1 School of Culture, History and Languages, Australian National University, Canberra ACT, Australia; 2 School of Social Science, The University of Queensland, Brisbane Qld, Australia Phylogenetic topology mapped onto dietary ecospace reveals multiple pathways in the evolution of the herbivorous niche in African Bovidae J ULIEN LOUYS 1 and J. TYLER FAITH 2 Abstract Understanding the evolutionary history of the herbivore niche within African bovids has traditionally relied on examining anatomical adaptations to diet, particularly those related to digestive strategy. More recently, mesowear and stable isotope analyses have been used to great effect to reconstruct dietary preferences. We use these dietary proxies to construct a morphology-free dietary ecospace and examine the topology of the phylogenetic rela- tionships of African bovids mapped onto this ecospace. The reconstructed dietary ecospace provides evidence for four distinct dietary classes: species with C3- or C4-dominated diets that produce low or high occlusal relief, likely related to diets high or low in abrasives, respectively. We detected no evidence for a discrete mixed feeder category; the species often categorized as such represent the end members of groups of species with either C3- or C4- dominated diets. Our analysis reveals high variability within the C4 grazing ecospace, and phylogenetic evidence indicates at least two pathways to grazing, likely related to the abrasive qualities of ingested food, which may be determined by the moisture content or the height of consumed grasses. These different pathways probably contribute to the high diversity of African grazers, both today and in the fossil record. C3 browsers (non- frugivores) also display a high degree of variation, but there are no species associated with highly abrasive diets and there is evidence for only a single evolutionary pathway. We find evidence for only one evolutionary route towards frugivory, which includes species with diets that produce both high and low occlusal reliefs. The cause of abrasive wear in frugivores may be related to grit and/or the hard parts of fruits, but this requires further examination. Key words: Browser – grazer – frugivore – mesowear – stable isotope Introduction Africa hosts a large diversity of environments, ranging from deserts to savannahs and tropical rain forests. One group of large mammals that has evolved to exploit this environmental diversity arguably more than any other are the African bovids (family Bovidae). Although they are also found in Eurasia and North America, the greatest bovid diversity is in Africa, where they are represented by 31 genera and 82 extant species (IUCN Red List 2012), with more than 100 extinct species known from the fossil record (Gentry 2010). They range in size from approximately 3 kg (Neotragus pygmaeus Linneaus, 1758) up to approximately 900 kg (Syncerus caffer Sparrman, 1779) and are found through- out the range of African environments. The diversity of African bovids compared with other lineages is thought to have been driven by their successful exploitation of complex grassland mosaics that began to expand towards the end of the Miocene (Bobe 2006) mediated by their ability to make use of a wide range of food resources; dietary preferences amongst extant bovids range from strict grazing to browsing–grazing intermedi- ates to browsing and frugivory (Hofman and Stewart 1972; Kingdon 1982; Bodmer 1990; Estes 1991; Gagnon and Chew 2000). Most dietary studies on African bovids examine differ- ences between grazing and browsing lifestyles, and the diversifi- cation of the group is generally understood through an examination of this grazer–browser dichotomy (e.g. Bobe 2006; Clauss et al. 2008; Janis 2008). Frugivory, although not as inten- sively studied as the development of grazing, nevertheless repre- sents a unique specialization within the Bovidae (Bodmer 1990; Gagnon and Chew 2000) and evolved at least once in the Cepha- lophini. Understanding the evolutionary history of the herbivore niche within African bovids has traditionally relied on examining anatomical adaptations to diet, particularly those related to diges- tive strategy (Clauss et al. 2003; Codron et al. 2008a). From a palaeontological point of view, morphological characters discern- ible in the fossil record, such as anterior dentary shape, mandible shape and size and hypsodonty index, have been used to inform on the dietary preferences of both extant and extinct species (e.g. Gordon and Illius 1988; Solounias and Dawson-Saunders 1988; Solounias et al. 1988, 1995; Janis 1990, 1995, 2008; Solounias and Moelleken 1993; P erez-Barberia and Gordon 1999, 2001; MacFadden 2000; Williams and Kay 2001; Mendoza et al. 2002; Solounias and Semprebon 2002; Feranec 2007; Mendoza and Palmqvist 2007; Codron et al. 2008b; Faith et al. 2011, 2012; Fraser and Theodor 2011). However, the significance of some of these traits in identifying dietary preferences has been re-exam- ined in the light of the potentially confounding effects of phylo- genetic affinity (P erez-Barberia and Gordon 1999, 2001; Clauss et al. 2008; Raia et al. 2010). Increasingly, anatomical studies are being conducted within a phylogenetic framework, such that the influence of shared ancestry can be quantified (P erez-Barberia and Gordon 2001; Meloro et al. 2008; Raia et al. 2010). While morphological traits associated with dietary preferences have plausible functional adaptive value (Raia et al. 2010), within some species at least, novel diets, or those at least different to ancestral species may belie phenotypic expression. Understanding the dietary diversity of both extant and extinct bovids in the last decade has benefited enormously from the application of stable isotopic analyses (e.g. Sponheimer et al. 1999, 2003a,b,c; Cerling et al. 2003; Codron et al. 2005a,b, 2007a,b, 2008b). Unlike morphological analyses of dietary pref- erences, where adaptations to particular dietary niches may be influenced by shared phylogenetic history, stable isotopes pro- vide a direct record of an animal’s diet. Traditionally, carbon sta- ble isotopic signatures of animal tissues, such as enamel, keratin and faeces, have been quantified, with the resulting data used to infer grazing or browsing preferences (Cerling et al. 2003; Spon- heimer et al. 2003b; Codron et al. 2005a,b, 2007a,b). This proce- dure makes use of the different photosynthetic pathways of most tropical grasses (C4) versus all trees and most herbs and shrubs (C3) (see review in Ehleringer and Monson 1993). Likewise, dental wear proxies such as microwear and mesowear provide dietary data considered independent of Corresponding author: Julien Louys (jclouys@gmail.com) Contributing authors: Julien Louys (jclouys@gmail.com), J. Tyler Faith (j.faith@uq.edu.au) Accepted on 27 June 2014 © 2014 Blackwell Verlag GmbH J Zoolog Syst Evol Res doi: 10.1111/jzs.12080