Relative growth of the limbs and trunk in sifakas: heterochronic, ecological, and functional considerations.
Abstract
Limb, trunk, and body weight measurements were obtained for growth series of Milne-Edwards's
diademed sifaka, Propithecus diadema edwardsi, and the golden-crowned sifaka, Propithecus
tattersalli. Similar measures were obtained also for primarily adults of two subspecies
of the western sifaka: Propithecus verreauxi coquereli, Coquerel's sifaka, and Propithecus
verreauxi verreauxi, Verreaux's sifaka. Ontogenetic series for the larger-bodied P.
d. edwardsi and the smaller-bodied P. tattersalli were compared to evaluate whether
species-level differences in body proportions result from the differential extension
of common patterns of relative growth. In bivariate plots, both subspecies of P. verreauxi
were included to examine whether these taxa also lie along a growth trajectory common
to all sifakas. Analyses of the data indicate that postcranial proportions for sifakas
are ontogenetically scaled, much as demonstrated previously with cranial dimensions
for all three species (Ravosa, 1992). As such, P. d. edwardsi apparently develops
larger overall size primarily by growing at a faster rate, but not for a longer duration
of time, than P. tattersalli and P. verreauxi; this is similar to results based on
cranial data. A consideration of Malagasy lemur ecology suggests that regional differences
in forage quality and resource availability have strongly influenced the evolutionary
development of body-size variation in sifakas. On one hand, the rainforest environment
of P. d. edwardsi imposes greater selective pressures for larger body size than the
dry-forest environment of P. tattersalli and P. v. coquereli, or the semi-arid climate
of P. v. verreauxi. On the other hand, as progressively smaller-bodied adult sifakas
are located in the east, west, and northwest, this apparently supports suggestions
that adult body size is set by dry-season constraints on food quality and distribution
(i.e., smaller taxa are located in more seasonal habitats such as the west and northeast).
Moreover, the fact that body-size differentiation occurs primarily via differences
in growth rate is also due apparently to differences in resource seasonality (and
juvenile mortality risk in turn) between the eastern rainforest and the more temperate
northeast and west. Most scaling coefficients for both arm and leg growth range from
slight negative allometry to slight positive allometry. Given the low intermembral
index for sifakas, which is also an adaptation for propulsive hindlimb-dominated jumping,
this suggests that differences in adult limb proportions are largely set prenatally
rather than being achieved via higher rates of postnatal hindlimb growth.(ABSTRACT
TRUNCATED AT 400 WORDS)
Type
Journal articleSubject
Adaptation, BiologicalAnalysis of Variance
Animals
Arm
Body Constitution
Body Height
Body Weight
Diet
Ecology
Female
Least-Squares Analysis
Leg
Madagascar
Male
Regression Analysis
Seasons
Sex Characteristics
Strepsirhini
Tropical Climate
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https://hdl.handle.net/10161/6407Published Version (Please cite this version)
10.1002/ajpa.1330920408Publication Info
Ravosa, MJ; Meyers, DM; & Glander, KE (1993). Relative growth of the limbs and trunk in sifakas: heterochronic, ecological, and
functional considerations. Am J Phys Anthropol, 92(4). pp. 499-520. 10.1002/ajpa.1330920408. Retrieved from https://hdl.handle.net/10161/6407.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Kenneth Earl Glander
Professor Emeritus of Evolutionary Anthropology
Primate ecology and social organization: the interaction between feeding patterns
and social structure; evolutionary development of optimal group size and composition;
factors affecting short and long-term demographic changes in stable groups; primate
use of regenerating forests.

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