Molecular systematics, Biogeography, & Evolution of antlers in New & Old World deer (Cervidae)

          Molecular phylogenetic investigation of 23 taxa in 14 genera of Cervidae support a division of deer into two clades, which corresponds to a division into two monophyletic subfamilies based on alternative conditions of the lateral digits. Telemetacarpalian "New World" deer (Odocoileinae, including the only antlerless deer species, Chinese water deer (Hydropotes), can be divided into three monophyletic tribes: Capreolini (Capreolus and Hydropotes), Alceini (Alces only), and Odocoileini (endemic New World deer, including white-tailed and mule deer (Odocoileus) and several genera of poorly-known Neotropical speces as well as holarctic caribou or reindeer (Rangifer)). Most nominal genera of plesiometacarpalian "Old World" deer (Cervinae) (Cervus, Elaphurus, Panolia, Rucervus, Rusa, and Sika) form a compact, well-defined clade, and each can be considered a monophyletic subgenus of Cervus (sensu lato). Axis is the sister to Cervus (sensu lato); either Dama or Muntiacus is the sister to the remaining cervines.

         This phylogeny suggests a fundamental re-evaluation of patterns of morphological and biogeographic evolution in Cervidae. Patterns of antler evolution in Old World deer are re-evaluated. Antlers have evolved only once: Hydropotes shows a secondary loss of antlers and does not represent the plesiomorphic state for cervids. Simple, three-tined antlers as seen in Axis represent the ancestral condition for Cervus (sensu lato); complex, multi-tined antlers in Sika and Cervus (sensu stricto) appear to be evolutionarily derived. In contrast, large, palmate antlers are ancestral for New World deer. as seen in holarctic Rangifer and Alces, and perhaps the extinct Irish Elk (Megaceros). The biogeographic origins of the Neotropical cervids are reconsidered. Endemic South American genera (Ozotoceros, Blastocerus, Hippocamelus, and Pudu) are a distinct and substantially older radiation than are Central and South American Mazama, which are more closely related to Nearctic Odocoileus.  Mazama includes many cryptic  and cytogentically diverse species: one lineage is more closely related to the Neotropical clade, and another to the Nearctic species. Spike antlers in Pudu and Mazama spp. are consequences of convergent allometric size reduction.