Males have more predictable personalities
23 November 2009, by Sara Coelho
Males have more predictable personalities and that's exactly how females like them. Females are more variable, but new research suggests that they prefer mates with consistent behaviour, especially if they need to coordinate efforts to raise their young.
Females play an active role in the evolution of many species because they can choose their mates from a pool of potential partners and are able to select for features that they consider attractive. These might be signs of dominance, such as the deer's antlers, or extravagant displays of beauty like the peacock's tail.
But females are on the lookout for more than superficial looks.
'In a sense, females seem more sensible, because they adapt their behaviour according to the circumstances.'
Dr Sasha Dall,
University of Exeter
'This research suggests that male personality could have evolved in much the same way as physical attractiveness - to help attract a mate,' says lead author Dr Sasha Dall, a behavioural ecologist at the University of Exeter.
Just like humans, animals of the same species can have different personalities: some may be more adventurous or aggressive, while others tend to be shy or inconspicuous. Together with PhD student Wiebke Schütt, Dall looked at zebra finches to test how such personality differences may range between sexes.
The team focused on risk behaviour and encouraged individual finches to explore a novel environment. They took the birds' readiness to move between the features of the new cage (such as feeders or perches) as a measure of boldness.
'Some of the finches were very keen to approach the new things, others were more shy,' reports Dall.
Dall and Schütt found that although the males were not on average any more or less adventurous than females, they behaved more consistently from test to test. Shy males remained timid, whereas bold finches were always daring. Individual females, on the other hand, varied their behaviour more.
'Males have a more predictable behaviour,' says Dall. But reacting all the time the same way may be risky, or sometimes outright daft. If a finch is always audacious he may end up as sparrow-hawk's dinner; if he's always careful he will struggle to find enough food.
'In a sense, females seem more sensible, because they adapt their behaviour according to the circumstances,' adds Dall. Females are probably the culprits for the males' steady personalities - and sometimes inadequate responses - as they are likely to favour consistent males.
Dall says this idea still needs work, but he suggests that 'females prefer predictable males because it's easier to coordinate parenting efforts with partners with consistent personalities.'
In their recent scan of research reports, published in Biological Reviews, Dall and Schütt suggest that females of other species of birds and fish share this dislike for surprises and preference for predictable males.
But females might be on the look out for something else. Being consistent can be a very bad idea for birds living in an ever changing natural environment. So if a male survives to adulthood with an inefficient lifestyle, 'it's probably because he has good genes to compensate for that,' suggests Dall. And good genes are something that all females want from their mates.
Wiebke Schuett, Tom Tregenza, Sasha R. X. Dall. Sexual selection and animal personality. Biological Reviews, published online: Nov 18 2009. DOI: 10.1111/j.1469-185X.2009.00101.x
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