EcoEvoPub Series

Department of Ecology and Evolutionary Biology Graduate Student Presentations

Thursday, November 15, 2012
5:00 PM
154 Biomedical Sciences Research Building

ADRIANA MALDONADO 
Department of Ecology and Evolutionary Biology
UCLA

“Plasticity responses of social network measures of yellow-bellied marmots (Marmota flaviventris)”

Abstract
Individuals in a population may adjust their phenotypic response to varying environmental conditions. Such plastic responses, that may affect population dynamics, often entail changes in an individual’s behavioral, morphological or physiological traits.  This variation may be an important source of variation in natural populations. Here we investigate the extent to which individuals in a population express plastic responses of behavioral traits to environmental variation in a yellow-bellied marmot (Marmota flaviventris) population. Our aim is to identify the proximate mechanism that shape the pattern of plasticity and how these mechanism respond to changes in different aspects of the biotic and abiotic environments. We constructed directed weighted networks for marmot social groups studied between 2002-2011.  We focused on affiliative behaviors (e.g., proximity, grooming, and greetings) and calculated embeddedness, a trait that has been shown to influence marmot dispersal. We analyzed social plasticity using a reaction norm approach. We fit a mixed-effect linear model to estimate parameters of the reaction norm as well as the between individual variation. Our results indicate that individuals express plasticity in embededdness in response to the social environment to which an individual is exposed, but embeddedness is not influenced by either environmental or physiological variables studied (spring temperature, body mass). Our findings suggest that the social environment plays a central role in plastically modifying embeddedness. Furthermore, since sociality affects reproductive traits such as the number of breeding females and the age of first reproduction, such behavioral variation may affect the population’s trajectory and its responses to environmental fluctuations.

EMILY CURD
Department of Ecology and Evolutionary Biology
UCLA

“A metagenomic study on the effects of vegetation type and soil depth on bacterial community structure”

Abstract
The soil is the largest terrestrial sink of carbon and it holds twice as much carbon as vegetation. Annual mineralization of this carbon into the atmosphere adds 10 times more CO2 than that derived from burning fossil fuels. Soil microbial communities are major contributors to soil carbon metabolism and thus control much of the CO2 flux between the soil and the atmosphere. We know little about the relative role of bacteria in soil carbon cycling or how that might be influenced by soil depth and vegetation.  To better understand whether vegetation C inputs into the soil affect microbial C storage and cycling, we are studying microbial communities within the same soil type and under three vegetation types with different C quality and quantities: grasslands, coastal sage scrub, and oak woodland.  I hypothesize that 1) vegetation types support unique soil microbial communities, and 2) microbial community structure and function will be distinct down the soil profile due to changes in C inputs. I will present preliminary data that suggests bacterial diversity and extracellular enzyme activity are affected by both vegetation type and soil depth. I will outline ongoing and future plans to investigate patterns of fungal diversity and the molecular mechanisms involved in carbon cycling.