Lemur Biorhythms and Life History Evolution.
Skeletal histology supports the hypothesis that primate life histories are regulated by a neuroendocrine rhythm, the Havers-Halberg Oscillation (HHO). Interestingly, subfossil lemurs are outliers in HHO scaling relationships that have been discovered for haplorhine primates and other mammals. We present new data to determine whether these species represent the general lemur or strepsirrhine condition and to inform models about neuroendocrine-mediated life history evolution. We gathered the largest sample to date of HHO data from histological sections of primate teeth (including the subfossil lemurs) to assess the relationship of these chronobiological measures with life history-related variables including body mass, brain size, age at first female reproduction, and activity level. For anthropoids, these variables show strong correlations with HHO conforming to predictions, though body mass and endocranial volume are strongly correlated with HHO periodicity in this group. However, lemurs (possibly excepting Daubentonia) do not follow this pattern and show markedly less variability in HHO periodicity and lower correlation coefficients and slopes. Moreover, body mass is uncorrelated, and brain size and activity levels are more strongly correlated with HHO periodicity in these animals. We argue that lemurs evolved this pattern due to selection for risk-averse life histories driven by the unpredictability of the environment in Madagascar. These results reinforce the idea that HHO influences life history evolution differently in response to specific ecological selection regimes.
Department of Rehabilitation Sciences, Florida Gulf Coast University, Fort Myers, Florida, United States of America.
Russell T
RT
Hogg
Department of Anthropology, University of Massachusetts at Amherst, Amherst, Massachusetts, United States of America.
Laurie R
LR
Godfrey
Institute of Human Origins and School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, United States of America.
Gary T
GT
Schwartz
Department of Anthropology, Durham University, Durham, United Kingdom.
Wendy
W
Dirks
Department of Biomaterials and Biomimetics, and Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York, United States of America.
Timothy G
TG
Bromage
D000818:Animals; D005075:Biological Evolution; D007900:Lemur / Q000033:anatomy & histology / Q000502:physiology*; D015233:Models, Statistical