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- Abalaka, Jacinta, et al.
(författare)
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Genetic diversity and population structure of the range restricted rock firefinch Lagonosticta sanguinodorsalis
- 2015
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 16:2, s. 411-418
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the degree of genetic population differentiation is important in conservation genetics for inferring gene flow between populations and for identifying small and isolated threatened populations. We evaluated the genetic variation within and between three populations of the rock firefinch (Lagonosticta sanguinodorsalis), a range restricted firefinch endemic to Nigeria and Cameroon. The populations were closely located (c. 100 km apart) within the species' core distribution in Central Nigeria. We found that the populations had similar levels of gene diversities (H (E) ) and low but significant inbreeding coefficients (F (IS) ). Despite the short distance between populations there was a weak but significant population structure, which indicates that the populations are somewhat isolated and affected by drift within the species' core distribution in Nigeria. The knowledge of the genetic status of the rock firefinch will serve as a foundation to future studies to help understand population demography and for managing and maintaining viable populations.
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| 2. |
- Hoban, Sean, et al.
(författare)
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Genetic diversity targets and indicators in the CBD post-2020 Global Biodiversity Framework must be improved
- 2020
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 248
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Tidskriftsartikel (refereegranskat)abstract
- The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.
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| 3. |
- Jansen van Rensburg, Alexandra, et al.
(författare)
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Ancestral polymorphism at the major histocompatibility complex (MHCII ss) in the Nesospiza bunting species complex and its sister species (Rowettia goughensis)
- 2012
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background: The major histocompatibility complex (MHC) is an important component of the vertebrate immune system and is frequently used to characterise adaptive variation in wild populations due to its co-evolution with pathogens. Passerine birds have an exceptionally diverse MHC with multiple gene copies and large numbers of alleles compared to other avian taxa. The Nesospiza bunting species complex (two species on Nightingale Island; one species with three sub-species on Inaccessible Island) represents a rapid adaptive radiation at a small, isolated archipelago, and is thus an excellent model for the study of adaptation and speciation. In this first study of MHC in Nesospiza buntings, we aim to characterize MHCII ss variation, determine the strength of selection acting at this gene region and assess the level of shared polymorphism between the Nesospiza species complex and its putative sister taxon, Rowettia goughensis, from Gough Island. Results: In total, 23 unique alleles were found in 14 Nesospiza and 2 R. goughensis individuals encoding at least four presumably functional loci and two pseudogenes. There was no evidence of ongoing selection on the peptide binding region (PBR). Of the 23 alleles, 15 were found on both the islands inhabited by Nesospiza species, and seven in both Nesospiza and Rowettia; indications of shared, ancestral polymorphism. A gene tree of Nesospiza MHCII ss alleles with several other passerine birds shows three highly supported Nesospiza-specific groups. All R. goughensis alleles were shared with Nesospiza, and these alleles were found in all three Nesospiza sequence groups in the gene tree, suggesting that most of the observed variation predates their phylogenetic split. Conclusions: Lack of evidence of selection on the PBR, together with shared polymorphism across the gene tree, suggests that population variation of MHCII ss among Nesospiza and Rowettia is due to ancestral polymorphism rather than local selective forces. Weak or no selection pressure could be attributed to low parasite load at these isolated Atlantic islands. The deep divergence between the highly supported Nesospiza-specific sequence Groups 2 and 3, and the clustering of Group 3 close to the distantly related passerines, provide strong support for preserved ancestral polymorphism, and present evidence of one of the rare cases of extensive ancestral polymorphism in birds.
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