Genetic differentiation and hybridization between greater and lesser spotted eagles (Accipitriformes:Aquila clanga, A. pomarina)

Abstract

Greater and lesser spotted eagles (Aquila clanga, A. pomarina) are two closely related forest eagles overlapping in breeding range in east-central Europe. In recent years a number of mixed pairs have been observed, some of which fledged hybrid young. Here we use mitochondrial (control region) DNA sequences and AFLP markers to estimate genetic differentiation and possible gene flow between these species. In a sample of 83 individuals (61 pomarina, 20 clanga, 2 F1-hybrids) we found 30 mitochondrial haplotypes which, in a phylogenetic network, formed two distinct clusters differing on average by 3.0% sequence divergence. The two species were significantly differentiated both at the mitochondrial and nuclear (AFLP) genetic level. However, five individuals with pomarina phenotype possessed clanga-type mtDNA, suggesting occasional gene flow. Surprisingly, AFLP markers indicated that these ''mismatched'' birds (originating from Germany, E Poland and Latvia) were genetically intermediate between the samples of individuals in which mtDNA haplotype and phenotype agreed. This indicates that mismatched birds were either F1 or recent back-cross hybrids. Mitochondrial introgression was asymmetrical (no pomarina haplotype found in clanga so far), which may be due to assortative mating by size. Gene flow of nuclear markers was estimated to be about ten times stronger than for mtDNA, indicating a sex-bias in hybrid fertility in accordance with Haldane's rule. Hybridization between the two species may be more frequent and may occur much further west than hitherto assumed. This is supported by the recent discovery of a mixed pair producing at least one fledgling in NE Germany.

Mitochondrial introgression and replacement between yellowhammers (Emberiza citrinella) and pine buntings (Emberiza leucocephalos) (Aves: Passeriformes)

“…This statistic is based simply on two phenotypes, these being presence or absence of each AFLP band. Because a number of other studies report this statistic (Svensson et al, 2004;Bensch & Åkesson, 2005;Helbig et al, 2005;Parchman, Benkman & Britch, 2006;Toews & Irwin, 2008), for purposes of comparison we also calculated it for our data, using ARLEQUIN, version 3.11 (Excoffier et al, 2005).…”

Molecular phylogeny, morphology and life-history comparisons within Circus cyaneus reveal the presence of two distinct evolutionary lineages

“…In a mitochondrial phylogeny of Sea Eagles (Haliaeetus) genetic distances between seven species of sea eagles varied between 0.3 and 9.8 %. Also, a Cytochrome b sequence divergence of only 1.75 % was found between Greater Spotted Eagle (Aquila clanga) and Lesser Spotted Eagle (A. pomarina) (Helbig et al 2005).…”

Challenges and prospects of population genetic studies in terns (Charadriiformes, Aves)

“…Reports on potential problems encountered during the selection of molecular markers are also im- 686 Faria et al portant to improve general understanding of their dynamics in different groups. For future studies involving population genetics of terns, the utilization of other kinds of molecular markers that have proved to be suitable to conduct genetic studies in other species of birds might be considered, such as nuclear introns (Congdon et al, 2000;Pacheco et al, 2002;Friesen et al, 2005;Whittier et al, 2006), SNPs (Saetre et al, 2001;Bensch et al, 2002) and AFLP (Wang et al, 2003;Boulet et al, 2005;Helbig et al, 2005).…”