A Tale of Two Manes

Explanation: This week we are still in east Africa, still viewing big cats on the savanna. But this week we have a lesson in what happens when populations become isolated.

Take a look again at the two lions in the above photos. What's different about them? And, more importantly ecologically, why?

They are both mature males ... but the one on top -- from Masai Mara, Kena -- seems to be sporting a much fuller mane ... whereas the one on bottom -- from Nogorongoro Crater, Tanzania, just to the south -- seems to have missed out from being so well equipped, and has essentially a mohawk-style spiky mane. But why?

Ngorongoro Crater in northern Tanzania is pretty much an isolated ecosystem, but male lions there probably had as full a mane as anywhere else in east Africa. So why are they so much shorter?

One hypothesis is that hunters chose male lions with the fullest manes as symbols of the greatest hunting conquest, so that, over time, the lions remaining were genetically predispositioned to sire only short-maned male cubs. Further, the isolated nature of the Crater meant that, with a small breeding population, lions may have suffered some additional negative effects from a certain degree of inbreeding.

What function do manes serve? There is some uncertainty about this. The manes of male lions serves as a signal of individual strength and sexual potency. This was Charles Darwin's concept of sexual selection, whereby females select males showing greater signals in specific anatomical features, such as the extreme plumes of birds of paradise, extensive antler racks of elk, or ... the otherwise rather nonfunctional manes of lions. Secondarily, manes can help the male appear larger and more intimidating to rivals and competitors, or may serve as a buffer against physical attacks.

But all is not lost. In warmer climates, lion manes appear shorter and are more adaptive. If there will continue to be regional climate warming in the lion's range, a shorter mane may be very adaptive and allow the lion to be pre-adaptive to environmental changes yet to come.

EPOW - Ecology Picture of the Week