Invasive species are expected to experience a unique combination of high genetic drift due to demographic factors while also experiencing strong selective pressures. The paradigm that reduced genetic diversity should limit the evolutionary potential of invasive species and thus their potential for range expansion has received little empirical support, possibly due to the choice of genetic markers. Our goal was to test for effects of genetic drift and selection at functional genetic markers as they relate to the invasion success of two paired invasive goby species, one widespread (successful) and one with limited range expansion (less successful). We genotyped fish using two marker types: single nucleotide polymorphisms (SNPs) in known-function, protein-coding genes and microsatellites to contrast the effects of neutral genetic processes. We identified reduced allelic variation in the invaded range for the less-successful tubenose goby. SNPs putatively under selection were responsible for the observed differences in population structure between marker types for round goby (successful) but not tubenose goby (less successful). A higher proportion of functional loci experienced divergent selection for round goby, suggesting increased evolutionary potential in invaded ranges may be associated with round goby's greater invasion success. Genes involved in thermal tolerance were divergent for round goby populations but not tubenose goby, consistent with the hypothesis that invasion success for fish in temperate regions is influenced by capacity for thermal tolerance. Our results highlight the need to incorporate functional genetic markers in studies to better assess evolutionary potential for the improved conservation and management of species.
Usage Notes:
Goby_SNP_GTseq_genotyping
Script to map short reads to transcriptomic reference and call SNPs using GATK best practices workflow
RG_usat_data
Round goby microsatellite data in genepop format
RG_usat.gen
TNG_usat_data
Tubenose goby microsatellite data in genepop format
TNG_usat.gen
RG_SNP_data
Round goby SNP genotype data in genepop format
RG_SNP_genepop.gen
TNG_SNP_data
Tubenose goby SNP genotypes in genepop format
TNG_SNP_genepop.gen
GobySNP_main_analysis_script
R code for conducting all but the outlier analyses as described in the paper
GobySNP_main_analysis.R
GobySNP_outliers_script
R code for conducting FLK outlier analysis as described in the paper
GobySNP_outliers.R