![]() ![]() They found this pressure, called the selection gradient, declines with maternal age. To address this, Hernández and collaborators built mathematical models to calculate, for the first time, the strength of natural selection pressure on the survival and fertility of offspring populations as functions of the age of their mothers. So why do we see this phenomenon across so many species?" "Natural selection should weed out these less-fit offspring of older mothers. "This study is unique in that it combines laboratory data from our prior work with mathematical modeling to address a longstanding question in the evolution of aging," Gribble says. ![]() The study, led by Kristin Gribble of the Marine Biological Laboratory and Christina Hernández of Woods Hole Oceanographic Institution, is published this week in Proceedings of the National Academy of Sciences. They also suggest an evolutionary mechanism for why this may occur. They confirmed that this effect of older maternal age, called maternal effect senescence, does reduce evolutionary fitness of the offspring in all environments, primarily through reduced fertility during their peak reproductive period. In a new study in rotifers (microscopic invertebrates), scientists tested the evolutionary fitness of older-mother offspring in several real and simulated environments, including the relative luxury of laboratory culture, under threat of predation in the wild, or with reduced food supply. ![]()
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