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Tight energetic constraints on reproductively active females are hypothesized to be a n important determinant of the phenomenon of female dominance in Propithecus uerreauxi, a primate endemic to Madagascar. Five wild sifakas were captured in the Beza Mahafaly Special Reserve in southern Madagascar, and resting metabolic rates (RMR) were measured. Levels were low, as predicted, with the exception of a possibly pregnant female. Although the data were not conclusive, they were consistent with the hypothesis.Key words: Madagascar, lemur, dominance, metabolic rate, Propithecus verreazmi, sifaka INTRODU@TIONSocial dominance of females over males is rare among mammals [Ralls, 1976; Hrdy, 19811, yet females are dominant in many, and perhaps all, of the primates of Madagascar [Pollock, 1979a;Jolly, 1984; Richard, in press]. Most dominance interactions among lemurs occur in the context of feeding, where females consistently supplant males [Jolly, 1966; Pollock, 197913; Richard, 19781. Hrdy [ 1981 J tentatively attributes the social dominance of female lemurs to a male strategy of deferring to females in order to conserve energy for the brief, but energetically costly, annual mating season. Conversely, Jolly [ 19841 suggests that it arises from seasonal stresses experienced by the females themselves. She argues that lemur young are altricial and, like other altricial mammals, have a high growth rate that imposes a heavy energy demand on the mother. However, there are currently few physiological measurements of mammalian energy expenditure during reproduction to test these ideas.In this paper preliminary data are presented on the metabolic rates of sifakas, Propithecus verreauxi (Indriidae), and we propose a modified version of Jolly's idea that high energy requirements imposed on reproductively active females are an important determinant of the phenomenon of female social dominance in the sifaka.Our model contains three predictions. These are, first, that basal metabolic rates (BMR) are characteristically low in sifakas; second, that sifaka females elevate

Traditionally, the fact that reproduction in eutherian (= placental) mammals tends towards prolonged intrauterine development and short lactation has been interpreted as an evolutionary advance over the metatherian (= marsupial) short gestation and prolonged lactation. However, it has recently been postulated that marsupial reproduction involves low initial energy investment and may be advantageous by minimizing energy loss if conditions necessitate early termination. Moreover, because marsupials have basal metabolic rates (BMRs) 30% lower than those of most eutherians, it has been suggested that daily and total energy expenditures during reproduction may also be lower. We have now tested the predictions that low BMR is maintained during reproduction and that initial investment is lower in marsupials. Using indirect calorimetry, we have made the first longitudinal measurements of energy expenditure during reproduction for a marsupial and for two eutherian species with low BMRs. We find that initial investment is lowest in a eutherian and total energetic expenditures were greatest for the marsupial. We also find that, relative to BMR, all three species have increased mean maternal resting metabolic rates (RMRs) during both gestation and lactation; this is the first evidence that mammals with low BMRs can substantially elevate metabolism for prolonged periods during gestation and lactation.

The present distribution of Coleura seychellensis and its roost sites are described, together with observations on roosting behaviour. Parturition occurred each November/December throughout the three‐year study period and coincided with one of the two annual rainfall peaks. The occurrence of young in April during the third year of observation suggests the possibility of polyoestry. Evidence for the decline in abundance of this species is presented and discussed.

Reproduction in female tenrecs was studied on Praslin Island (4 degrees 20'S, 55 degrees 45'E) in the Seychelles from November 1977 to September 1980. Dissection and histological examination of reproductive tracts revealed that each ovary is encapsulated in a bursa. Polyovular follicles were abundant and contained up to 5 oocytes. The occurrence of more implanted fetuses than corpora lutea (CL) indicated successful polyovuly in 25% of pregnancies. No antrum was observed during follicular growth at oestrus, and follicles were relatively small at maturation, reaching a maximum diameter of 570 microns. Ovulation involves a gentle extrusion of the granulosa and ovum into the periovarian space. Spermatozoa were abundant in the female reproductive tract including the periovarian space at oestrus. Spermatozoa penetrated the loosely-packed theca of mature follicles and were present in CL, indicating that intrafollicular fertilization may occur. The relatively small CL formed by eversion, reaching a maximum size after implantation. Fusion of up to four CL occurred in the ovaries of 41% of pregnant females. Polyovulation in the tenrec was confirmed by the occurrence of 10.4 +/- 0.5 (mean +/- s.e.m.) CL and 9.7 +/- 0.5 (mean +/- s.e.m.) implantations. Resorption occurred in 74% of 19 dissectable pregnancies, occurring in both uterine horns in 26% of pregnancies. Coefficients of variation in weights of fetuses in each litter were 10.0-26.8%, with the largest value corresponding to 273% variation in fetus weights. Litter size in the Seychelles tenrecs was smaller than in the same species in Madagascar (17.1 +/- 1.9 implantations) where the tenrec is native.

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