Sentences with phrase «overall sex ratio»

Not exact matches

By observing groups of flour beetles in the laboratory, Melbourne and Alan Hastings, a mathematical ecologist at the University of California, Davis, demonstrated that random variations in sex ratios and physical differences, such as body size, greatly contribute to the overall threat of extinction.

The sex ratio in the overall population is «nothing out of the ordinary,» with roughly one juvenile male for every four juvenile females, says study coauthor Michael Jensen, a marine biologist with the National Oceanic and Atmospheric Administration in La Jolla, Calif..

Evolutionary biologists say male mortality, which is overall higher than that of females, explains the male bias in sex ratio: A slightly skewed sex ratio at birth that favors males ensures that there are roughly an equal number of males and females of reproductive age.