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Titolo:
OPTIMAL MATING STRATEGIES IN NONTERRITORIAL UNGULATES - A GENERAL-MODEL TESTED ON MUSKOXEN
Autore:
FORCHHAMMER MC; BOOMSMA JJ;
Indirizzi:
UNIV OSLO,DEPT BIOL,DIV ZOOL,POB 1050 N-0316 OSLO NORWAY UNIV AARHUS,DEPT ECOL & GENET DK-8000 AARHUS C DENMARK
Titolo Testata:
Behavioral ecology
fascicolo: 2, volume: 9, anno: 1998,
pagine: 136 - 143
SICI:
1045-2249(1998)9:2<136:OMSINU>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
NORTHEAST GREENLAND; FORAGING DYNAMICS; SPERM COMPETITION; OVIBOS-MOSCHATUS; SYSTEMS; BEHAVIOR; MAMMALS; ECOLOGY; POPULATION; EVOLUTION;
Keywords:
FEMALE DISTRIBUTION; MUSKOX; NONTERRITORIAL UNGULATES; OPERATIONAL SEX RATIO; OPTIMAL MATING STRATEGIES; OVIBOS MOSCHATUS; SEXUAL SELECTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
58
Recensione:
Indirizzi per estratti:
Citazione:
M.C. Forchhammer e J.J. Boomsma, "OPTIMAL MATING STRATEGIES IN NONTERRITORIAL UNGULATES - A GENERAL-MODEL TESTED ON MUSKOXEN", Behavioral ecology, 9(2), 1998, pp. 136-143

Abstract

We present a marginal value model explaining intraspecific and interspecific variation of mating systems in nonterritorial ungulates. The model takes into account the simultaneous effects of spatial and temporal distribution of females, female group size, male-male competition, female choice, and the operational sex ratio (i.e., the proportion of estrous females). The model predicts that higher numbers of females per group increases the average exploitation time of such groups by males. An increase in female group density, operational sex ratio, and age-specific fighting success of males are predicted to reduce the average exploitation time of female groups, leading to roving of males (i.e., moving between female groups). In contrast, an increase in the female rejection rate of males and in the time spent by males on nonmating activities (i.e., foraging, lying down, ruminating, migrating) are predicted to increase the average exploitation time of female groups and to favor staying behavior of males (i.e., defending a female group over a longer period of time). Consequently, the model predicts that young males will tend to be ''stayers,'' whereas middle-aged and old malesare expected to be ''rovers. '' Model predictions were tested with field data collected on muskoxen Ovibos moschatus in a natural populationin west Greenland. Observed correlations between bull exploitation times of cow groups and the six above-mentioned social and environmentalparameters were all in the predicted direction and statistically significant in five of the six cases. Overall, 69% of the observed variation in exploitation time of cow groups by males was explained by the model predictions. Stepwise regression suggested that, of the six parameters, variation in sex ratio (R-2 = .56) and time spent on nonmating activities (R-2 = .35) had the largest effects on male exploitation time. Also, the observed age-specific variation in bull exploitation timeof cow groups was as predicted.

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Documento generato il 20/09/20 alle ore 19:29:12