Genomic and acoustic differences separate Lilian's Meadowlark (Sturnella magna lilianae) from Eastern (S. magna) and Western (S. neglecta) Meadowlarks

<p>Examining differences among recently diverged populations can provide insight into the traits and evolutionary mechanisms that drive or maintain divergence. The genus <i>Sturnella</i> includes two recently diverged species, <i>Sturnella magna </i>(Eastern Meadowlark) and <i>S. neglecta </i>(Western Meadowlark), the former of which has a complex of subspecies distributed across the Americas. Of the <i>S. magna</i> subspecies that occur in the United States, <i>S. m. lilianae </i>is the only one with a disjunct range, occurring in the southwestern U.S. and central Mexico. It also has markedly different song patterns than all other <i>S. magna</i> subspecies. In order to assess population differentiation, we performed whole-genome sequencing of 35 birds, and analyzed song characteristics from 85 birds. Songs from each species and <i>S. m. lilianae</i> were diagnosable using linear discriminant function analysis and support divergence in song between all taxa. Phylogenetic analysis and admixture proportions support three distinct clades within North American meadowlarks, and tests of introgression failed to detect a significant signal. Overall, our results indicate that <i>S. m</i>. <i>lilianae</i> exhibits high levels of genetic and vocal differentiation from both<i> S. magna</i> and <i>S. neglecta</i>, with no evidence of introgression between any group, and forms a distinct evolutionary lineage. We thus recommend the elevation of <i>S. m. lilianae </i>to species status.</p>