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Brent Brookes

Student Speaker | Étudiant.e
Understanding the drivers of successful species invasions is important for conserving native biodiversity and for mitigating the economic impacts of introduced species. However , whole genome resolution investigations of the underlying contributions of neutral and adaptive genetic variation to successful colonization in introduced populations are rare. Increased propagule pressure should result in greater neutral genetic variation, while environmental differences should elicit selective pressures on introduced populations, potentially supporting greater adaptive genetic variation. We investigated neutral and adaptive variation among nine introduced brook trout (Salvelinus fontinalis) populations using whole-genome pooled sequencing (28,490,618 SNPs). The populations inhabit isolated alpine lakes in western Canada and descend from a common source, with an average of ~19 (range of 7-41) generations since introduction. We found some evidence of bottlenecks, no strong evidence of purifying selection, and little support that varying propagule pressure or differences in local environments shaped observed neutral genetic variation differences. Putative outlier analysis revealed non-convergent patterns of adaptive differentiation among lakes with minimal outlier loci (0.001%-0.15%) that did not correspond with tested environmental variables . Our results suggest that (i) introduction success is not always strongly influenced by genetic load, (ii) observed differentiation among introduced populations can be idiosyncratic, population-specific, or stochastic, and (iii) conservatively, in some introduced species, colonization barriers may be overcome by a single footing in propagule pressure or benign environmental conditions coupled with plasticity.