(Un-)expected nocturnal activity in "Diurnal" Lemur catta supports cathemerality as one of the key adaptations of the lemurid radiation.

摘要: The ability to operate during the day and at night (i.e., cathemerality) is common among mammals but has rarely been identified in primates. Adaptive hypotheses assume that cathemerality represents a stable adaptation primates, while nonadaptive propose it result of an evolutionary disequilibrium arising from human impacts on natural habitats. Madagascar offers unique opportunity study evolution activity patterns as there we find monophyletic primate radiation shows nocturnal, diurnal, cathemeral patterns. However, when why evolved lemurs subject intense debate. Thus far, this pattern regularly observed only three lemurid genera actual number lemur species exhibiting yet unknown. Here show ring-tailed lemur, Lemur catta, previously considered be can fact wild. In neighboring distinct forest areas these exhibited either mainly diurnal or activity. We found that, other lemurs, was entrained by photoperiod masked nocturnal luminosity. Our results confirm relationship between transitional eye anatomy physiology 24-h activity, thus supporting adaptive scenario. Also, basis most recent strepsirrhine phylogenetic reconstruction, using parsimony criterion, our findings suggest pushing back emergence stem lemurids. Flexible over could have one key adaptations early possibly driven Madagascar's island ecology. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.