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Predation, sex ratios, and male competition in equids (Mammalia: Perissodactyla)
Author(s) -
Berger Joel
Publication year - 1983
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1983.tb04270.x
Subject(s) - biology , equus , predation , predator , competition (biology) , equidae , zoology , equus asinus , donkey , ecology , sex ratio , intraspecific competition , demography , population , sociology
Existing data indicate that a greater preponderance of adult females rather than adult males occurs in most species of mammals. The hypothesis that such differences arise as a result of intermale reproductive competition for females (and not predation) was examined in the Equidae by comparing populations of horses ( Equus caballus ), asses ( E. asinus ), and two species of zebras ( E. zebra and E. burchelli) in predator‐free, predator‐rich and insular ecosystems. Evidence is presented that: (1) sex differences in adult mortality occur; (2) they relate to the type and intensity of natural predation; and (3) asymmetries in sex ratios are most often explicable in terms of intermale reproductive competition. Exceptions are discussed and they are complicated by numerous proximate factors.