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Hybrid vigor between native and introduced salamanders raises new challenges for conservation
Benjamin M Fitzpatrick1, H Bradley Shaffer
1Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA. benfitz@utk.edu
Summary
Hybridization between native California Tiger Salamanders and introduced Barred Tiger Salamanders results in hybrid vigor, boosting offspring survival rates. This hybrid vigor, driven by genetic mechanisms, may enhance admixed populations despite complicating conservation efforts.
Area of Science:
- Evolutionary biology
- Conservation genetics
- Ecology
Background:
- Hybridization between native and introduced species presents complex conservation challenges.
- Understanding fitness consequences of hybridization is crucial for predicting evolutionary outcomes.
- Native California Tiger Salamanders (Ambystoma californiense) are hybridizing with introduced Barred Tiger Salamanders (Ambystoma tigrinum mavortium).
Purpose of the Study:
- To measure natural selection on hybrid larvae in wild populations.
- To determine the fitness consequences of hybridization between native and introduced tiger salamanders.
- To investigate the genetic mechanisms underlying hybrid vigor.
Main Methods:
- Studied differential viability of hybrid larvae in natural populations.
- Analyzed survival rates of mixed-ancestry genotypes compared to pure native or introduced genotypes.
- Employed statistical methods to support overdominant and recombinant contributions to hybrid vigor.
Main Results:
- Strong evidence of hybrid vigor observed, with mixed-ancestry genotypes exhibiting higher survival rates.
- Both overdominance and recombinant hybrid vigor contribute to enhanced fitness in larval tiger salamanders.
- Recombinant homozygous genotypes with mosaic ancestry show potential to become established.
Conclusions:
- Hybrid vigor enhances survival and population viability in admixed tiger salamander populations.
- The persistence of genetically pure native populations may be threatened by successful hybridization.
- Conservation and management strategies must consider the complex evolutionary dynamics and potential fitness benefits of hybridization.
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