Historical processes and landscape context influence genetic structure in peripheral populations of the collared lizard (Crotaphytus collaris)
Populations at the periphery of a species’ range often show reduced genetic variability within populations and increased genetic divergence among populations compared to those at the core, but the mechanisms that give rise to this core-periphery pattern in genetic structure can be multifaceted. Peripheral population characteristics may be a product of historical processes, such as founder effects or population expansion, or due to the contemporary influence of landscape context on gene flow. We sampled collared lizards (Crotaphytus collaris) at four locations within the northern Flint Hills of Kansas, which is at the northern periphery of their range, to determine the genetic variability and extent of genetic divergence among populations for ten microsatellite loci (n = 229). We found low genetic variability (average allelic richness = 3.37 ± 0.23 SE; average heterozygosity = 0.54 ± 0.05 SE) and moderate population divergence (average FST = 0.08 ± 0.01 SE) among our sample sites relative to estimates reported in the literature at the core of the species’ range in Texas. We also identified differences in dispersal rates among sampling locations. Gene flow within the Flint Hills was thus greater than for other peripheral populations of collared lizards, such as the Missouri glade system where most of the mesic grasslands have been converted to forest since the last glacial retreat, which appears to have greatly impeded gene flow among populations. Our findings signify the importance of considering landscape context when evaluating core-peripheral trends in genetic diversity and population structure.
KeywordsMicrosatellites Flint Hills Tallgrass prairie Collared lizard
This project was supported by a grant awarded to K. A. With and S. M. Wisely by the Ecological Genomics Institute at Kansas State University, a University Small Research Grant awarded to K. A. With by Kansas State University, the Dean E. Metter Memorial Award from the Society for the Study of Amphibians and Reptiles awarded to E. Blevins, the Institute for Grassland Studies at Kansas State University, and the Konza Prairie NSF-LTER program. We thank the staff of Konza Prairie Biological Station for on-site assistance, E. Horne for project support and review of this manuscript, P. Klug for sample contributions and project assistance, the members of the Conservation Genetics and Molecular Ecology Lab at Kansas State University, and J. Whittier and A. Skibbe for technical assistance. We also thank members of the Kansas Herpetological Society and other volunteers who assisted with sample collection. Work was conducted in compliance with Kansas State University IACUC protocol #2297.
- Fitch H (1956) An ecological study of the collared lizard (Crotaphytus collaris). Univ Kansas Publ Mus Nat Hist 8:213–274Google Scholar
- Freeman CC (1998) The flora of Konza Prairie, a historical review and contemporary patterns. In: Knapp AK, Briggs JM, Hartnett DC, Collins SL (eds) Grassland dynamics: long-term ecological research in tallgrass prairie. Oxford University Press, New York, pp 69–80Google Scholar
- Gaston KJ (2003) The structure and dynamics of geographic ranges. Oxford University Press, OxfordGoogle Scholar
- Goudet J (1995) FSTAT (version 1.2): a computer program to calculate F-statistics. J Hered 86:485–486Google Scholar
- Hartnett DC, Fay PA (1998) Plant populations: patterns and processes. In: Knapp AK, Briggs JM, Hartnett DC, Collins SL (eds) Grassland dynamics: long-term ecological research in tallgrass prairie. Oxford University Press, New York, pp 81–100Google Scholar
- Keyghobadi N, Roland J, Matter SF, Strobeck C (2005) Among- and within-patch components of genetic diversity respond at different rates to habitat fragmentation: an empirical demonstration. Proc Natl Acad Sci USA 272:553–560Google Scholar
- McGuire JA (1996) Phylogenetic systematics of Crotaphytid lizards (Reptilia: Iguania: Crotaphytidae). Bull Carnegie Mus Nat Hist 32:1–143Google Scholar
- Raymond M, Rousset F (1995) GENEPOP (version 1.2): population genetics software for exact tests and ecumenicism. J Hered 86:248–249Google Scholar
- Reich DE, Feldman MW, Goldstein DB (1999) Statistical properties of two tests that use multilocus data sets to detect population expansions. Mol Biol Evol 16:453–466Google Scholar
- Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring HarborGoogle Scholar
- Whitaker AH (1996) Impact of agricultural development on grand skink (Oligosoma grande) (Reptilia: Scincidae) populations at Macraes Flat, Otago, New Zealand. Sci Conserv 33:1173–2946Google Scholar
- Yedlin IN, Ferguson GW (1973) Variations in aggressiveness of free-living male and female collared lizards, Crotaphytus collaris. Herpetologica 29:268–275Google Scholar