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High dispersal rates in hybrids drive expansion of maladaptive hybridization

November 9, 2022

Hybridization between native and invasive species, a major cause of biodiversity loss, can spread rapidly even when hybrids have reduced fitness. This paradox suggests that hybrids have greater dispersal rates than non-hybridized individuals, yet this mechanism has not been empirically tested in animal populations. Here, we test if non-native genetic introgression increases reproductive dispersal using a human-mediated hybrid zone between native cutthroat trout (Oncorhynchus clarkii) and invasive rainbow trout (Oncorhynchus mykiss) in a large and connected river system. We quantified the propensity for individuals to migrate from natal rearing habitats (migrate), reproduce in non-natal habitats (stray), and the joint probability of dispersal as a function of genetic ancestry. Hybrid trout with predominantly non-native rainbow trout ancestry were more likely to migrate as juveniles and to stray as adults. Overall, hybrids with greater than 50% rainbow trout ancestry were 5.7 times more likely to disperse than native or hybrid trout with small amounts of rainbow trout ancestry. Our results show a genetic basis for increased dispersal in hybrids that is likely contributing to the rapid expansion of invasive hybridization between these species. Management actions that decrease the probability of hybrid dispersal may mitigate the harmful effects of invasive hybridization on native biodiversity.

Publication Year 2022
Title High dispersal rates in hybrids drive expansion of maladaptive hybridization
DOI 10.1098/rspb.2022.1813
Authors Samuel Bourret, Ryan P. Kovach, Timothy Joseph Cline, Jeffrey Strait, Clint C. Muhlfeld
Publication Type Article
Publication Subtype Journal Article
Series Title Proceedings of the Royal Society B
Index ID 70241491
Record Source USGS Publications Warehouse
USGS Organization Northern Rocky Mountain Science Center