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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED MANAGEMENT OF IMPORTED FIRE ANTS AND EMERGING URBAN PEST PROBLEMS

Location: Imported Fire Ant and Household Insects

Title: Ecological metrics predict connectivity better than geographic distance

Authors
item Hokit, Grant -
item Ascunce, Marina
item Ernst, Joel -
item Branch, Lyn -
item Clark, Annmarie -

Submitted to: Conservation Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 3, 2009
Publication Date: November 25, 2009
Citation: Hokit, G., Ascunce, M.S., Ernst, J., Branch, L., Clark, A. 2009. Landscape Characteristics influence spatial genetic variation of the Florida scrub lizard (Sceloporus woodi). Conservation Genetics. 11(1):149-159.

Interpretive Summary: Florida Scrub Lizard (Sceloporus woodi) is a well-studied endemic organism of Florida that has been classified as threatened. Because scrub lizards are habitat specialists that live in dry upland such as sand pine scrub, oak scrub and sand hill, the primary conservation concern is loss of habitat. They require sunny areas with large amounts of bare sand, such as habitats that have been kept open by fire. Loss of habitat has caused a decline in scrub lizard populations and increase isolation of remaining populations. The small patches of lizard habitat have become more isolated because of human development and fire suppression leading to loss of connectivity among patches. Understanding how landscape structure and processes affect gene flow is crucial to improving conservation strategies. Landscape characteristics such as habitat patch size, isolation, and the type and quality of habitat matrix, interact with the dispersal ability of species to affect evolutionary and ecological processes. In this study, scientists at Carroll College, the University of Forida and the Center for Medical, Agricultural, and Veterinary Entomology, USDA-ARS, Gainesville, Florida, use genetic markers (microsatellite data) to assess population structures in the Florida scrub lizard at the finer scale of neighboring scrub patches. We found that that pairwise isolation (a metric used in ecological studies that includes patch size, quality and a modified isolation index) was a better predictor of genetic distance than Euclidean distance, indicating that mesic and hydric habitat influence spatial patterns in genetic variation of the scrub lizard. This is an interesting conclusion, since this parameter is commonly used in ecological studies and never before used in a landscape genetics context. Further landscape genetic studies of Florida habitat specialist organisms can provide insights to guide conservation decisions and management of natural areas.

Technical Abstract: We use microsatellite loci to examine genetic structure of the Florida scrub lizard (Sceloporus woodi) and test for the influence of landscape variables at the scale of neighboring patches. We also evaluate ecological metrics of connectivity with genetics data. Florida scrub is a highly threatened ecosystem in which habitat patches are remnants of a previously widespread xeric landscape. Analysis of mitochondrial DNA (mtDNA) has shown that landscape structure influenced the evolutionary history of the Florida scrub lizard (Sceloporus woodi) across its range. Our results concur with these mtDNA studies in documenting divergence between xeric ridge systems and also demonstrate divergence at very local scales. Both least-cost distance and pairwise isolation (a metric used in ecological studies that includes patch size, quality and a modified isolation index) were better predictors of genetic distance than Euclidean distance, indicating that mesic and hydric habitat influence spatial patterns in genetic variation. Our results support the need for focusing on spatial distribution of scrub habitat at the scale of neighboring patches, as well as regionally, in conservation management and restoration. Also, our study points to the value of integrating landscape ecology metrics into landscape genetics.

Last Modified: 4/19/2014
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