Conservation Genetics

, Volume 10, Issue 5, pp 1281–1297 | Cite as

Delayed genetic effects of habitat fragmentation on the ecologically specialized Florida sand skink (Plestiodon reynoldsi)

  • Jonathan Q. RichmondEmail author
  • Duncan T. Reid
  • Kyle G. Ashton
  • Kelly R. Zamudio
Research Article


Populations rarely show immediate genetic responses to habitat fragmentation, even in taxa that possess suites of traits known to increase their vulnerability to extinction. Thus conservation geneticists must consider the time scale over which contemporary evolutionary processes operate to accurately portray the effects of habitat isolation. Here, we examine the genetic impacts of fragmentation on the Florida sand skink Plestiodon reynoldsi, a sand swimming lizard that is highly adapted to the upland scrub habitat of central Florida. We studied fragments located on the southern Lake Wales Ridge, where human activity in the latter half of the 20th century has modified the natural patchiness of the landscape. Based on a relaxed molecular clock method, we estimate that sand skinks have persisted in this region for approximately 1.5 million years and that the time frame of human disturbance is equivalent to fewer than 30 skink generations. Using genotypes from eight microsatellite loci, we screened for molecular signatures of this disturbance by assessing congruence between population structure, as inferred from spatially-informed Bayesian assignment tests, and the current geography of scrub fragments. We also tested for potential intrapopulation genetic effects of inbreeding in isolated populations by comparing the average pairwise relatedness of individuals within fragments of different areas and isolation. Our results indicate that although some patches show a higher degree of relatedness than expected under random mating, the genetic effects of recent isolation are not evident in this part of the species’ range. We argue that this result is an artefact of a time-lag in the response to disturbance, and that species-typical demographic features may explain the genetic inertia observed in these populations.


Habitat fragmentation Skink Ecological specialization Genetic inertia Plestiodon reynoldsi 



We thank A. Knipps, B. Branciforte, B. Meneken, J. Zipser, and volunteers from the Earthwatch Institute for help with fieldwork, S. Bogdanowicz for help with microsatellite development, and R. Pickert for assistance with GIS landscape modelling. H. Mushinsky provided constructive comments on the manuscript. We also thank H. Swain for providing support with field efforts and landscape modelling at the Archbold Biological Station. O. François provided valuable advice concerning the HMRF models. R. Bukowski facilitated the use of computer resources at the Computational Biology Service Unit (Cornell University) that receives partial funding from Microsoft. This study was funded by research grants from: Archbold Biological Station, the Florida Fish and Wildlife Conservation Commission, and the Earthwatch Institute (KGA); the Cornell Hughes Scholars Program, Sigma Xi Grants in Aid of Research, Einhorn Discovery Grant, and the Cornell Undergraduate Board (DTR); and the National Science Foundation (DEB 9907798) and Cornell College of Arts and Sciences (KZ).


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Jonathan Q. Richmond
    • 1
    Email author
  • Duncan T. Reid
    • 1
    • 2
  • Kyle G. Ashton
    • 3
  • Kelly R. Zamudio
    • 1
  1. 1.Department of Ecology and Evolutionary BiologyCornell UniversityIthacaUSA
  2. 2.National Institutes of HealthBethesdaUSA
  3. 3.Archbold Biological StationLake PlacidUSA

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