Avian hemoglobin variation in a widespread elevational generalist bird

We examined the signature of spatially-varying selection across two parallel elevational transects in all avian hemoglobin loci in a widespread elevational generalist, the Hooded Siskin (Spinus magellanicus). We compared the signature of selection at nonsynonymous sites in all seven hemoglobin loci to autosomal coding regions distributed across the genome using a custom target capture sequencing approach. We found three nonsynonymous sites in hemoglobin loci that show a signature of spatially varying selection with elevation, including in two loci which contribute to embryonic hemoglobin isoforms in passerines.