Detecting the True Extent of Introgression during Anthropogenic Hybridization. (April 2019)

• Record Type: Journal Article
• Authors: McFarlane, S. Eryn; Pemberton, Josephine M.
• Is Part Of: Trends in ecology & evolution. Volume 34:Number 4(2019)
• Page Start: 315
• Page End: 326
• Publication Date: 2019-04
• Subjects: Ecology -- Periodicals; Evolution (Biology) -- Periodicals; 576.8
• DOI: 10.1016/j.tree.2018.12.013
• Languages: English
• ISSNs: 0169-5347

Abstract

Abstract : Hybridization among naturally separate taxa is increasing owing to human impact, and can result in taxon loss. Previous classification of anthropogenic hybridization has largely ignored the case of bimodal hybrid zones, in which hybrids commonly mate with parental species, resulting in many backcrossed individuals with a small proportion of introgressed genome. Genetic markers can be used to detect such hybrids, but until recently too few markers have been used to detect the true extent of introgression. Recent studies of wolves and trout have employed thousands of markers to reveal previously undetectable backcrosses. This improved resolution will lead to increased detection of late-generation backcrosses, shed light on the consequences of anthropogenic hybridization, and pose new management issues for conservation scientists. Highlights: Anthropogenic hybridization is increasingly common and is likely to result in a breakdown of reproductive isolation between 'good' species. Backcrossed individuals that have only a small proportion of one parental genome are difficult to differentiate from parental individuals by using the most common current technologies. Bimodal hybrid zones are characterized by introgression and backcrossing. The majority of hybrid individuals in these systems have low levels of introgression. The problems posed by bimodal hybrid zones have been largely overlooked in the literature. Genome-wide sampling of genetic markers at high densities allow increased precision in the estimate of admixture proportions, which makes it feasible to detect multi-generation backcrosses, and will thus make it easier to differentiate bimodal hybrid zones from hybrid swarms or systems without introgression.