EcoEvoPub Series

Presented by UCLA's Department of Ecology and Evolutionary Biology

Thursday, October 03, 2013
5:00 PM
154 BIOMEDICAL SCIENCES RESEARCH BLDG

LAUREL SERIEYS
Department of Ecology and Evolutionary Biology
UCLA

“Disease and freeways drive temporal and spatial genetic changes among bobcat subpopulations in an urban, fragmented landscape”

Urbanization profoundly impacts animal populations by causing isolation, increased susceptibility to disease, and exposure to toxicants. Genetic effects of isolation can include reduced effective population size, increased population substructure, and decreased adaptive potential. Although the consequences of urbanization are increasingly well known, to my knowledge, no previous studies have examined how urbanization influences genetic variation at both neutral and functional loci. I hypothesized that urbanization and disease shape genetic diversity in bobcats (Lynx rufus) across an urban landscape, and that disease enhances selection on immune genes. I examined a bobcat population distributed across a highly fragmented, urban landscape in California. More than 300 bobcats, sampled from 1996-2012, were genotyped for variation at nine neutral microsatellite loci and seven microsatellite loci linked to regions involved in innate (toll-like receptor) and adaptive (major histocompatibility complex) immunity. Two different freeways were significant barriers to gene flow. Further, a 3-year disease epizootic (associated with secondary rodenticide exposure) caused a population bottleneck that led to significant genetic differentiation pre- and post-disease that was greater than for subpopulations separated by major freeways for > 60 years. However, balancing selection acted on immune loci during the epizootic and maintained variation. These data indicate that in urban landscapes, balancing selection can regulate patterns of genetic variation at immune-linked loci despite the effects of extreme drift that drives genetic diversity loss and population substructure at neutral loci. Studies aimed solely at neutral variation as proxies for the effects of drift will miss functional variation retained by natural selection. Conservation assessments need to include diverse loci that are potentially under selection in order to better preserve the adaptive potential of populations at the urban-wildland interface. Further, even for highly mobile species, freeways and disease can be principle causes of population structure in urban landscapes.

MAGGIE SIMON
Department of Ecology and Evolutionary Biology
UCLA

“The Effect of Biotic and Abiotic Factors on Agricultural Pest Invasion”

Species invasions constitute one of the major anthropogenic perturbations of natural and agricultural systems.  Successful establishment and spread of exotic, invasive species requires that both abiotic and biotic aspects of the new habitat be conducive to their population growth. Successful invasives are typically species with a broad tolerance for their new abiotic environment, and those that are either released from natural enemies in their new habitat or are stronger resource competitors than their native counterparts.  I present an ongoing study in which I examine the interplay between biotic (competition) and abiotic (temperature) factors and their effects on the establishment of an agricultural insect pest, the bagrada bug (Bagrada hilaris), in regions shared with a native resource competitor, the harlequin bug (Murgantia histrionica).  I combine trait-based temperature-response experiments in the lab with mathematical models to predict the outcomes of native-invasive competition under different temperature regimes.  I plan to test these predictions in the field using an experimental design that manipulates both temperature and species interactions (intra and inter-specific competition).  This study is part of a larger project aimed at understanding the mechanism by which biotic and abiotic factors influence the establishment and spread of agricultural pests in a naturally-occurring insect community.