Molecular Markers Reveal Limited Population Genetic Structure in a North American Corvid, Clark’s Nutcracker (Nucifraga columbiana)

Abstract

The genetic impact of barriers and Pleistocene glaciations on high latitude resident species has not been widely investigated. The Clark’s nutcracker is an endemic North American corvid closely associated with Pinus-dominated forests. The nutcracker’s encompasses known barriers to dispersal for other species, and glaciated and unglaciated areas. Clark’s nutcrackers also irruptively disperse long distances in search of pine seed crops, creating the potential for gene flow among populations. Using the highly variable mitochondrial DNA control region, seven microsatellite loci, and species distribution modeling, we examined the effects of glaciations and dispersal barriers on population genetic patterns and population structure of nutcrackers. We sequenced 900 bp of mitochondrial control region for 169 individuals from 15 populations and analysed seven polymorphic microsatellite loci for 13 populations across the Clark’s nutcracker range. We used species distribution modeling and a range of phylogeographic analyses to examine evolutionary history. Clark’s nutcracker populations are not highly differentiated throughout their range, suggesting high levels of gene flow among populations, though we did find some evidence of isolation by distance and peripheral isolation. Our analyses suggested expansion from a single refugium after the last glacial maximum, but patterns of genetic diversity and paleodistribution modeling of suitable habitat were inconclusive as to the location of this refugium. Potential barriers to dispersal (e.g. mountain ranges) do not appear to restrict gene flow in Clark’s nutcracker, and postglacial expansion likely occurred quickly from a single refugium located south of the ice sheets.

Phylogeography, historical demography and habitat suitability modelling of freshwater fishes inhabiting seasonally fluctuating Mediterranean river systems: a case study using the Iberian cyprinid Squalius valentinus

“…A,B). These stellate networks are characteristic of populations in expansion, as we found in S. valentinus , and, as shown in other studies, sometimes of populations that do not have a significant genetic structure (Dohms & Burg ). Most Spanish Levantine rivers run for short distances before flowing into the Mediterranean Sea.…”

Extreme genetic structure in a social bird species despite high dispersal capacity

“…; Rutz et al . ; Dohms & Burg ). The recent coalescence of Iberian haplotypes, and the widespread distribution of ancestral haplotypes, indicates a young postglacial origin for the current genetic variation, coinciding with the concomitant role of the Iberian Peninsula as a major refugium for Palearctic vertebrates (Gómez & Lunt ; Ferrero et al .…”

How connectivity shapes genetic structure during range expansion: Insights from the Virginia's Warbler

“…For instance, Milá et al (2000) described similar mtDNA haplotype and nucleotide diversities for northern populations of MacGillivray's Warbler (Geothlypis tolmiei), concluding that postglacial expansion was responsible for the lack of variation and structure seen in that warbler. Similarly, in a recent study of Clark's Nutcrackers (Nucifraga columbiana), Dohms and Burg (2013) reported high levels of haplotype, nucleotide, and allelic diversity throughout much of the nutcracker's range, and attributed these findings and limited differentiation to population connectivity.…”