Introgression between invasive and native blue mussels (genus Mytilus) in the central California hybrid zone. Issue 18 (3rd September 2015)

• Record Type: Journal Article
• Authors: Saarman, Norah P.; Pogson, Grant H.
• Is Part Of: Molecular ecology. Volume 24:Issue 18(2015)
• Page Start: 4723
• Page End: 4738
• Publication Date: 2015-09-03
• Subjects: Molecular ecology -- Periodicals; Molecular population biology -- Periodicals; 576
• DOI: 10.1111/mec.13340
• Languages: English
• ISSNs: 0962-1083

Abstract

<abstract abstract-type="main" id="mec13340-abs-0001"> <title>Abstract</title> <p>The ecological and genetic factors determining the extent of introgression between species in secondary contact zones remain poorly understood. Here, we investigate the relative importance of isolating barriers and the demographic expansion of invasive <italic>Mytilus galloprovincialis</italic> on the magnitude and the direction of introgression with the native <italic>Mytilus trossulus</italic> in a hybrid zone in central California. We use double‐digest restriction‐site‐associated DNA sequencing (ddRADseq) to genotype 1337 randomly selected single nucleotide polymorphisms and accurately distinguish early and advanced generation hybrids for the first time in the central California <italic>Mytilus</italic> spp. hybrid zone. Weak levels of introgression were observed in both directions but were slightly more prevalent from the native <italic>M. trossulus</italic> into the invasive <italic>M. galloprovincialis</italic>. Few early and advanced backcrossed individuals were observed across the hybrid zone confirming the presence of strong barriers to interbreeding. Heterogeneous patterns of admixture across the zone of contact were consistent with the colonization history of <italic>M. galloprovincialis</italic> with more extensive introgression in northern localities furthest away from the putative site of introduction in southern California. These observations reinforce the importance of dynamic spatial and demographic expansions in determining patterns of introgression between close congeners, even in those with high dispersal potential and well‐developed reproductive barriers. Our results suggest that the threat posed by invasive <italic>M. galloprovincialis</italic> is more ecological than genetic as it has displaced, and continues to displace the native <italic>M. trossulus</italic> from much of central and southern California.</p> </abstract>