Male lions with long, dark manes are more attractive to females and more intimidating to rivals, US research involving dummy animals shows.
The finding should help resolve the long-standing question of the function of lions鈥� manes, say researchers Peyton West and Craig Packer at the University of Minnesota.
鈥淭his is mind-blowing stuff,鈥� says zoologist Tim Birkhead at Sheffield University. 鈥淚t鈥檚 a very exciting contribution to the study of sexual selection,鈥� he told 快猫短视频.
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Manes vary from light blond to black and can be up to foot long. The team planted pairs of life-sized toy lions with different types of mane near males and females in the Serengeti National Park in Tanzania, and monitored the lions reactions to the 鈥榠ntruders鈥�. In all cases, males preferred to approach dummies with lighter, less shaggy manes.
Even then, they were extremely cautious, with each step taking twenty seconds or more. 鈥淲e had to invent a new term 鈥� pussyfooting 鈥� to describe their behaviour,鈥� says Peyton.
But females did the opposite. They preferred to approach darker males, suggesting they are a better bet as a mate.
High testosterone
Next, West and Packer examined data on blood samples from several dozen males that had been sedated. They found a strong correlation between blood testosterone levels and mane colour.
鈥淒ark colour tends to be found in high-testosterone males,鈥� West says. 鈥淭herefore, it isn鈥檛 surprising that females would prefer darker manes and males would be intimidated. But there is no correlation between testosterone and mane length. We figure males are sensitive to an opponent鈥檚 mane length because recently injured lions have shorter manes.鈥�
The pair also re-examined Pakcer鈥檚 own research dating back to the 1960s and found evidence that dark-maned males are better able to defend their family. One-year-old cubs of darker- maned fathers are less likely to be injured and more likely to survive until they are two.
Hot-blooded
Having a large dark mane does appear to be a burden, the team point out. Dark-maned animals are hotter than blond animals, presumably because dark hairs are thicker and trap more heat, the team says.
This is important because heat hampers sperm production in the testicles. Indeed, the study re-analysis revealed a great proportion of sperm from dark-maned males are abnormal. If only the best males can afford to put up with the costs associated with it, a dark mane should be a true indicator of quality.
Birkhead is particularly impressed that the researchers put together several lines of evidence to support their case. 鈥淚t really underlines the value of long-term research,鈥� he says. Journal reference: Science (vol 297, p 1339)