Amak Island Song Sparrows (Melospiza melodia amaka) are not evolutionarily significant

Abstract

The conservation status and evolutionary distinctiveness of the isolated, small, and endemic population of Amak Island Song Sparrows (Melospiza melodia amaka) have been equivocal. Coupled with a reassessment of phenotypic evidence for this taxon, we used mitochondrial cytochrome b sequences and eight microsatellite loci to evaluate the relationship of the Amak population to nearby Song Sparrow populations. Phenotypically, M. m. amaka is not a valid taxon, and we found that Amak Song Sparrows possess no unique haplotypes and have allele frequencies and heterozygosity values similar to those in other populations. Congruence between genetic and morphological evidence suggesting no diagnosable differences leads us to propose that this population is not an evolutionarily significant unit (ESU), not a valid subspecies, not a distinct population segment (DPS), nor a diagnosable conservation unit, but rather a sink colonized by regional source populations.