Journal ArticleDOI
Demographic and life history variables of a population of gelada baboons (theropithecus gelada)
TLDR
The population was found to be increasing at a fairly steady rate of about 120 per annum, and females within reproductive units were in close reproductive synchrony, partly due to the environmental control of conceptions; however, social factors also played an important role in bringing females into synchrony.Abstract:
SUMMARY (1) Demographic parameters of a free-ranging population of gelada baboons were determined during a field study in Ethiopia. (2) The annual birth rate varied inversely with the severity of the rainfall around the period of conception. The distribution of births within the year, however, was timed so as to minimize the exposure of the neonates to the severe wet season conditions. (3) Females within reproductive units were in close reproductive synchrony, partly due to the environmental control of conceptions; however, social factors also played an important role in bringing females into synchrony. (4) After the first year of life, mortality fell most heavily on the oldest age classes; exposure to severe wet season conditions, old age and parasitic infestations were the main causes of death. Age-specific mortality and fecundity rates were estimated. (5) The population was found to be increasing at a fairly steady rate of about 120 per annum. Migration by entire sub-sections of the population at aperiodic intervals helped to maintain the actual density of animals within the study area around a longterm mean value.read more
Citations
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Reproductive Effort and Terminal Investment in Iteroparous Animals
TL;DR: Though the long-lived birds and mammals are among the most promising organisms on which to test the theory that reproductive effort increases with age, measures of fecundity commonly decline with increasing maternal age, some recent evidence suggests that offspring survival may improve toward the end of the lifespan.
Journal ArticleDOI
Sexual dimorphism, the operational sex ratio, and the intensity of male competition in polygynous primates
TL;DR: A weight-corrected measure of sexual dimorphism and a biologically realistic assay of mating competition, the operational sex ratio, are employed to reexamine the factors favoring the evolution of sexual sizeDimorphism in primates and produce results consistent with the sexual selection hypothesis.
Journal ArticleDOI
Life History of Hamadryas Baboons" Physical Development, Infant Mortality, Reproductive Parameters and Family Relationships
TL;DR: Age-related changes in body weight and dentition were found to be delayed relative to laboratory-reared baboons, and females lost by one male to several rivals tended to reassemble in the same new one-male units later on.
Journal ArticleDOI
The relative importance of life-history variables to population growth rate in mammals: Cole's prediction revisited.
Madan K. Oli,F. Stephen Dobson +1 more
TL;DR: In this paper, the relative importance of life history variables to population growth rate (λ) has substantial consequences for the study of life-history evolution and for the dynamics of biological populations.
Journal ArticleDOI
Demography and social organization of free-ranging Lemur catta in the Beza Mahafaly Reserve, Madagascar
TL;DR: Demographic patterns in the demography of Lemur catta in southern Madagascar are discussed and related to patterns in other populations of ringtailed lemurs as well as in anthropoids.
References
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Journal ArticleDOI
The timing of birds‘ breeding seasons
TL;DR: There is a strong tendency for those young which are hatched earliest in the season to have the greatest chance of surviving to breed, and not all species are likely to be prevented, by food shortage, from breeding at the best time for raising young.
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Menstrual cycles: fatness as a determinant of minimum weight for height necessary for their maintenance or onset.
Rose E. Frisch,Janet W. McArthur +1 more
TL;DR: The data suggest that a minimum level of stored, easily mobilized energy is necessary for ovulation and menstrual cycles in the human female.
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Mortality Patterns in Mammals
TL;DR: The hypotheses that most mammalian species have life tables of a common form, and that the pattern of age—specific mortality within species assumes an approximately constant form irrespective of the proximate causes of mortality, are suggested.