Uniformity in variety: Antler morphology and evolution in a predator-free environment

[摘要] The Late Pleistocene mammal fauna of Crete was impoverished, as typical for oceanic islands, and consisted only of deer, dwarf elephants, an otter, a shrew and giant mice. Dwarf deer (Candiacervus spp.) were the dominant endemic herbivorous species. Here, I describe the adult antler morphology of this deer. Antler variety appears to be remarkably large, yet a few concise morphological groups without intermediate forms can be recognized, likely representing separate species. Antler variety is not a product of random variation induced by ecological release in a predator-free environment. Three new species are described here (Candiacervus spp. nov.), differing in antler and skull morphology, and the diagnosis of existing species (C. ropalophorus, C. rethymnensis) is emended based on new material. Antler variation can be explained by two evolutionary trends: showiness versus a classic fighting type. Divergence is driven and accelerated by intra-specific competition among males. The classic type is best explained as a result of allometric down-scaling during dwarfism. The display type is best explained as a result of restructuring of antler bauplan (simplification and extreme elongation of the main beam). Under predator-free scenarios, deer have the potential to evolve antler morphologies and behavioural changes unknown on the mainland.

[学科分类] 地质学

[关键词] Alexandra A.E. van der Geer;Candiacervus;endemic deer;new species;adaptive radiation