Diversity
<p>Bovids are the largest of 10 extant families within Artiodactyla, consisting of more than 140 extant and 300 extinct species. Designation of subfamilies within <span class="taxon">Bovidae</span> has been controversial and many experts disagree about whether <span class="taxon">Bovidae</span> is monophyletic or not. While as many as 10 and as few as 5 subfamilies have been suggested, the intersection of molecular, morphological, and fossil evidence suggests 8 distinct subfamilies: <span class="taxon">Aepycerotinae</span> (impalas), <span class="taxon">Alcelaphinae</span> (bonteboks, hartebeest, wildebeest, and relatives), <span class="taxon">Antilopinae</span> (antelopes, dik-diks, gazelles, and relatives), <span class="taxon">Bovinae</span> (bison, buffalos, cattle, and relatives), <span class="taxon">Caprinae</span> (chamois, goats, serows, sheep, and relatives), <span class="taxon">Cephalophinae</span> (duikers), <span class="taxon">Hippotraginae</span> (addax, oryxes, roan antelopes, sable antelopes, and relatives), and <span class="taxon">Reduncinae</span> (reedbucks, waterbucks, and relatives). Wild bovids can be found throughout Africa, much of Europe, Asia, and North America and characteristically inhabit grasslands. Their <a href="http://animaldiversity.ummz.umich.edu/site/resources/anatomical_images/family_pages/artiodactyla/bovidae3.jpg/medium.jpg">dentition</a>, <a href="http://animaldiversity.ummz.umich.edu/site/resources/anatomical_images/feet_and_legs/posture.jpg?XTHEME=POPUP">unguligrade</a> limb morphology, and gastrointestinal specialization likely evolved as a result of their grazing lifestyle. All bovids have four-chambered, ruminating stomachs and at least one pair of <a href="http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/horns_and_antlers.html">horns</a>, which are generally present on both sexes.<span> (Alder et al., 1995; Feldhamer et al., 2007; Gentry, 2011; Kingdon, 1982a; Kingdon, 1982b; Vaughn, Ryan, and Czaplewski, 2000; Walther, 1990)</span></p> <p>Species in the subfamily <span class="taxon">Bovinae</span> are native to Africa, North America, Eurasia, India, and southern Asia. <span class="taxon">Bovinae</span> is generally considered to include 24 species from 8 different genera, including <span class="taxon"><em>Boselaphus tragocamelus</em></span>, <span class="taxon"><em>Tetracerus quadricornis</em></span>, <span class="taxon"><em>Bos</em></span>, <span class="taxon"><em>Bison</em></span>, <span class="taxon"><em>Bubalus</em></span>, <span class="taxon"><em>Syncerus caffer</em></span>, and <span class="taxon"><em>Tragelaphus</em></span>. Sexual dimorphism is highly prevalent in this subfamily, with the males of some species weighing nearly twice as much as their female counterparts. Bovines have played an important role in the cultural evolution of <span class="taxon"><em>Homo sapiens</em></span>, as numerous species within this subfamily have been domesticated for subsistence purposes.<span> (Estes, 1991; Gentry, 2011; Shackleton and Harested, 2010a; Shackleton and Harested, 2010b)</span></p> <p>The subfamily <span class="taxon">Antilopinae</span> includes antelopes, dik-diks, gazelles, and relatives. Small to medium-sized, cover-dependent antelope are found throughout a majority of Africa but occur in particularly high densities in east Africa. <span class="taxon"><em>Neotragus</em></span>, <span class="taxon"><em>Raphicerus</em></span>, and <span class="taxon"><em>Madoqua</em></span> occur in a variety of different habitats but are also restricted to the continent of Africa. Finally, true gazelles include the genera <span class="taxon"><em>Eudorcas</em></span>, <span class="taxon"><em>Gazella</em></span>, <span class="taxon"><em>Nanger</em></span>, and <span class="taxon"><em>Procapra</em></span>, among others. In general, bovids within the subfamily <span class="taxon">Antilocapinae</span> occur throughout much of Asia and Africa.<span> (Estes, 1991; Gentry, 2011; Shackleton and Harested, 2010a; Shackleton and Harested, 2010b)</span></p> <p>Bovids within the subfamily <span class="taxon">Reduncinae</span> are primarily distributed throughout parts of Eurasia and Africa. <span class="taxon">Reduncinae</span> is comprised of only three genera, including <span class="taxon"><em>Redunca</em></span> (reedbucks), <span class="taxon"><em>Pelea</em></span> (rhebok), and <span class="taxon"><em>Kobus</em></span> (waterbucks). Species in <span class="taxon">Reduncinae</span> are medium to large-sized grazers that often have strong ties to water. They also have long <a href="http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.html">hair</a>, and all species exhibit sexual dimorphism, as <a href="http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/horns_and_antlers.html">horns</a> are only present in males.<span> (Estes, 1991; Gentry, 2011; Shackleton and Harested, 2010a; Shackleton and Harested, 2010b)</span></p> <p>Bovids in the subfamily <span class="taxon">Hippotraginae</span> consist primarily of large grazing antelopes with large horns. <span class="taxon">Hippotraginae</span> species are restricted to Africa and middle-east Asia and are primarily grazers. Most species in this subfamily live in arid habitats and have an erect mane along the nape of the neck. Recent accounts include 8 species from 3 different genera.<span> (Estes, 1991; Gentry, 2011; Huffman, 2011; Shackleton and Harested, 2010a; Shackleton and Harested, 2010b)</span></p> <p><span class="taxon">Ancelaphinae</span>, consisting of 10 species from 4 genera, includes <span class="taxon"><em>Damaliscus</em></span>, <span class="taxon"><em>Alcelaphus</em></span>, <span class="taxon"><em>Connochaetes</em></span>, and relatives. All of the species in this subfamily are nomadic grazers that are native to Africa. Most species are size-dimorphic, with males being 10 to 20% larger than females, and both males and females possess double-curved horns, also known as lyrate.<span> (Estes, 1991; Gentry, 2011; Huffman, 2011; Shackleton and Harested, 2010a; Shackleton and Harested, 2010b)</span></p> <p>The subfamily <span class="taxon">Caprinae</span> consists of <span class="taxon"><em>Capra</em></span>, <span class="taxon"><em>Ovis</em></span>, <span class="taxon"><em>Ovibos moschatus</em></span>, and relatives. This subfamily of bovids consists of 12 genera, however, the organization of <span class="taxon">Caprinae</span> is complex and several classifications have been suggested. The International Union for Conservation of Nature (IUCN) currently has a Taxonomy Working Group within their Caprinae Specialist Group to help alleviate some of the outstanding issues within <span class="taxon">Caprina</span> taxonomy. Caprinids are especially adapted to montane and alpine environments, which explains why this is the only subfamily that is more diverse in Eurasia than Africa. In general, both genders have <a href="http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/horns_and_antlers.html">horns</a>, however, <a href="http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/horns_and_antlers.html">horn</a> morphology in many species is sexually dimorphic.<span> (Estes, 1991; Gentry, 2011; Huffman, 2011; Mallon, 2010)</span></p> <p>The subfamily <span class="taxon">Aepycerotinae</span> consists a single species, the <span class="taxon"><em>Aepyceros melampus</em></span>. <span class="taxon">Aepycerotinae</span> is endemic to Africa and is thought to have diverged from other bovids during the early <img alt="" border="0" height="16" src="http://animaldiversity.ummz.umich.edu/site/link_icon.gif" width="16"></img><a href="http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/guide/geologictimescale.html">Miocene</a>, around 20 million years ago. Impala are sexually dimorphic, as only males possess horns..<span> (Estes, 1991; Huffman, 2011; Kingdon, 1982a; Kingdon, 1982b)</span></p> <p><span class="taxon">Cephalophinae</span> consists of 18 species of duiker from 3 genera. Duikers are highly specialized and are resident to the tropical forests of Africa. All species are easily recognizable as they have the same basic body plan but differ significantly in size from one species to the next. Duikers are size-dimoprhic, however, unlike most bovids, females are slightly larger than males. Also unlike most other bovids, duikers are primarily frugivorous.<span> (Estes, 1991; Huffman, 2011; Nowak, 1999)</span></p>
