Introgression between Sphyrapicus nuchalis and S. varius sapsuckers in a hybrid zone in west‐central Alberta

Abstract

Studying species interactions at hybrid zones allows biologists to understand the forces that promote speciation. Hybridization among Sphyrapicus nuchalis, S. varius and S. ruber has long been acknowledged, and hybrid zones between S. nuchalis/S. ruber and S. varius/S. ruber have been characterized with both genetic and genomic data. Using a combination of next‐generation restriction site‐associated DNA sequencing (RAD‐Seq) and traditional genetic methods, we examined patterns of introgression in the poorly characterized S. nuchalis/S. varius contact zone; the two most similar species in the complex, though they are not each other's closest relatives. We found high introgression rates, with several early and many advanced generation hybrids along a 275 km stretch of Rocky Mountain foothill, pointing to a well‐established hybrid zone with hybrid individuals backcrossing with individuals from the parental species and each other. Plumage colouration in the hybrid zone was a relatively poor indicator of parental or hybrid status, which could be attributed to the possible involvement of few large effect genes.

Evidence for ancient selective sweeps followed by differentiation among three species ofSphyrapicussapsuckers

“…Moreover, these may be exacerbated by the disproportionate accumulation of sexually antagonistic sites on the Z chromosome, because selective sweeps in expression modifiers or preference alleles on the Z can accelerate differentiation in sexual traits and preferences between populations, therefore increasing behavioral incompatibilities and further deepening the divide between the species (Irwin 2018, Pryke et al 2010). Indeed, we see evidence that differentiation in sexual traits is associated with loci on the Z chromosome (E. Natola 2022).…”

“…Seventy-eight sapsucker samples were included in our WGS analysis: 10 allopatric individuals from each species, 15 hybrid zone individuals from each species cross, one putative 3-species hybrid, and two Williamson's Sapsuckers (Sphyrapicus thyroideus) included as outgroups (Figure 1). We selected hybrid zone individuals to represent a continuum of admixture proportions between each species pair based on ancestry coefficient values from prior GBS research (L. Natola et al 2021, 2022, Seneviratne et al 2016. Samples were tissues from vouchered museum specimens and blood from wild-caught birds collected by Sampath Seneviratne (Seneviratne et al 2012(Seneviratne et al , 2016 and included both male and female birds (Appendix C.1).…”

“…The copyright holder for this preprint this version posted March 25, 2023. ; https://doi.org/10.1101/2023.03.24.534187 doi: bioRxiv preprint 4 2018, Seneviratne et al 2012), CR (Natola & Burg 2018); a Z-linked locus CHD1Z (Natola & Burg 2018Seneviratne et al 2012; and Genotyping-by-Sequencing (GBS) of the nuclear genome (Curtis 2017, Grossen et al 2016, Natola et al 2021, Seneviratne et al 2016 all concur that the three forms are distinct based on genetic differentiation. Molecular dating based on mitochondrial DNA estimates that red-breasted and red-naped sapsuckers diverged 0.32 million years ago (MYA), and their common ancestor diverged from yellow-bellied sapsuckers approximately 1.09 MYA (Weir & Schluter 2004), time frames over which there have been many cycles of glacial and interglacial periods (Menounos et al 2009).…”

When One’s Not Enough: Colony Pool-Seq Outperforms Individual-Based Methods for Assessing Introgression in Apis mellifera mellifera

“…Alongside the choice of how to best sample a colony, the choice of genotyping approach is also important. Common genotyping methods for studying introgression are mitochondrial sequencing [ 43 , 44 ], microsatellite analysis [ 45 , 46 ], restriction site-associated DNA sequencing (RAD-seq) [ 47 , 48 ], and whole genome sequencing (WGS) [ 49 , 50 ]. Single nucleotide polymorphism (SNP) information has been demonstrated to outperform other methods for estimating honey bee introgression [ 32 , 51 ].…”

Phylogeographic structure of Heteroplexis (Asteraceae), an endangered endemic genus in the limestone karst regions of southern China

“…In particular, restriction site-associated DNA sequencing (RADseq), which is of low cost and does not require reference genomic information to obtain a large number of genome-wide markers, has been increasingly used in phylogeographic studies ( Baird et al., 2008 ; Brandrud et al., 2020 ; Spriggs and Fertakos, 2021 ). For example, RADseq has been used to resolve complex phylogenetic relationships and species boundaries ( Rubin et al., 2012 ; Ferrer Obiol et al., 2021 ; Ye et al., 2021 ), assess genetic diversity and structure ( Cai et al., 2020 ), and infer interspecific gene flow ( Natola et al., 2021 ) and demographic history ( Hellwig et al., 2020 ; Tao et al., 2021 ). The obtained genetic information is valuable for studying species differentiation and evolutionary history.…”