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Multiple sources, admixture, and genetic variation in introduced anolis lizard populations
Jason J Kolbe1, Richard E Glor, Lourdes Rodríguez Schettino
1Department of Biology, Campus Box 1137, Washington University, St. Louis, MO 63130, USA. kolbe@berkeley.edu
Summary
Invasive species often have high genetic variation due to admixture from multiple native sources, challenging the idea of founder effects limiting alien species. This genetic diversity aids their establishment and spread.
Area of Science:
- Ecology and Evolutionary Biology
- Genetics and Genomics
- Invasive Species Research
Background:
- Classical theory posits invasive species have reduced genetic variation due to founder effects and bottlenecks.
- This genetic impoverishment is thought to hinder invasive species' establishment, spread, and adaptation.
- Recent studies challenge this, revealing higher-than-expected genetic variation and rapid evolution in introduced populations.
Purpose of the Study:
- To investigate the genetic variation and origins of introduced Anolis lizard populations.
- To test whether multiple native-range sources and admixture explain observed genetic patterns in invasive species.
- To compare genetic variation in introduced populations with their native-range counterparts.
Main Methods:
- Analysis of mitochondrial DNA (mtDNA) sequence data from 10 Anolis lizard introductions across 8 species.
- Examination of genetic variation and haplotype distribution in both native and introduced populations.
- Comparison of genetic divergence and admixture levels between native and introduced populations.
Main Results:
- Eighty percent of introductions involved multiple native-range source populations.
- Two-thirds of introduced populations showed evidence of admixture from two or more sources.
- Introduced populations exhibited nearly double the genetic variation (mean pairwise sequence divergence 2.6%) compared to native populations (1.4%).
Conclusions:
- Admixture from multiple native sources significantly increases genetic variation in introduced populations, contradicting classical theories.
- This elevated genetic diversity, facilitated by admixture, is a key factor in the successful establishment and spread of invasive species.
- A two-step introduction process is proposed: initial reduction via founder effects, followed by increase through admixture.
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