Seminars

April 26 2012

5:00 pm 154 BSRB

EcoEvoPub Series

Graduate Student Presentations

Summary

HILTON OYAMAGUCHI
Department of Ecology and Evolutionary Biology
UCLA

“Evaluating the role of natural selection and genetic drift in the diversification process in frogs along the Brazilian rainforest-savanna gradient. ”

Although a growing number of studies have shown that ecological speciation may be common, previous work has largely used vicariant events to explain patterns of diversity in the Amazon rainforest. Evaluating the relative roles of genetic drift and divergent selection is fundamental to understanding the mechanisms of rainforest speciation, yet few studies have simultaneously examined these processes. My research investigates the relative roles of natural selection and genetic drift resulting in differentiation in the frog Dendropsophus minutus examining populations from the Amazon rainforest and the Brazilian savanna (Cerrado). Environmental differences between these habitats may result in contrasting selection pressures and may, as a consequence, be important in speciation. To understand the effects of divergent selection and genetic drift on intraspecific differentiation in D. minutus populations, I am analyzing morphometry, vocalization, and genetic data. In this study, I aim to demonstrate that the Amazon forest-Cerrado gradient plays an important role in the speciation process; and may have important implications for conservation decision makers in this region.

RODRIGO MENDEZ ALONZO
Department of Ecology and Evolutionary Biology
UCLA

“Coordination Between Leaf and Stem Economics in a Tropical Dry Forest”

With data from 15 species in 8 families of tropical dry forest trees, we provide evidence of coordination between the stem and leaf economic spectra. Species with low density, flexible, breakable, hydraulically efficient but cavitationally vulnerable wood shed leaves rapidly in response to drought and had low leaf mass per area and dry mass content. In contrast, species with the opposite xylem syndrome shed their costlier but more drought resistant leaves late in the dry season. Our results explain variation in the timing of leaf shedding in tropical dry forests: selection eliminates combinations such as low productivity leaves atop highly vulnerable xylem or water-greedy leaves supplied by xylem of low conductive efficiency. Across biomes, rather than a fundamental trade-off underlying a single axis of trait covariation, the relationship between leaf and stem economics is likely to occupy a wide space in which multiple combinations are possible.

THURSDAY, APRIL 26, 2012
5PM IN 154 BIOMEDICAL SCIENCES RESEARCH BLDG

 

 

 

 

 

 



 

 

 

 

 

 

 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



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