physiology? Are ferns functionally primitive compared to angiosperms because of their ancient origins? The short answer is: We dont know! There are more assumptions about fern form and physiology than evidence. The goal of my dissertation research is to test these assumptions and provide a new framework for understanding fern ecophysiology and evolution. Currently, Im investigating: 1) adaptations to Mediterranean-type climate in Southern California ferns, and 2) broad patterns in Hawaiian fern morphology across species, growth forms, and habitats. For study 2, I created a Hawaiian pteridophyte trait database to test the hypothesis that differences in taxa distribution and abundance are linked to variation in frond morphology. Results demonstrate strong trait-trait and trait-environment relationships that help explain evolutionary patterns of Hawaiian fern diversity and biogeography.















































































































































































































































































































































































































































































































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