a cost of maternal care in the dung beetle onthophagus taurus：在蜣螂屎壳郎成本产妇护理.pdf

A cost of maternal care in the dung beetle Onthophagus taurus ? J. HUNT,* L. W. SIMMONS* & J. S. KOTIAHO *Evolutionary Biology Research Group, Department of Zoology, University of Western Australia, Nedlands, Western Australia, Australia Department of Biological and Environmental Science, University of Jyva è skyla è, Jyva è skyla è, Finland Introduction Theoretical studies of life-history evolution are based on the assumption that trade-offs exist between important life-history variables (Williams, 1966; Gadgil & Bossert, 1970; Charnov & Krebs, 1974; Schaffer, 1974; Pianka & Parker, 1975; Charlesworth, 1980). The most prominent of these trade-offs involves the cost of reproduction, where an increase in current reproductive effort has a negative effect on future reproduction (Williams, 1966). Consequently, natural selection is unable to simulta- neously maximize reproductive effort over consecutive breeding attempts (Williams, 1966; Gadgil & Bossert, 1970; Schaffer, 1974; Charlesworth, 1980). Rather, parents are expected to optimize their reproductive ess from current and future reproduction by balan- cing the ?tness bene?ts of continued investment in current offspring against the resulting costs to future survival and/or fecundity (Williams, 1966). As ?tness is a product of lifetime reproductive performance, the trade- off between current and future reproduction has import-