( ted on opposite sides of a tank and re...)Older female fish prefer imperfect male mates, study finds

In previous research conducted elsewhere, females were shown to prefer symmetrical over asymmetrical males when presented with a choice. Scientists suggested that symmetrical figures have more redundant information, which makes for a more powerful, easy-to-remember stimulus. Females also may be likely to choose symmetrical males because they are better able to deal with environmental stresses and could pass on that resilience to offspring.

Another explanation would be that the visual system "develops an internal prototype of an object that is based on an average of all the male fish [the females] have seen," Morris said. "Therefore, any fish they see that is closest to this prototype is preferred." The same phenomenon has been suggested to explain attraction in other animals, including humans.

As their lives progress, however, female swordtails may encounter more asymmetrical than symmetrical males, and so begin to prefer the pattern to which they have become accustomed in their environment, she said.

Further research based on this study might examine whether the experience of mating draws older females to asymmetrical males, or whether there is a genetic factor, activated at a certain age or size, that makes larger females select more asymmetrically striped males.

The asymmetrical barring pattern is likely a result of environmental stresses experienced before birth, Morris explained. Some males have the genetic makeup to deal with these stresses and still develop a symmetrical pattern, while others survive the stress but show marks of the struggle. A population with a large amount of asymmetrical individuals may have been subject to a lot of environmental stress, suc
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Source:Ohio University