Abstract
BackgroundThe Osprey (Pandion haliaetus) is one of only six bird species with an almost world-wide distribution. We aimed at clarifying its phylogeographic structure and elucidating its taxonomic status (as it is currently separated into four subspecies). We tested six biogeographical scenarios to explain how the species’ distribution and differentiation took place in the past and how such a specialized raptor was able to colonize most of the globe.ResultsUsing two mitochondrial genes (cyt b and ND2), the Osprey appeared structured into four genetic groups representing quasi non-overlapping geographical regions. The group Indo-Australasia corresponds to the cristatus ssp, as well as the group Europe-Africa to the haliaetus ssp. In the Americas, we found a single lineage for both carolinensis and ridgwayi ssp, whereas in north-east Asia (Siberia and Japan), we discovered a fourth new lineage. The four lineages are well differentiated, contrasting with the low genetic variability observed within each clade. Historical demographic reconstructions suggested that three of the four lineages experienced stable trends or slight demographic increases. Molecular dating estimates the initial split between lineages at about 1.16 Ma ago, in the Early Pleistocene.ConclusionsOur biogeographical inference suggests a pattern of colonization from the American continent towards the Old World. Populations of the Palearctic would represent the last outcomes of this colonization. At a global scale the Osprey complex may be composed of four different Evolutionary Significant Units, which should be treated as specific management units. Our study brought essential genetic clarifications, which have implications for conservation strategies in identifying distinct lineages across which birds should not be artificially moved through exchange/reintroduction schemes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0535-6) contains supplementary material, which is available to authorized users.
Highlights
The Osprey (Pandion haliaetus) is one of only six bird species with an almost world-wide distribution
Phylogenetic relationships For the mitochondrial cyt b dataset (213 individuals = 209 ospreys + 4 outgroups), the best-fit scheme was a partitioning according to codon position with the models HKY + I for position 1 (367 nucleotides), TrN for position 2 (368) and K80 + G for position 3 (368)
No genetic structure was evidenced and it can be noticed that Caribbean samples belong to two haplotypes which are scattered with other carolinensis samples (Fig. 3)
Summary
The Osprey (Pandion haliaetus) is one of only six bird species with an almost world-wide distribution. The modern distribution of living organisms has been shaped by multiple processes that had profound effects on the dispersal, genetic structure and evolutionary histories of plant and animal populations. The Osprey is a medium-sized raptor with flexible breeding habitat requirements across its range. One could predict that such broad habitat tolerances and high mobility should homogenize genomes, limiting genetic differentiation across populations at a continental level, as described in other widespread raptors (e.g. Haliaeetus albicilla: [7]; Falco peregrinus: [8]). Adult ospreys tend to return to their natal area to breed [9] and such strong philopatry may have played in favour of genetic structuring among populations across the extensive range. Genetic differences may be expected between long-distance migratory and partially migratory/resident populations
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