| 1. |
- Geffen, Eli, et al.
(author)
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Sea ice occurrence predicts genetic isolation in the Arctic fox
- 2007
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In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 16:20, s. 4241-4255
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Journal article (peer-reviewed)abstract
- Unlike Oceanic islands, the islands of the Arctic Sea are not completely isolated from migration by terrestrial vertebrates. The pack ice connects many Arctic Sea islands to the mainland during winter months. The Arctic fox (Alopex lagopus), which has a circumpolar distribution, populates numerous islands in the Arctic Sea. In this study, we used genetic data from 20 different populations, spanning the entire distribution of the Arctic fox, to identify barriers to dispersal. Specifically, we considered geographical distance, occurrence of sea ice, winter temperature, ecotype, and the presence of red fox and polar bear as nonexclusive factors that influence the dispersal behaviour of individuals. Using distance-based redundancy analysis and the BIOENV procedure, we showed that occurrence of sea ice is the key predictor and explained 40-60% of the genetic distance among populations. In addition, our analysis identified the Commander and Pribilof Islands Arctic populations as genetically unique suggesting they deserve special attention from a conservation perspective.
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| 2. |
- Hailer, Frank, et al.
(author)
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Bottlenecked but long-lived : high genetic diversity retained in white-tailed eagles upon recovery from population decline
- 2006
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In: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 2:2, s. 316-319
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Journal article (peer-reviewed)abstract
- Most of the white-tailed eagle (Haliaeetus albicilla) populations in Europe experienced dramatic declines during the twentieth century. However, owing to intense conservation actions and the ban of DDT and other persistent pollutants, populations are currently recovering. We show that despite passing through demographic bottlenecks, white-tailed eagle populations have retained significant levels of genetic diversity. Both genetic and ringing data indicate that migration between populations has not been a major factor for the maintenance of genetic variability. We argue that the long generation time of eagles has acted as an intrinsic buffer against loss of genetic diversity, leading to a shorter effective time of the experienced bottleneck. Notably, conservation actions taken in several small sub-populations have ensured the preservation of a larger proportion of the total genetic diversity than if conservation had focused on the population stronghold in Norway. For conservation programmes targeting other endangered, long-lived species, our results highlight the possibility for local retention of high genetic diversity in isolated remnant populations.
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| 3. |
- Hailer, Frank, et al.
(author)
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Phylogeography of the white-tailed eagle, a generalist with large dispersal capacity
- 2007
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In: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 34:7, s. 1193-1206
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Journal article (peer-reviewed)abstract
- Aim Late Pleistocene glacial changes had a major impact on many boreal and temperate taxa, and this impact can still be detected in the present-day phylogeographic structure of these taxa. However, only minor effects are expected in species with generalist habitat requirements and high dispersal capability. One such species is the white-tailed eagle, Haliaeetus albicilla, and we therefore tested for the expected weak population structure at a continental level in this species. This also allowed us to describe phylogeographic patterns, and to deduce Ice Age refugia and patterns of postglacial recolonization of Eurasia. Location Breeding populations from the easternmost Nearctic (Greenland) and across the Palaearctic (Iceland, continental Europe, central and eastern Asia, and Japan). Methods Sequencing of a 500 base-pair fragment of the mitochondrial DNA control region in 237 samples from throughout the distribution range. Results Our analysis revealed pronounced phylogeographic structure. Overall, low genetic variability was observed across the entire range. Haplotypes clustered in two distinct haplogroups with a predominantly eastern or western distribution, and extensive overlap in Europe. These two major lineages diverged during the late Pleistocene. The eastern haplogroup showed a pattern of rapid population expansion and colonization of Eurasia around the end of the Pleistocene. The western haplogroup had lower diversity and was absent from the populations in eastern Asia. These results suggest survival during the last glaciation in two refugia, probably located in central and western Eurasia, followed by postglacial population expansion and admixture. Relatively high genetic diversity was observed in northern regions that were ice-covered during the last glacial maximum. This, and phylogenetic relationships between haplotypes encountered in the north, indicates substantial population expansion at high latitudes. Areas of glacial meltwater runoff and proglacial lakes could have provided suitable habitats for such population growth. Main conclusions This study shows that glacial climate fluctuations had a substantial impact on white-tailed eagles, both in terms of distribution and demography. These results suggest that even species with large dispersal capabilities and relatively broad habitat requirements were strongly affected by the Pleistocene climatic shifts.
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| 4. |
- Helander, Björn, 1946-, et al.
(author)
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Morphological and genetic sex identification of white-tailed eagle Haliaeetus albicilla nestlings
- 2007
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In: Journal of Ornithology = Journal fur Ornithologie. - : Springer Science and Business Media LLC. - 0021-8375 .- 1439-0361. ; 148:4, s. 435-442
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Journal article (peer-reviewed)abstract
- Identifying the sex of bird nestlings is relevant to studies of behaviour and ecology and is often a central issue in the management of endangered or captive populations. The white-tailed eagle Haliaeetus albicilla is a formerly threatened Eurasian raptor which is closely monitored in many countries due to its high exposure to environmental pollutants in the food chain. The aim of this study was to evaluate the reliability of sex identification methods for white-tailed eagle nestlings based on morphological measurements that can be recorded at the nest by a single person and with minimum disturbance. The sex of each bird was independently determined using molecular (genetic) methods. One measure of tarsus width allowed the correct identification of sex for 96% of the nestlings from southern and central Sweden. However, we found that the criteria for sex identification were not directly applicable to the population in Swedish Lapland, where nestlings are typically thinner, probably due to a limited food supply. These results show that sexing in the field of white-tailed eagle nestlings can be feasible with high accuracy based on a limited number of measurements. However, the criteria employed to separate sexes may have to be adjusted for each population.
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