How being different boosts life expectancy

13 May, 2009, 11:45

A study has revealed that predators tend to avoid prey that look different from the rest of the population, which helps rare traits survive.

A team of biologists led by Benjamin Fitzpatrick from the University of Tennessee used dummy salamanders filled with feed with either striped or not striped skin to study the behavior of a flock of Blue Jays. The proportion of the two kinds of ‘prey’ was nine-to-one, and the scientists maintained the supply for six days in a row. The choice of the prevalent kind of prey was different in each case.

Then on test day they changed the proportion to one-to-one. The birds were more likely to attack the models, which were more common during the previous period. As it turned out, the actual skin pattern was irrelevant, only the rarity of the coloring in the days before the test day.

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"We believe that the different color forms represent different ways of blending in on the forest floor. Looking for something cryptic takes both concentration and practice. Predators concentrating on finding striped salamanders might not notice unstriped ones," Fitzpatrick believes.

The study published in BMC Ecology magazine gives an example of how variation may give an advantage and keep a population from blending into one single easy-to-hunt form.