Sex Ratios and Age Ratios in North American Ducks

Sex ratios.

Jennions et al. introduce the different kinds of sex ratio and their biology.

Bayesian reconstruction of two‐sex populations by age: estimating sex ratios at birth and sex ratios of mortality

The original version of Bayesian reconstruction, a method for estimating age-specific fertility, mortality, migration and population counts of the recent past with uncertainty, produced estimates for female-only populations. Here we show how two-sex populations can be similarly reconstructed and probabilistic estimates of various sex ratio quantities obtained. We demonstrate the method by recon...

Distorting sex ratios.

D uring sperm production in mammals, the process of meiosis generates sper-matozoa that are genetically different but functionally equivalent. So, with respect to the sex chromosomes, for example, equal numbers of sperm are produced carrying either an X or a Y chromosome. Because X and Y sperm are equally capable of fertilizing an egg, equal numbers of male and female embryos are produced, and ...

Sex ratios in primate groups

Changing sex ratios in diabetes.

A survey of sexes and ages in patients attending the Hartlepool diabetic clinic was carried out for the 20-year period 1948-67. The proportion of men aged 50 and over rose from 25.9% in the first decade to 38.2% in the second. An attempt has been made to explain this pronounced and rapid change.