| 1. |
- Bidon, Tobias, et al.
(författare)
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Brown and Polar Bear Y Chromosomes Reveal Extensive Male-Biased Gene Flow within Brother Lineages
- 2014
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 31:6, s. 1353-1363
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Tidskriftsartikel (refereegranskat)abstract
- Brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial DNA (mtDNA) or were geographically restricted. The male-specific Y chromosome, a natural counterpart to mtDNA, has remained underexplored. Although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most mammals. We developed 13 novel Y-chromosomal sequence and microsatellite markers from the polar bear genome and screened these in a broad geographic sample of 130 brown and polar bears. We also analyzed a 390-kb-long Y-chromosomal scaffold using sequencing data from published male ursine genomes. Y chromosome evidence support the emerging understanding that brown and polar bears started to diverge no later than the Middle Pleistocene. Contrary to mtDNA patterns, we found 1) brown and polar bears to be reciprocally monophyletic sister (or rather brother) lineages, without signals of introgression, 2) male-biased gene flow across continents and on phylogeographic time scales, and 3) male dispersal that links the Alaskan ABC islands population to mainland brown bears. Due to female philopatry, mtDNA provides a highly structured estimate of population differentiation, while male-biased gene flow is a homogenizing force for nuclear genetic variation. Our findings highlight the importance of analyzing both maternally and paternally inherited loci for a comprehensive view of phylogeographic history, and that mtDNA-based phylogeographic studies of many mammals should be reevaluated. Recent advances in sequencing technology render the analysis of Y-chromosomal variation feasible, even in nonmodel organisms.
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| 2. |
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| 4. |
- Dearborn, Donald C., et al.
(författare)
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Microsatellite Primers for Relatedness and Population Structure in Great Frigatebirds (Pelecaniformes: Fregatidae)
- 2008
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 8:6, s. 1399-1401
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Tidskriftsartikel (refereegranskat)abstract
- Eighteen moderately polymorphic microsatellite loci were isolated and characterized for great frigatebirds Fregata minor. Polymorphism for the 12 dinucleotide and six tetranucleotide markers was assessed in 23 birds from a Hawaii population. Allelic diversity ranged from two to 12 (mean 5.9), with observed heterozygosity from 0.304 to 0.956 (mean 0.637). Three loci showed homozygote excess, possibly due to null alleles. One additional pair of loci exhibited strong gametic disequilibrium. Thus, at least 14 loci will be useful for studies of relatedness and population structure
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| 5. |
- Dowling, Damian k., et al.
(författare)
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Intergenomic epistasis for fitness : Within-population interactions between cytoplasmic and nuclear genes in Drosophila melanogaster
- 2007
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Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 175:1, s. 235-244
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Tidskriftsartikel (refereegranskat)abstract
- The symbiotic relationship between the mitochondrial and nuclear genomes coordinates metabolic energy production and is fundamental to life among eukaryotes. Consequently, there is potential for strong selection to shape interactions between these two genomes. Substantial research attention has focused on the possibility that within-population sequence polymorphism in mitochondrial DNA (mtDNA) is maintained by mitonuclear fitness interactions. Early theory predicted that selection will often eliminate mitochondrial polymorphisms. However, recent models demonstrate that intergenomic interactions can promote the maintenance of polymorphism, especially if the nuclear genes involved are linked to the X chromosome. Most empirical studies to date that have assessed cytonuclear fitness interactions have studied variation across populations and it is still unclear how general and strong such interactions are within populations. We experimentally tested for cytonuclear interactions within a laboratory population of Drosophila melanogaster using 25 randomly sampled cytoplasmic genomes, expressed in three different haploid nuclear genetic backgrounds, while eliminating confounding effects of intracellular bacteria (e.g., Wolbachia). We found sizable cytonuclear fitness interactions within this population and present limited evidence suggesting that these effects were sex specific. Moreover, the relative fitness of cytonuclear genotypes was environment specific. Sequencing of mtDNA (2752 bp) revealed polymorphism within the population, suggesting that the observed cytoplasmic genetic effects may be mitochondrial in origin.
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| 6. |
- Hailer, Frank, et al.
(författare)
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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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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 2:2, s. 316-319
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Hailer, Frank, 1976-
(författare)
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Conservation Genetics of the White-Tailed Eagle
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The white-tailed eagle is a formerly threatened raptor that is commonly used as a flagship and indicator species in conservation work. This thesis uses molecular genetic methods to study sex determination of nestlings, genetic variability, population structure and phylogeography of the white-tailed eagle.Fourteen microsatellite markers were developed and tested for the white-tailed eagle.A method to sex white-tailed eagle nestlings in the field is presented. The method is based on just one tarsus measure, and is suitable for situations where a single person is handling the nestlings alone in a treetop.Most European white-tailed eagle populations underwent extreme declines during the 20th century. The results presented here show that bottlenecked populations have maintained significant levels of genetic diversity. Gene flow between regions is not a main explanation for this, as indicated by both genetic and ringing data. Instead, the long generation time of white-tailed eagles has acted as an intrinsic buffer against rapid loss of genetic diversity. Additionally, local conservation led to protection of more genetic diversity than if conservation had focused on the large remnant population in Norway.Mitochondrial DNA of white-tailed eagles is structured in two main clades with a predominantly eastern and western Eurasian distribution. The clades likely correspond to separate Ice Age refugia but do not grant classification as evolutionary significant units given their current extensive overlap across large parts of Eurasia.Microsatellite variation was studied in populations across Eurasia. Variability was rather constant across the continent, but clearly lower on Iceland and Greenland. This is best explained by founder effects during their colonisation, but only weak bottlenecks during colonisation of and persistence on the continent. Current population differentiation between Europe and eastern Eurasia is not compatible with a zero gene flow model but requires some amount of gene flow over evolutionary time scales.
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| 8. |
- Hailer, Frank, et al.
(författare)
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Development and multiplex PCR amplification of novel microsatellite markers in the White-tailed Sea Eagle, Haliaeetus albicilla (Aves: Falconiformes, Accipitridae)
- 2005
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Ingår i: Molecular Ecology Notes.. - : Wiley. - 1471-8278 .- 1471-8286. ; 5, s. 938-940
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Tidskriftsartikel (refereegranskat)abstract
- We report the development of 14 novel polymorphic microsatellite markers cloned from theWhite-tailed Sea Eagle, Haliaeetus albicilla, a formerly threatened raptor that has receivedmuch conservation attention throughout Eurasia. We also present a protocol for multiplexpolymerase chain reaction (PCR) amplification of the loci. Among 40 unrelated H. albicillaindividuals from southern Sweden, the markers produced two to eight alleles per locus,and average observed and expected heterozygosities were 0.463 and 0.468, respectively. Wefurther present five microsatellite markers that appeared monomorphic in H. albicilla, butwhich may be of interest for use in other raptor species
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| 9. |
- Hailer, Frank, et al.
(författare)
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Hybridization among Three Native North American Canis Species in a Region of Natural Sympatry
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:10, s. e3333-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Population densities of many species throughout the world are changing due to direct persecution as well as anthropogenic habitat modification. These changes may induce or increase the frequency of hybridization among taxa. If extensive, hybridization can threaten the genetic integrity or survival of endangered species. Three native species of the genus Canis, coyote (C. latrans), Mexican wolf (C. lupus baileyi) and red wolf (C. rufus), were historically sympatric in Texas, United States. Human impacts caused the latter two to go extinct in the wild, although they survived in captive breeding programs. Morphological data demonstrate historic reproductive isolation between all three taxa. While the red wolf population was impacted by introgressive hybridization with coyotes as it went extinct in the wild, the impact of hybridization on the Texas populations of the other species is not clear. Methodology/Principal Findings: We surveyed variation at maternally and paternally inherited genetic markers (mitochondrial control region sequence and Y chromosome microsatellites) in coyotes from Texas, Mexican wolves and red wolves from the captive breeding programs, and a reference population of coyotes from outside the historic red wolf range. Levels of variation and phylogenetic analyses suggest that hybridization has occasionally taken place between all three species, but that the impact on the coyote population is very small. Conclusion/Significance: Our results demonstrate that the factors driving introgressive hybridization in sympatric Texan Canis are multiple and complex. Hybridization is not solely determined by body size or sex, and density-dependent effects do not fully explain the observed pattern either. No evidence of hybridization was identified in the Mexican wolf captive breeding program, but introgression appears to have had a greater impact on the captive red wolves.
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| 10. |
- Hailer, Frank, et al.
(författare)
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Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage
- 2012
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 336:6079, s. 344-347
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.
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