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Among yesterday's search terms:

underdog speed of lightning
thylacinus cynocephalus cladogram
bat penises
boys kissing
evolution cute mickey mouse

The one looking for bat penises was disappointed, as the search led instead to a reference to spider penises. But I can understand the interest, which was surely scientific:

Genitalia are conspicuously variable, even in closely related taxa that are otherwise morphologically very similar. Explaining genital diversity is a longstanding problem that is attracting renewed interest from evolutionary biologists.

(Hosken DJ & Stockley. 2004. Sexual selection and genital evolution. PDF)

If evolution is viewed narrowly as adaptation to environment, then sexual selection becomes something of a special case. The peacock's tail is the classic example, evolved as a result of competitive reproductive success, even though it is achieved at a cost to fitness otherwise.

In another case of "does size matter?," Hosken, et.al., investigate: Is the bat's penis sexually selected? and present evidence that it is not (PDF).

Another paper did find that sexual selection led to bigger bats' balls, although at a cost to brain size. There's not much to go around if you are a bat - so much is devoted to adaptation for flight - so big balls means a smaller brain. Interestingly, the Hosken, et. al. paper cited above did show a correlation between penis size and testis size, so I guess the jury's still out. Or you'll have to ask a scientist, or a bat.

So there.






(Blogger is acting squirrelier than usual today)