Fetal Mortality and Sex Ratio

Brith Sex Ratio and Pregnancy Outcomes after Bam Earthquake

Background and Objectives: Brith sex ratio could be affected by several factors such as stress due to natural disasters like earthquake. This study was performed to determine the sex ratio and the perinatal outcomes after Bam earthquake. Materials and Methods: This case-control study was designed in two sections for the evaluation of earthquake effects on brith sex ratio and the perinatal outc...

Opposing effects of mortality factors on progeny operational sex ratio may thwart adaptive manipulation of primary sex ratio

Despite extensive research on mechanisms generating biases in sex ratios, the capacity of natural enemies to shift or further skew operational sex ratios following sex allocation and parental care remains largely unstudied in natural populations. Male cocoons of the sawfly Neodiprion abietis (Hymenoptera: Diprionidae) are consistently smaller than those of females, with very little overlap, and...

avicenna and obstetrics: fetal sex determination

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Sexuality: Sex Ratio and Sex Expression

Sex 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 ...