An osteological documentation of hybrid wildebeest and its bearing on black wildebeest (Connochaetes Gnou) evolution
Date
2008-05-14T12:24:04Z
Authors
De Klerk, Bonita
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Abstract
ABSTRACT
Wildebeest are part of the sub family Alcelaphinae and the genus Connochaetes.
There are two extant species of wildebeest namely Connochaetes gnou (black
wildebeest) and Connochaetes taurinus (blue wildebeest). From fossil evidence, it
is thought that co-generic blue and black wildebeest diverged ca. 1Ma.
Historically, geographic ranges of these two species have overlapped, but
different social behaviour and habitat preference prevented sexual interaction. It
has been proposed that reproductive isolation between C. taurinus and C. gnou
may have disappeared due to artificial management. This has caused mate choice
to change in the absence of species-specific mates, resulting in hybridisation.
Most documented cases of hybridisation have occurred from dispersing blue
wildebeest bulls introgressing into black herds however, the opposite has been
observed. Genetic studies on a population where the blue males have introgressed
with black females, show that the blue wildebeest populations are “pure” and that
the black wildebeest populations are receiving an influx of blue alleles. In this
research, 14 skeletons of modern hybrid Connochaetes taurinus and
Connochaetes gnou, from more than one post-hybridisation generation from the
Spioenkop reserve, were morphologically as well as metrically compared with a
sample of ten modern “pure” blue and 15 black wildebeest. This project showed
that univariate, bivariate statistical analyses of selected measurements of the
skeletons were successful in identifying all of the Spioenkop individuals as
hybrids. Morphologically, the hybrids exhibit a general increase in body size, and have unusual horns. The auditory bullae of the Spioenkop specimens are highly
deformed, as are some axes. There is unusual bone growth on most of the post
crania, morphological differences are observed on the distal ends of the
metapodials, and the radius and ulna are fused in many specimens.
Description
Keywords
Connochaetes gnou, hybridization, osteology