Research Interests

• Population-level genetic structure in threatened species
• Historical population structure (using museum DNA)
• Relationships between genetic variation and fitness in individuals
• Genetic aspects of behavioral ecology (inbreeding avoidance, extra-pair paternity)

Current Research

Inbreeding avoidance in red wolves

Kristin Brzeski, Ph.D. student (September 2010 - present)

Funding: School of Renewable Natural Resources
Collaborators: Mike Chamberlain (University of Georgia), David Rabon (Red Wolf Recovery Team)

Inbreeding and reduced genetic variation may depress health, reduce reproductive success, and decrease survivorship. These costs may drive species to evolve behavior to avoid kin as mates, a behavior that in small, inbred populations with limited mating opportunities could cause individuals to select mates from members of a closely related species. Kristin is undertaking research on endangered wild red wolves (Canis rufus) to examine whether inbreeding and low Mhc genetic variation decrease fitness; whether the fitness costs of inbreeding may cause red wolves to seek unrelated mates; and in cases where unrelated mates are not available, whether inbreeding avoidance causes red wolves to hybridize with coyotes. Kristin has access to long-term data collected by the red wolf Recovery Program for all wild red wolves (c. 250), which includes information on genealogical relationships, reproductive success and fitness, and blood samples. Her research will estimate the effect of inbreeding and genetic variation on red wolf fitness, examine a potential cause of hybridization with coyotes, and more generally provide a theoretical understanding of hybridization.

Genetic structure of Louisiana Bachman's Sparrows

Blain Cerame, M.Sc. student (September 2010 - present

Funding: Board of Regents Research Competitiveness Award
Collaborators: Robb Brumfield (Louisiana State University)

Bachman’s Sparrow (Peucaea aestivalis) is a species-at-risk that has declined from fire suppression, timber harvesting, and fragmentation of the open longleaf pine savannahs that it occupies. Information on genetic population structure in Bachman’s sparrows is unavailable but important for effective management at both broad and fine scales. Morphological data and distribution maps suggest that individuals east and west of the Mississippi River may represent separate evolutionarily significant units. At a finer scale, Bachman’s Sparrow habitat is fragmented. If individuals seldom disperse to isolated patches, inbreeding depression, population differentiation, and reduced genetic variation are likely to occur, potentially causing reductions in fitness. Blain will examine the genetic population structure of Bachman’s sparrows, including large-scale differences between populations east and west of the Mississippi, and the degree of gene flow, population structure and genetic variation among habitat fragments. The information that she collects will be helpful for managing habitat fragments to preserve reservoirs of genetic variation, and potentially for re-establishing gene flow in areas where it has been lost.

Mhc variation and mycoplasmal upper respiratory tract disease in Gopher Tortoises

Jean Elbers, PhD student (Sept 2011 – present)

Funding: Gilbert Fellowship
Collaborators: Rachel Wallace-Clostio (Louisiana State University)

The gopher tortoise, (Gopherus polyphemus), is a longleaf pine associated species that has experienced population declines and shows low levels of genetic diversity at microsatellite loci. Gopher tortoises are also susceptible to upper respiratory tract disease (URTD) caused by Mycoplasma agassizii, which may decrease population viability and increase extinction risk. Jean is investigating the relationship between functional genetic variation and disease resistance in the gopher tortoise (Gopherus polyphemus). He will quantify genetic variation in the major histocompatibility complex (Mhc), a genomic region in vertebrates that is closely related to disease resistance and immune response, and relate observed Mhc variation to disease susceptibility as well as habitat quality and characteristics to inform future management plans for gopher tortoises.

Seaside Sparrow response to the BP oil spill

Stefan Woltmann, Post-doctoral Fellow (June 2011 – present)

Funding: Gulf of Mexico Research Initiative RFP 1
Collaborators: Phil Stouffer (co-PI; LSU AgCenter), Linda Hooper-Bui (LSU AgCenter), LUMCON Consortium

The Deepwater Horizon oil spill released a large amount of crude oil into the Gulf of Mexico, an event that could have an important and negative impact on coastal ecosystems. Stef will focus on marsh bird populations, using the Seaside Sparrow (Ammodramus maritimus) as a model species to examine some potential effects of the oil spill. The Seaside Sparrow is an ideal marsh bird representative because it is endemic to salt marsh, it is sedentary (non-migratory) along the Gulf Coast, it is a top-level consumer in this ecosystem, and it is relatively abundant in the study area. He will examine whether exposure to oil affects adult survival and nest success, whether C14 levels indicative of crude oil are present in feathers and gut contents, and whether a gene that is active when exposed to PAHs is up-regulated in oiled areas. Population genetic approaches will be used to quantify Seaside Sparrow dispersal. This is important because the scale and degree of gene flow within the system determines re-colonization potential after population crashes caused by disasters such as the oil spill. Genetic analyses will clarify the degree of movement in and out of oiled areas, which will help to resolve whether birds transport oil or its byproducts through the ecosystem. The study area is nested within the ongoing sampling framework of our collaborators (LUMCON Consortium), and will include replication of unoiled and heavily oiled sites.

Loss of genetic variation in Arctic Peary caribou at Mhc and microsatellite loci

Funding: NSERC, School of Renewable Natural Resources
Collaborators: Peter Arcese (University of British Columbia), Debbie Jenkins (Government of Nunavut)

Genetic variation in wild populations is commonly estimated using neutral microsatellite loci even though it is functional genes that confer fitness and govern trait variation. If genetic variation at microsatellite loci provides an accurate estimate of genetic variation at functional loci, the choice of marker is inconsequential to questions about genetic diversity and fitness in wild populations. However, because neutral loci are only subject to genetic drift whereas functional loci are affected by drift and selection, the effect of population bottlenecks on genetic diversity at neutral and functional loci may differ. I am using historic and recent DNA samples from Peary caribou (Rangifer tarandus pearyi) to examine whether genetic variation is lost more quickly at microsatellite versus Mhc loci. A direct comparison of genetic variation over time at both types of marker will help to clarify whether selection may act to maintain variation at functional genes following a population bottleneck.

Mhc variation and malaria in Channel Island Song Sparrows

Funding: Board of Regents PFund
Collaborators: Peter Arcese (University of British Columbia), Rob Fleischer (Smithsonian Institution), Amy Wilson (Smithsonian Institution)

Channel Island Song Sparrows (Melospiza melodia) are susceptible to avian malaria. Together with my collaborators, I am using 454 next-generation sequence analysis to examine variation at Mhc genes to assess whether particular Mhc haplotypes and/or heterozygosity is related to malarial infection.