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Date of Graduation
Master of Science (MS)
Department of Biology
Despite living under the same environmental pressures and sympatrically in many cases, Propithecus verreauxi and Lemur catta have evolved very different strategies for survival in stochastic environmental conditions. P. verreauxi show slow somatic growth, low maternal investment, and rapid dental growth while L. catta show faster somatic growth, high maternal investment, and slower dental growth. P. v. coquereli are highly specialized for vertical clinging and leaping (VCL) among lemurs, while L. catta, the most terrestrial of lemurs, use a wider variety of locomotor types including quadrupedalism, climbing, and leaping. P. v. coquereli have unusually long legs and muscular thighs while L. catta have more similar limb lengths and muscular proximal limb segments (Lessertisseur and Jouffroy, 1973; Jouffroy, 1975). Little is known of the ontogenetic trajectories by which these adult forms are acquired. Because selection acts on the entire life cycle of an animal, it is important to investigate the morphological and locomotor changes occurring early in development. These changes might be important components to each species’ survival strategy that allow infant primates to travel with a group of larger adults and survive to adulthood. I examined changes in locomotor behavior and limb morphology from 0-2 years in L. catta and P. v. coquereli. Limb segment lengths, limb segment circumferences, and body mass were recorded every 2 weeks in infants and every 4 weeks in yearlings at the Duke Lemur Center (DLC). Locomotor data were collected on infants transitioning to locomotor independence and yearlings of each species in free-ranging enclosures at the DLC using locomotor bout sampling. Results indicate that both species are born with upper limb lengths similar to lower limb lengths, whereas only P. v. coquereli dissociates upper- and lower limb growth to reach adult limb proportions. P. v. coquereli transitional infants and yearlings use similar overall locomotor behavior and undergo rapid postcranial growth to achieve the limb proportions necessary for VCL by the time of locomotor independence. Relative to upper limb length, lower limb length is even longer in juveniles first leaping independently than in yearlings and adults. Relatively long hindlimbs may allow juveniles to achieve leaping take-off velocity similar to adults despite absolutely smaller size. L. catta transitional infants exhibit a different distribution of locomotor behavior than yearlings despite similarities in limb proportions. Much like P. v. coquereli juveniles are “ecological adults” in terms of their rapid dental development, they seem to also be “ecological adults” in terms of locomotor behavior. Because of the demand for using VCL at a young age, and despite overall slow postcranial growth, P. v. coquereli transitional infants are on a rapid growth trajectory towards achieving the limb proportions necessary for specialized leaping. Lowest IMI values at locomotor independence, increased leap frequency paired with decreased leap distance, and high positive allometric growth of the tail are three key findings that provide evidence as to how P. v. coquereli transitional infants are able to display similar locomotor repertoires as yearlings in order to keep up with the group to survive, despite being absolutely smaller.
Wolf, Stephanie Ann, "Ontogeny of postcranial morphology and locomotor behavior in Propithecus verreauxi coquereli and Lemur catta" (2011). Masters Theses, 2010-2019. 371.