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Environment-dependent admixture dynamics in a tiger salamander hybrid zone
Benjamin M Fitzpatrick1, H Bradley Shaffer
1Center for Population Biology and Section of Evolution and Ecology, University of California, Davis, California 95616, USA. benfitz@ucdavis.edu
Evolution; International Journal of Organic Evolution
|July 23, 2004
Summary
Hybridization between barred and California tiger salamanders is influenced by pond type. Perennial ponds show higher nonnative gene flow, indicating complex genotype-by-environment interactions shape this hybrid zone.
Area of Science:
- Ecology
- Evolutionary Biology
- Genetics
Background:
- The barred tiger salamander (Ambystoma tigrinum mavortium) was introduced into the native range of the California tiger salamander (A. californiense).
- Hybridization between these two species has been ongoing for 50-60 years (15-30 generations) in central California.
Purpose of the Study:
- To investigate genetic and ecological factors influencing admixture between the two tiger salamander species.
- To analyze hybrid genotype frequencies across different breeding habitats.
Main Methods:
- Studied hybrid genotype frequencies in natural vernal pools, ephemeral cattle ponds, and perennial man-made ponds.
- Assessed linkage disequilibria between molecular markers.
- Examined deviations from Hardy-Weinberg equilibrium.
Main Results:
- Perennial ponds exhibited higher frequencies of nonnative alleles compared to seasonal ponds.
- The hybrid zone displayed a mosaic structure influenced by pond hydrology and ecology.
- Observed marker-specific deviations from Hardy-Weinberg equilibrium, suggesting genotype-by-environment interactions.
Conclusions:
- Pond type and associated ecological factors significantly influence salamander admixture.
- Complex genotype-by-environment interactions shape the ongoing hybridization and genetic structure of this hybrid zone.