A Genetic Approach to the Management and Conservation of the Hartebeest (Alcelaphus Buselaphus) in Kenya
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Date
2014-02-27
Authors
Ouma, Collins
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Abstract
A lot of effort is put on 'proximate' threats to conservation, overlooking the
'ultimate' conservation goals in the process. Ultimately, attempts need to be made to
conserve not just individuals or populations, but processes that have been on-going over
vast geographical space and long evolutionary time, such as gene flow and natural
selection. So far, little is known about these historical processes that decisions affecting the
management of species in fragmented landscapes are always made without any systematic
information. Fortunately, these processes can be largely reconstructed from natural patterns
of DNA sequence variation that persist to the present day within and among populations.
Adopting genetic tools, a suite of evolutionary issues critical to the conservation of
hartebeest (Alcelaphus buselaphus) in Kenya was addressed. This species is naturally
subdivided, but is declining over much of its range in Africa or has already gone locally
extinct. Active management is required to restore and conserve the natural population
structure of this species. However the genetic information needed to form the basis of these
important processes is still lacking.
The objectives of this study were to elucidate the phylogeography and the genetic
structure of hartebeest populations in Kenya, using cytoplasmic (mitochondrial DNA)
markers. The genetic history of Alcelaphus buselaphus lelwel (A.b. lelwel) and A.b. cokii,
and the focal Laikipia population of central Kenya, were emphasized. A minimum of 489
base pairs in the mitochondrial D-Ioop region were sequenced in 75 individuals,
representing 6 localities in Kenya and northern Tanzania, and including two of the 7 extant
hartebeest 'subspecies' (A.b. cokii and A.b. lelwel). Samples were obtained from Laikipia,
Ruma National Park (NP), Naivasha (Kongoni Sanctuary), Nairobi NP, Serengeti NP and
Ngorongoro. The sequence data were then compared to published data from previous
hartebeest studies.
Results reveal that genetic distinctions exist between populations in Kenya, but are
subtle, derived largely from differences in allele frequency, not from fixed allele
differences, or phylogenetically separate lineages. With the exception of Ruma, patterns of
sequence variation, nucleotide and haplotype diversity show that genetic variation within
populations in this study were moderate to high. Most populations within a subspecies
were more closely related to each other than they were to populations assigned to different
subspecies in the study, implying no gene flow between these subspecies. From the pattern
of the distribution of the number of differences between each pair of haplotypes,
populations from Serengeti, Naivasha and Laikipia recorded high stability, Ngorongoro
showed rapid expansion, while Nairobi was shown to have gone through a bottleneck and is
recovering. Ruma was an exception, having very low variation compared to the other
populations, possibly as a result of severe and/or prolonged bottlenecks leading to high
levels of inbreeding in the population.
These findings provide initial genetic criteria on which the Kenyan conservation
authorities can base informed management and restoration policies for locally extinct or
threatened hartebeest populations. It further supports the general principle that hartebeest
populations in Kenya having similar horn morphology can be considered equivalent and
hence interchangeable for management purposes. The present genetic findings point out
that this principal can be applied irrespective of the distance separating populations.
Genetic variation in Ruma, however, may need to be augmented by importing individuals
from another, outbred population, probably Laikipia. Finally, it is emphasized that
management decisions should be based on more than a single criterion, whether
morphological or genetic, particularly one with such an anomalous mode of inheritance as
mtDNA. Additional genetic data, using multiple nuclear markers (preferably
microsatellite), are also required, particularly to address hybridization issues, for which
mitochondrial data alone are uninformative.
Description
Department of Zoological Sciences,68p. The QL 737.U53O9 2004
Keywords
Hartebeests, Hunter's hartebeest, Bovidae