Summary
Demographic data relating to herd size and stability are given for a population of Cape mountain zebra (Equus zebra zebra) under longterm observation. Temporal dispersion patterns of male and female offspring differed and were independent of the mother's status. Dispersion in females appeared to be related to physiological state, and dispersion in both sexes was related to age rather than changes in parental behaviour. Reproductive success of dominant and subordinate mares was equal and independent of age and social and reproductive variables. Fitness of dominant mares, however, was significantly higher than that of subordinates, the latter having a higher foal mortality, part of which could be attributable to dominants' aggression. The fitness of all males born was 1.6:1 compared with all females. Dominant mares produced significantly more daughters than sons. This trend was not found for subordinates. Mother's status was positively correlated with dominant status in her female offspring but not related to the subsequent status of her sons. Daughters had a more than twice as great a chance of breeding than sons. For maximum fitness gains, therefore, dominant mares should produce more daughters, since a high proportion of these would also have high status and fitness. This tendency is reflected in the sex ratio skewed towards females found for dominant mares.
Similar content being viewed by others
References
Altmann J (1980) Baboon mothers and infants. Harvard University Press. Cambridge, Mass.
Berger J (1977) Organizational systems and dominance in feral horses in the Grand Canyon. Behav Ecol Sociobiol 2:131–146
Clutton-Brock TH, Guinness FE, Albon SD (1982) Red deer: the behaviour and ecology of two sexes. Chicago University Press, Chicago
Clutton-Brock TH, Albon SD, Guiness FE (1984) Maternal dominance, breeding success and birth ratios in red deer. Nature 308:358–360
Dunbar RIM (1984) Reproductive decision: an economic analysis of gelada baboon social strategies. Princeton University Press, Princeton, New Jersey
Feist JD, McCullough DR (1975) Reproduction in feral horses. J Reprod Fert, Suppl 23:13–18
Goodall J (1968) The behaviour of free-living chimpanzees in the Gombe Stream Reserve. Anim Behav Monogr 1:165–301
Hausfater G (1975) Dominance and reproduction in baboons (Papio cynocephalus): a quantitative analysis. Contrib Primatol 7:1–150
Hausfater G, Altmann J, Altmann S (1982) Long-term consistency of dominance relations among female baboons (Papio cynocephalus). Science 217:752–755
Hrdy SB (1977) The Langurs of Abu. Harvard University Press, Cambridge Mass
Joubert E (1971) Ecology, behaviour and population dynamics of the Hartmann Zebra Equus zebra hartmannae (Matschie 1898) in South West Africa. Ph.D. Thesis, Univ Pretoria
Kawai M (1958) On the system of social ranks in a natural troop of Japanese monkeys. I Basic and dependent rank. Primates 14:113–159
Klingel H (1967) Soziale Organization und Verhaltensweisen von Hartmann-und Bergzebras (Equus zebra hartmannae und E. z. zebra). Z Tierpsychol 25:76–88
Klingel H (1969a) Reproduction in the plains zebra Equus burchelli boehmi: behaviour and ecological factors. J Reprod Fert, Suppl 6:339–345
Klingel H (1969b) Dauerhafte Sozialverbande beim Bergzebra. Z. Tierpsychol 26:965–966
Maynard Smith J (1980) A new theory of sexual investment. Behav Ecol Sociobiol 7:247–251
Miller R (1979) Band organization and stability in Red Desert feral horses. In: Denniston RH (ed) Proc Conf Ecol Behav Feral Equids. University of Wyoming Press, Laramie, pp 113–123
Missakian EA (1972) Genealogical and cross-genealogical dominance relations in a group of free-ranging rhesus monkeys (Macaca mulatta) on Cayo Santiago. Primates 13:169–180
Penzhorn BL (1984) A long-term study of social organization and behaviour of Cape mountain zebra Equus zebra zebra. Z Tierpsychol 64:97–146
Sherman PW (1980) The limits of ground squirrel nepotism. In: Barlow G, Silverberg J (eds) Sociobiology: beyond nature/nurture? Westview Press, Boulder, Colorado, pp 505–544
Silk JB (1983) Local resource competition and facultative adjustment of sex ratios in relation to competitive abilities. Am Nat 121:56–66
Simpson MJ, Simpson AE (1983) Birth sex ratios and social rank in rhesus monkey mothers. Nature 300:440–441
Trivers RL (1971) The evolution of reciprocal altruism. Q Rev Biol 46:35–57
Trivers RL (1972) Parental investment and sexual selection. In: Campbell B (ed) Sexual selection and the descent of man. Aldine-Atherton Press, Chicago, pp 136–179
Trivers RL, Willard DE (1973) Natural selection of parental ability to vary the sex ratio of offspring. Science 179:90–92
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lloyd, P.H., Rasa, O.A.E. Status, reproductive success and fitness in Cape mountain zebra (Equus zebra zebra). Behav Ecol Sociobiol 25, 411–420 (1989). https://doi.org/10.1007/BF00300187
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00300187