Allozyme Divergence within the Bovidae

Abstract

We describe a phylogeny of the Bovidae based on 40 allozyme loci in 27 species, representing 10 of the 14 bovid tribes described by Vrba (1985). Giraffe represented a related family (Giraffidae). A phenogram was derived using the unweighted pair-group method with arithmetic means (UPGMA), based on Nei's genetic distances (ND) between species. A tree was also derived using the neighbor-joining technique, also based on ND. To provide a cladistic interpretation, the data were analyzed by a maximum parsimony method (phylogenetic analysis using parsimony, PAUP). We found marked divergence within the Bovidae, consistent with the appearance of the family in the early Miocene. Unexpectedly, the most divergent species was the impala, which occupied a basal position in all trees. Species in the tribe Alcelaphini were the most derived taxa in all trees. These patterns conflict strongly with the previous taxonomic alliance, based on immuno-distance and anatomical evidence, of the impala as a sister group of the Alcelaphini. All trees agreed that tribes described by Vrba (1985) are monophyletic, except the Neotragini, which was polyphyletic, with suni occupying a long branch by itself. The dikdik and klipspringer were consistently placed as sister taxa to species in the Antilopini. Three tribes (Aepycerotini, Tragelaphini and Cephalophini), whose fossils have not been found outside Africa, were basal in all trees, suggesting that bovids originated in Africa. Nodes connecting the remaining tribes were closely clustered, a pattern that agrees with fossil evidence of rapid divergence within the Bovidae in the mid-Miocene (about 15 mybp). The allozyme data suggested a second phase of rapid divergence within tribes during the Plio-Pleistocene, a pattern that also agrees with fossil evidence. Rates of bovid divergence have therefore been far from constant. However, the clustering of nodes imparts considerable uncertainty to the branching order leading to the derived tribes, and to a lesser extent, species within tribes. The classical division of the Bovidae into the Boodontia and Aegeodontia does not agree with the phylogenetic grouping of tribes presented in this analysis. However, the maximum parsimony tree derived using 'local' branch swapping clustered all grazing species into a derived, monophyletic group, suggesting that grazing may have evolved only once in bovid evolution.

Estimating the Transition/Transversion Ratio from Independent Pairwise Comparisons with an Assumed Phylogeny

“…First, this mode of analysis can be applied only when a plausible phylogeny of at least some of the taxa Carroll 1989;Catzeflis et al 1989Catzeflis et al , 1992Eisenberg 1981;Forstén 1992;Georgiadis et al 1990;Geraads 1992;Hafner 1984;Hartl et al 1988Hartl et al , 1990 is available from other lines of evidence. Second, if the true phylogeny differs markedly from the estimated phylogeny used in the analysis, the results could be meaningless.…”

Phylogenomic study of spiral-horned antelope by cross-species chromosome painting

“…Cranial similarities suggest a sister relationship between T. spekei and T. angasi and between T. imberbis and T. strepsiceros respectively (Kingdon 1982, Alden et al 1995, while the presence of horns in both sexes of T. euryceros and the two Taurotragus species, T. oryx and T. derbianus, are thought to indicate a close evolutionary affinity among these species (Gentry 1992). In sharp contrast, recent studies using mtDNA data, or combined nuclear intron and mitochondrial DNA sequences, in conjunction with comprehensive taxon representation failed to provide genetic support for the recognition of three tragelaphid genera, or for any of the sister species relationships outlined above (Matthee & Robinson 1999, Willows-Munro et al 2005; see also Georgiadis et al 1990, Essop et al 1997, Gatesy et al 1997.…”

Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex

“…Due to pronounced differences in the social organisation among species, tragelaphine antelopes are also an ideal model for a comparative approach to examine the evolution of social behaviour, gregariousness, and social systems in relation to ecological constraints (Leuthold 1974;Owen-Smith 1976;Hillman 1987;Klaus-Hu¨gi et al 2000;Magliocca et al 2002;Wronski 2005;Wronski and Apio 2006). Previous molecular studies included the genera Taurotragus (Georgiadis et al 1990;Gatesy et al 1997;Matthee and Robinson 1999;Hassanin and Douzery 1999) and Booceros (Matthee and Robinson 1999) into Tragelaphus, supporting the idea that several closely related, yet phenotypically divergent tragelaphines have evolved. Moreover, paraphyly was found in phenotypically similar presumed sister taxa, such as lowland nyala (T. angasi) and mountain nyala (T. buxtoni) and the greater (T. strepsiceros), and lesser kudu (T. imberbis), suggesting convergent evolution of similar phenotypes in these cases (Matthee and Robinson 1999;WillowsMunro et al 2005).…”