Thursday, September 30, 2010

Phalacrocorax auritus

I am attempting to semi-triumphantly return to the world of actually posting on my blog. But of course the frustrations of photography tend to get in the way. I need to make time to actually go shoot and then when I do I realize after looking at the images that my camera was set on all the wrong settings. O well, some of them are actually passable.

So I spent some time trying to identify exactly which cormorant species this is and I think it is the double-crested, so named because during the breeding season the males grow long white tufty "crests" on their faces. That's sexual selection for you. It'll favor just about any weird morphological change if it aptly correlates with fitness. Even weird grandpa eyebrows.

Sexual selection is the freakish step-sister of natural selection. Instead of the selection being imposed by the environment it is imposed by (usually) female mate choice. So with natural selection features are generally selected for that make the organism better at surviving. Being better at surviving will in turn increase the number of offspring you have because if you die you can't have offspring. Alternately, sexual selection increases the number of offspring you have because if no one wants to mate with're sad. Plus, no offspring.

Sexual selection is sometimes dubbed "runaway" sexual selection when it does REALLY crazy things: like the peacock tail. This is the classic example of runaway sexual selection. Their tails are actually a hindrance to survival because the sheer weight of them severely decreases their ability to escape from predators. And the peacock's range is occupied by one of the world's most efficient land predators: the tiger. Solely due to the peahen's preference for more ridiculous tail plumage the peacock has continued to evolve larger and larger tails. Researchers have actually studied this by gluing false "eye spots," the round markings found on peacock tails, and found a direct correlation between the number of eye spots and female mate choice. So its an evolutionary "choice" between not getting eaten by a tiger or not mating. Poor peacocks.

But I digress: I've always been attracted to cormorants because they can often be seen out of water sunning themselves. The reason they do this is because they lack the special oil glands that ducks, geese and most water birds have to keep water from soaking their feathers. So they have to dry themselves the old fashioned way.

Though they're not my best shots I did enjoy seeing this one because it has three species and they're all chordates! The cormorants, Canadian geese as well as some species of turtles in the bottom right. Pretty cool.

Futuyma, Douglas J. (1998). Evolutionary Biology 3rd Edition. Sunderland, MA: Sinauer Associates, Inc.

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