منابع مشابه
Natural Selection: Sex Ratio
Natural selection acts strongly on the proportional numbers of male and female offspring among the progeny of adults. The equilibrium is often one at which males and females are produced in roughly equal numbers, but under certain ecological and genetic circumstances there may be dramatic population-wide biases, and even in populations with balanced sex ratios, parents are often selected to pro...
متن کاملSex ratio, sex change, and natural selection.
We describe the analogy between the theory of natural selection on sex ratio in newborn gonochores (which will not change sex), and on the age of sex change in sequential hermaphrodites (which are all born into one sex and change to the other later on). We also discuss the conditions under which natural selection favors sequential hermaphrodites over gonochores and vice versa. We show that, in ...
متن کاملSex Ratio Elasticity Influences the Selection of Sex Ratio Strategy
There are three sex ratio strategies (SRS) in nature-male-biased sex ratio, female-biased sex ratio and, equal sex ratio. It was R. A. Fisher who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton's local mate competition (LMC) and Clark's local resource competition (LRC) separately explained the observed deviations from the seemingly u...
متن کاملNatural variation in the human sex ratio.
Analysis of the effect of multiple birth, birth order, age of parents and the sexes of preceding siblings on the secondary sex ratio was performed for 815 891 children, born in Denmark, 1980-1993. The proportion of males was analysed as a function of multiple birth, birth order, age of parents and the sexes of preceding siblings, using contingency tables, chi(2) tests and logistic regression an...
متن کاملNatural selection of parental ability to vary the sex ratio of offspring.
Theory and data suggest that a male in good condition at the end of the period of parental investment is expected to outreproduce a sister in similar condition, while she is expected to outreproduce him if both are in poor condition. Accordingly, natural selection should favor parental ability to adjust the sex ratio of offspring produced according to parental ability to invest. Data from mamma...
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ژورنال
عنوان ژورنال: Nature
سال: 1997
ISSN: 0028-0836,1476-4687
DOI: 10.1038/39718