Phylogeography of a migratory songbird across its Canadian breeding range: Implications for conservation units

Abstract

The objectives of this study were to describe and evaluate potential drivers of genetic structure in Canadian breeding populations of the Ovenbird, Seiurus aurocapilla. We performed genetic analyses on feather samples of individuals from six study sites using nuclear microsatellites. We also assessed species identity and population genetic structure of quill mites (Acariformes, Syringophilidae). For male Ovenbirds breeding in three study sites, we collected light‐level geolocator data to document migratory paths and identify the wintering grounds. We also generated paleohindcast projections from bioclimatic models of Ovenbird distribution to identify potential refugia during the last glacial maximum (LGM, 21,000 years before present) as a factor explaining population genetic structure. Birds breeding in the Cypress Hills (Alberta/Saskatchewan) may be considered a distinct genetic unit, but there was no evidence for genetic differentiation among any other populations. We found relatively strong migratory connectivity in both western and eastern populations, but some evidence of mixing among populations on the wintering grounds. There was also little genetic variation among syringophilid mites from the different Ovenbird populations. These results are consistent with paleohindcast distribution predictions derived from two different global climate models indicating a continuous single LGM refugium, with the possibility of two refugia. Our results suggest that Ovenbird populations breeding in boreal and hemiboreal regions are panmictic, whereas the population breeding in Cypress Hills should be considered a distinct management unit.

The strength of migratory connectivity for birds en route to breeding through the Gulf of Mexico

“…Surprisingly, we did not find a carry-over effect of winter habitat on migration timing for American redstarts, a relationship that has support for winter departure and breeding arrival (Marra et al 1998, Tonra et al 2011, Cooper et al 2015. eastern breeding ovenbirds migrating through eastern Florida; Haché et al 2017) or pass over coastal areas and stopover further inland (Buler et al 2017, Gómez et al 2017. Carry-over effects from winter habitat on migration timing may be both species-and population-specific and best measured throughout the annual cycle (Briedis et al 2018) and migration routes across a region.…”

“…For example, it is possible that we missed breeding populations that do not migrate through the GOM region (e.g. eastern breeding ovenbirds migrating through eastern Florida; Haché et al 2017) or pass over coastal areas and stopover further inland (Buler et al 2017, Gómez et al 2017. Comparison among populations along all possible migration routes would not be trivial to accomplish but is likely to elucidate further patterns to the strength of migratory connectivity, including carry-over from winter.…”

“…For all three of these species, western breeding populations predominately winter further west in Central America and Mexico while central and eastern breeding populations predominately winter in the Caribbean (American redstart and ovenbird) or further east in Central America (wood thrush) (Norris et al 2006, Rushing et al 2014, Stanley et al 2015, Haché et al 2017. For all three of these species, western breeding populations predominately winter further west in Central America and Mexico while central and eastern breeding populations predominately winter in the Caribbean (American redstart and ovenbird) or further east in Central America (wood thrush) (Norris et al 2006, Rushing et al 2014, Stanley et al 2015, Haché et al 2017.…”

“…Migratory connectivity for American redstart, ovenbird, and wood thrush are among the best understood of Nearctic-Neotropical bird species. For all three of these species, western breeding populations predominately winter further west in Central America and Mexico while central and eastern breeding populations predominately winter in the Caribbean (American redstart and ovenbird) or further east in Central America (wood thrush) (Norris et al 2006, Rushing et al 2014, Stanley et al 2015, Haché et al 2017. Based on the strength of migratory connectivity between breeding and wintering areas (Hallworth and Marra 2015, Stanley et al 2015, Cohen et al 2018, we expected en route migratory connectivity to be weaker for wood thrush than for American redstart and ovenbird.…”

The contribution of genetics and genomics to understanding the ecology of the mountain pine beetle system

“…Phylogeographic insights provide information on historical demographic and geographic patterns, allowing some evolutionary mechanisms to be inferred. Such studies have been used to identify source populations of invasive species (e.g., Kerdelhué et al 2014), delineate conservation management areas (e.g., Haché et al 2017), and predict range limits (e.g., Winkler et al 2012); however, the application of phylogeographic studies in irruptive forest insect species has been questioned. This is primarily because fundamental niche spaces may be obscured by low within-species signatures of genetic diversity as a result of constant population growth and decline (Godefroid et al 2016).…”