Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Rapid Samoan butterfly evolution

A parasite selectively killed males of a species of butterfly in Samoa. However resistance developed rapidly. Now numbers of males have sprung back to equal females. Some will say it's not evolution, simply adaptation to the environment. But what's the difference?

http://news.yahoo.com/s/nm/20070712/sc_nm/butterflies_dc

Can there be a difference? I wouldn't think so. It appears that those butterflies with the resistant physiology survived to propagate the useful trait. Result: overall, the species has changed, right? Looks like a good example of simple adaptive evolution.

Exactly. I doubt if we could hold it up as a great example of evolution in action.

Quite. Natural selection has been questioned even in the well known peppered moth example: http://www.talkreason.org/articles/mallet.cfm

I agree, there's a difference, I would think, between "Natural Selection" and "Evolution".

Here's something they don't say about this particular Butterfly - The little beggars are carnivorous! I'm an avid cyclist. You'll see a cloud of these things hovering over road-kill that's starting to decompose. As you get closer, you'll see that the cat, rat, whatever, is covered with these butterflies. Has anyone else here ever seen anything like that?

Wolfman. I've never seen butterflies behaving that way. Don't have many native butterflies here anyway. We get blue moon butterflies here very occasionally as migrants. I've never seen one here but have in OZ.

As to the change in blue moon and peppered moths being evolution. The new forms have always been present. It's just the ratios that changed. No new mutations were required. On the other hand it does show that the "normal" (take note Ellis) colour can change quite rapidly in wild species as well as domesticated species.

Terry, it's pretty gross, mate. You know, butterflies feed through a tube, a proboscis. These things go after small animals that have been dead awhile, starting to "liquify", if you know what I mean. I've never seen anything like it.

A lot of North American butterflies will deliberately feed on urine or "poop". They'll also go for water with a lot of minerals in it. This is known as puddling, and it helps them get certain minerals and nutrients.

http://en.wikipedia.org/wiki/Mud-puddling

This topic is rapidly approaching a yuck factor as big as the pig suckling incident. I think "normal" butterflies exist on nectar, honey and pretty things to do with scented blossom and lots of flowers as they flutter between them in the sunshine.

A great many "normal" butterflies do the puddling behavior! :-) Here's an extreme closeup shot I took myself of a butterfly that's common in Washington state puddling off of moist sand (nothing grotesque, I promise).

http://www.photomacrography2.net/forum/viewtopic.php?p=15395&highlight=#15395

The puddling behavior is strictly to get minerals, especially sodium, and you're right, nectar is a more conventional butterfly food!

"A great many "normal" butterflies do the puddling behavior!"

Yet another 'fairies and butterflies' fantasy bites the dust.
"Mummy, look at the beautiful butterfly"
"Yes, dear, but it eats poop."

Actually, because of some quirk in the link I used above, you have to scroll to the top of the linked page to see the butterfly shot. Y'all will figure it out!

Nice picture. I always wondered what butterflies were doing at mud puddles. I've also seen them on mineral blocks for cattle. I presume for the same purpose.

Back to the subject of blue moon butterflies. I suppose on reflection it is an example of evolution. The proportion of the population carrying the particular gene has changed. Ultimately I guess that's all evolution is. Anyway, MikeBinOK, impressive photo.

Same thing from Discovery news:

http://dsc.discovery.com/news/2007/07/12...=20070712160030

'It is not yet clear whether the suppressor gene emerged from a chance mutation from within the local population, or if it was introduced by migratory Southeast Asian butterflies in which the mutation had already been established.

"But regardless of which of the two sources of the suppressor gene is correct, natural selection is the next step. The suppressor gene allows infected females to produce males, these males will mate with many, many females and the suppressor gene will therefore be in more and more individuals over generations," Charlat explained.

Overall, the waxing and waning fortunes of the male Blue Moon butterfly shows that not only how fast species can evolve, or adapt, but just how important parasites can be as evolutionary drivers, the authors said.

"In the case of H. bolina, we're witnessing an evolutionary arms race between the parasite and the host. This strengthens the view that parasites can be major drivers in evolution," said Charlat.'