As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Tuesday, 1 July 2014

Promiscuous males die young, childless females live longer

30 minutes ago by Vicky Just

(Phys.org) —A study of birds by researchers from our Department of Biology & Biochemsitry in collaboration with the University of Sheffield shows for the first time how sexual behaviour is linked with life expectancy and can cause an imbalance in sex ratios.

The research could be used to predict the causes and effects of unbalanced sex ratios in human populations.

The team of scientists have previously shown that the adult sex ratio (ASR, the ratio of males to females) affects mating behaviour in terms of mate choice, divorce rates, infidelity and promiscuity, and also determines the parenting roles of males and females.

In a new study, published in the journal Proceedings of the Royal Society B, the team looked at what causes an imbalance in the ratio between the sexes. They analysed data from 187 bird species to see whether sex ratios at birth, termed 'hatching sex ratios', or sex ratios at independence of the young, termed 'fledgling sex ratios', correlate with the ASR. Instead they found that difference in mortality of adult males and females was by far the most significant predictor for ASR. The study established that the unbalanced adult sex ratios were due to the biased death rates of adult males and females, rather than biased sex ratios of offspring.




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