Conservation genetics of the threatened horned grebe (Podiceps auritus L.) population of the Magdalen Islands, Quebec. Conserv Genet

The horned grebe (Podiceps auritus) population of the Magdalen Islands in the St. Lawrence Gulf (Québec, Canada) has declined sharply over the last decades. It is the only breeding population of this species in eastern North America with nearest breeding populations being>2500 km apart in western North America and Europe, We used three types of genetic markers: mitochondrial (mt) DNA ND2 sequence, a-enolase intron sequence, and 25 amplified fragment length polymorphism loci (AFLPs) to quantify the genetic diversity within the Magdalen Island population and to assess its genetic distinc-tiveness relative to populations from western Canada (five sites) and Iceland (one site). The Magdalen Island population retained a comparable amount of genetic diversity to the average diversity observed across all populations in all three markers. Horned grebe mtDNA sequences formed a monophyletic group and nearly all haplotypes present in Québec were found elsewhere. In the ND2 fragment, popu-lations partitioned into two groups corresponding to subspecies (Iceland versus North American sites) and more strongly in three groups according to geographic disjunctions (Iceland versus Québec versus western Canada). In contrast, there was no evidence of structure between sites in the a-enolase intron. In the AFLPs, Iceland showed the greatest level of differentiation, followed by the Québec and British Columbia populations. For conservation purposes, we suggest that the Magdalen Islands population should be recognized as a separate unit