Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The ‘classic’ Trivers–Willard fitness functions, for which the sex ratio version of the Trivers–Willard hypothesis holds, while the investment version does not. Because male fitness always increases faster with condition than does female fitness, fitness returns to investment in a male offspring are always greater than in a female offspring of the same initial condition, and so a mother with a mixed brood will always invest more in the male of the brood, no matter her own condition.
