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Comparative Molecular Genetic Analysis on the Phylogeny of Equids with Special Reference to Equus hemionus kulan and Equus hemionus onager

Karin Krger, 2003

Veterinärmedizinische Fakultät, Institut fr Nutztierwissenschaften, Gruppe Zchtungsbiologie

Contact: gerald.stranzinger@inw.agrl.ethz.ch

The phylogeny and evolution of equids were at the center of this study. In addition, the problems of conservation were discussed. The essential question was whether individuals and populations of E. hemionus onager and E.hemionus kulan could be differentiated by means of microsatellite markers.

31 microsatellites, distributed on all autosomal chromosomes of the horse (2n=64) and completed with a marker on the X-chromosome, served as the base for this study. Through those markers, 120 equids from 11 different populations were genotyped (3840 genotypes). The 11 populations belonged to three groups of E.asinus asinus, one group of E.africanus somaliensis, four populations of Asiatic wild asses (E.hemionus sbsp. and E.kiang), as well as one group each of E.burchelli, E.ferus przewalskii and E.caballus caballus. The generated multilocus genotypes were analysed with statistical programs developed especially for questions of phylogeny. The analysis used the ?allele-sharing? approach, which resulted in clear differentiations between all tested populations. Phylogenetic analyses by means of (__)_ showed periods of divergence for populations that were comparable to already published data based on mitochondrial DNA and fossils. The application of a multivariate correspondence analysis confirmed the results obtained from ?allele sharing? and made the single populations groupings clearly discernible. The hypothesis of the exclusive genetic origin of all domesticated donkeys from the African wild donkey was confirmed repeatedly from the acquired data.

The results of the assignment methods according to Bayes suggest that generally, bigger random samples are necessary in order to definitely assign even unclear cases to a population. However, about 83% of the animals could be assigned correctly with a high degree of certainty in this study, in spite of a relatively limited number of equids. On the whole, it became apparent that there are differences on the level of microsatellite markers between E.h.onager and E.h.kulan which are sufficient to identify single animals from the respective subspecies in a bigger and more representative sample.

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