Genomic divergence in allopatric Northern Cardinals of the North American warm deserts is linked to behavioral differentiation

Abstract

Biogeographic barriers are considered important in initiating speciation through geographic isolation, but they rarely indiscriminately and completely reduce gene flow across entire communities. Explicitly demonstrating which factors are associated with gene‐flow levels across barriers would help elucidate how speciation is initiated and isolation maintained. Here, we investigated the association of behavioral isolation on population differentiation in Northern Cardinals (Cardinalis cardinalis) distributed across the Cochise Filter Barrier, a region of transitional habitat which separates the Sonoran and Chihuahuan deserts of North America. Using genomewide markers, we modeled demographic history by fitting the data to isolation and isolation‐with‐migration models. The best‐fit model indicated that desert populations diverged in the Pleistocene with low, historic, and asymmetric gene flow across the barrier. We then tested behavioral isolation using reciprocal call‐broadcast experiments to compare song recognition between deserts, controlling for song dialect changes within deserts. We found that male Northern Cardinals in both deserts were most aggressive to local songs and failed to recognize across‐barrier songs. A correlation of genomic differentiation and strong song discrimination is consistent with a model where speciation is initiated across a barrier and maintained by behavioral isolation.

Community phylogeographic patterns reveal how a barrier filters and structures taxa in North American warm deserts

“…We found that there were no qualitative performance differences between the neural network with the 33 original summary statistics and the neural network with the 25 that resulted after the eight were removed (see Appendix S1 for classification information). We assumed a 3-year generation time for the snake species (after Ernst & Ernst, 2003) and a 1-year generation time for the bird species (after Provost et al, 2018).…”

“…To evaluate the performance of our machine learning models on empirical data, we acquired previously published genetic data for four species of snake (Crotalus atrox, Crotalus scutulatus, Pituophis catenifer, and the Lampropeltis getula complex [between L. splendida/L. californiae];Myers et al, 2019) and one species of bird (Cardinalis cardinalis,Provost et al, 2018). All species had used reduced representation sequencing and had generated hundreds to thousands of individual loci, which we analyzed individually for all five taxa.…”

Spatial predictors of genomic and phenotypic variation differ in a lowland Middle American bird (Icterus gularis)

“…Other parameter estimates are shown in the figure. Figure based on Provost, Mauck, Smith (2018) [Colour figure can be viewed at wileyonlinelibrary.com]…”

De NovoAssembly of the Northern Cardinal (Cardinalis cardinalis) Genome Reveals Candidate Regulatory Regions for Sexually Dichromatic Red Plumage Coloration

“…The population started to decline again after the beginning of the Last Glacial Period (LGP). The decrease in effective population size observed at the beginning of Pleistocene might be due to the divergence of C. cardinalis into different subspecies ( Provost et al 2018 ). The population decline after the start of the LGP is consistent with the ecological niche model that indicates a dramatic range reduction for C. cardinalis during the LGP ( Smith et al 2011 ).…”