Assessing introgressive hybridization between blue wildebeest (Connochaetes taurinus) and black wildebeest (Connochaetes gnou) from South Africa

Introgressive hybridization poses a threat to the genetic integrity of black wildebeest ( Connochaetes gnou ) and blue wildebeest ( Connochaetes taurinu s) populations in South Africa. Black wildebeest is endemic to South Africa and was driven to near extinction in the early 1900s due to habitat des...

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Bibliographic Details
Published in:Conservation genetics 2018-08, Vol.19 (4), p.981-993
Main Authors: Grobler, Paul, van Wyk, Anna M., Dalton, Desiré L., van Vuuren, Bettine Jansen, Kotzé, Antoinette
Format: Article
Language:English
Subjects:
Admixtures
Animal Genetics and Genomics
Bayesian analysis
Biodiversity
Biomedical and Life Sciences
Clustering
Connochaetes gnou
Connochaetes taurinus
Conservation
Conservation Biology/Ecology
Demographics
Ecology
Environmental degradation
Evolutionary Biology
Genetic diversity
Genetic markers
Hunting
Hybridization
Integrity
Life Sciences
Linkage disequilibrium
Markers
Microsatellites
Molecular chains
National parks
Normal distribution
Outbreaks
Plant Genetics and Genomics
Populations
Research Article
Species extinction
Translocation
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Summary:Introgressive hybridization poses a threat to the genetic integrity of black wildebeest ( Connochaetes gnou ) and blue wildebeest ( Connochaetes taurinu s) populations in South Africa. Black wildebeest is endemic to South Africa and was driven to near extinction in the early 1900s due to habitat destruction, hunting pressure and disease outbreaks. Blue wildebeest on the other hand are widely distributed in southern and east Africa. In South Africa the natural distribution ranges of both species overlap, however, extensive translocation of black wildebeest outside of its normal distribution range in South Africa have led to potential hybridization between the two species. The molecular identification of pure and admixed populations is necessary to design viable and sustainable conservation strategies, since phenotypic evidence of hybridization is inconclusive after successive generations of backcrossing. The aim of this study was to assess levels of hybridization in wildebeest using both species-specific and cross-species microsatellite markers. Black wildebeest (157) and blue wildebeest (122) from provincial and national parks and private localities were included as reference material, with 180 putative hybrid animals also screened. A molecular marker panel consisting of 13 cross-species and 11 species-specific microsatellite markers was developed. We used a Bayesian clustering model to confirm the uniqueness of blue- and black wildebeest reference groups, assign individuals to each of the two clusters, and determine levels of admixture. Results indicated a clear partition between black wildebeest and blue wildebeest (the average proportions of membership to black wildebeest and blue wildebeest clusters were QI = 0.994 and QI = 0.955 respectively). From the putative hybrid samples, only five hybrid individuals were confirmed. However, high levels of linkage disequilibrium were observed in the putative hybrid populations which may indicate historical hybridization. Measures of genetic diversity in the black wildebeest populations were found to be lower than that of the blue wildebeest. The observed lower level of genetic diversity was expected due to the demographic history of the specie. This study will make a significant contribution to inform a national conservation strategy to conserve the genetic integrity of both species.
ISSN:1566-0621
1572-9737
DOI:10.1007/s10592-018-1071-x