Award Abstract #0237126
Collaborative Proposal: Dental Development and Life History of Malagasy Lemurs

NSF Org:	BCS Division of Behavioral and Cognitive Sciences
Initial Amendment Date:	April 8, 2003
Latest Amendment Date:	May 24, 2004
Award Number:	0237126
Award Instrument:	Continuing grant
Program Manager:	Mark L. Weiss BCS Division of Behavioral and Cognitive Sciences SBE Directorate for Social, Behavioral & Economic Sciences
Start Date:	April 15, 2003
Expires:	January 31, 2005 (Estimated)
Awarded Amount to Date:	$142999
Investigator(s):	Gary Schwartz garys.iho@asu.edu (Principal Investigator)
Sponsor:	Northern Illinois University 301 Lowden Hall De Kalb, IL 60115 815/753-1581
NSF Program(s):	PHYSICAL ANTHROPOLOGY
Field Application(s):
Program Reference Code(s):	OTHR,0000
Program Element Code(s):	1392

ABSTRACT

Ever since the pioneering work of Adolf Schultz, primatologists have shown a sustained interest in the skeletal developmental correlates of life history variation among primates, and in their implications for understanding the evolution of life history. More recently, the fossil record has been the direct focus of such comparative work. New tools in dental microstructure are available for teasing out aspects of life history variation among extinct species and have begun to be applied with great success to subfossil lemurs. Teeth preserve within them a permanent record of their development enabling researchers to retrieve longitudinal developmental data from single adult specimens. This is not merely extremely useful for exploring life history variation among extinct species, but it promises to revolutionize our understanding of some aspects of the life histories of extant species as well.

Scientific merit: This study will bring the study of dental microstructure and other new analytical tools to bear on one of the most fascinating groups of extinct primates: the giant subfossil lemurs of Madagascar. Their closest living relatives, the extant lemurs, show remarkable variation in the timing of dental, craniofacial, and somatic growth and development, all within the context of a highly seasonal and unpredictable environments. These differing patterns of dental and skeletal growth relate to variation in lemur life history strategies - in particular, to the trade-off between adult female survival and reproductive effort. By combining data on the behavioral ontogeny of food processing (using new techniques in use-wear analyses), dental development and eruption (via radiography), and dental microstructural analyses of single adult specimens, this project will address questions never before asked of extinct primates: How long was gestation in giant lemurs? How rapidly did they grow? At what age did weaning occur in these species, and how prolonged was the weaning transition? Do frugivorous lemur species grow more slowly than like-sized folivores, as predicted by the ecological risk aversion hypothesis? Does the seasonal scheduling of growth in extinct lemurs cause a large proportion of adult size to be achieved before weaning, or do fundamentally different rates of infant growth characterize extinct lemur taxa as they do extant lemurs? Finally, advances in landmark-based 3-D geometric morphometrics (e.g., Morphologika, HETPAD), along with conventional analysis of trait-age matrices to chronicle the relationships between dental, brain and craniofacial development in extinct lemurs, allows us to test current hypotheses regarding the evolution of life history strategies in what is perhaps the world's most unique and diverse adaptive radiation of primates. Ultimately, this study will provide the evolutionary developmental framework for understanding the evolution of life history variation in primates.

Broader impact: An important broader impact of this study is graduate and postgraduate training. One of the PIs has a Malagasy graduate student who is studying lemurs and has expressed an interest in learning the techniques described here. The microstructural work required here will also provide ideal training for a two-year postdoctoral associate. Furthermore, the PIs have ongoing collaborations with others in the realms of Madagascar's paleobiology, lemur ecology, ecomorphology, heterochrony and skeletal ontogeny, and dental microstructure. We expect the work described here to intersect profitably with other research projects, and thus to inform research on the evolution of primate community structure in Madagascar, the patterns and causes of extinction, and the evolutionary developmental biology of primates.

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