BY FRANCISCO J. AYALA
Department of Ecology and
Evolutionary Biology
University of California, Irvine
Irvine, Calif.
" Male threespine sticklebacks exhibit a red nuptial coloration on the throat that functions to attract females and intimidate rival males. The red nuptial trait does not occur in some populations, a phenomenon that has been attributed to selection by salmonid predators. However, there is no corre,lation between nuptial-color loss and presence or absence of predators. Rather, expression of pigment occurs most frequently in habitats with the highest water clarity and is generally absent in heavily stainedwaters. This may occur as a result of signal masking; an alternative explanation is that it results from the sticklebacks’ carotenoid-deficient diets in murky waters.
T.E. Reimchen of nuptial color in threespine sticklebacks (Gasterosteus aculeatus),” Evolution, 43,450-60, March 1989; University of Alberta, Edmonton)
" The nests of Eciton burchelli army ants contain some 500,000 individuals. On most days, ...
