View previous topic | View next topic

Peacocks

Page 1 of 2
Goto page 1, 2  Next

Frederick The Monk
308744.  Wed Apr 02, 2008 5:21 am Reply with quote

How do peahens chose a mate? Not by looking for the one with the best tail feathers......



Notes:Was Darwin wrong about the sexual allure of the peacock's tail? A controversial study has found no evidence for the traditional view practically enshrined in evolutionary lore that peahens choose their partners depending on the quality of the peacocks' tails.

Mariko Takahashi and Toshikazu Hasegawa at the University of Tokyo in Japan studied peacocks and peahens in Izu Cactus Park, Shizuoka, from 1995 to 2001.

They judged tail quality in two ways first by simply measuring tail length, and secondly by taking photos of each male during the tail-fanning display ritual and counting the number of eyespots. Next they examined whether females chose mates with the best-quality tails.

During the seven years of observation, Takahashi's team observed 268 successful matings. But surprisingly, they found that females mated with poor-quality peacocks as often as with "flashy", high-quality males.
They conclude that the peacock's train is not the object of female sexual preference contradicting Darwin's theory of sexual selection.

Takahashi points out that growth of the peacock's train is dependent on the absence of oestrogen rather than the presence of testosterone. She says this undermines the assumption that the train is a sexual signal.
"Until now, who cared that the peacock's train was under oestrogen control?" Takahashi says.


Sources: Journal Reference: Animal Behaviour (DOI: 10.1016/j.anbehav.2007.10.004

 
eggshaped
308749.  Wed Apr 02, 2008 5:26 am Reply with quote

**physically restrains Dr.Bob**

Link to the fact that what we call a peacock's tail is actually its train.

post 172508

In fact, this could be nice. We could do the train/tail thing, and then ask Fred's question. With forfeits for tail AND train.

 
eggshaped
308752.  Wed Apr 02, 2008 5:28 am Reply with quote

Picture researchers, can we find a pic of a peacock with a particularly grand looking train and a particularly rubbish looking tail?

 
dr.bob
308813.  Wed Apr 02, 2008 5:59 am Reply with quote

Frederick The Monk wrote:
They judged tail quality in two ways first by simply measuring tail length, and secondly by taking photos of each male during the tail-fanning display ritual and counting the number of eyespots. Next they examined whether females chose mates with the best-quality tails.

During the seven years of observation, Takahashi's team observed 268 successful matings. But surprisingly, they found that females mated with poor-quality peacocks as often as with "flashy", high-quality males.


Surely all they've managed to do there is prove that peahens aren't swayed by either total length of the train (so size isn't important, after all) or number of eyespots. They may still be making choices based on the train, just examining some other quality of it.

 
WB
308839.  Wed Apr 02, 2008 6:13 am Reply with quote

Frederick The Monk wrote:
But surprisingly, they found that females mated with poor-quality peacocks as often as with "flashy"


Great quote

 
MatC
308852.  Wed Apr 02, 2008 6:19 am Reply with quote

Quite; it sounds as if the researchers are measuring the qualities of the train that are significant to human eyes, not knowing which qualities are significant to peacocks. Did Darwin suggest which qualities of the train were significant? If he said length, or number of eyes, then the question is a legit debunking at least of that specific point.

 
Flash
308972.  Wed Apr 02, 2008 7:28 am Reply with quote

To be fair, though, this objection (that we don't know what qualities the peahen admires in a train) must presumably be addressed in the full version of their paper unless they're completely incapable. The quote about oestrogen vs testosterone hints at a careful piece of research which has been misrepresented by being reduced to a soundbite.

 
Flash
308982.  Wed Apr 02, 2008 7:36 am Reply with quote

This is a good question in a number of ways, one of which is that it lets us make the point about it being a train rather than a tail without hanging the whole question on that essentially footling (sorry) bit of pedantry.

 
Flash
308985.  Wed Apr 02, 2008 7:42 am Reply with quote

Maybe:
What's the best way to impress a pea-hen?

F: Show her your tail (wrong on two grounds)

But ... what's the correct answer? Did they figure that out?

 
dr.bob
309083.  Wed Apr 02, 2008 9:25 am Reply with quote

Flash wrote:
it lets us make the point about it being a train rather than a tail without hanging the whole question on that essentially footling (sorry) bit of pedantry.


No need to apologise. I'm well known for my footling pedantry :)

I'll have a dig around for the original article and see if there was anything more to the selection process than arbitrarily deciding what peahens are interested in.

 
Flash
309095.  Wed Apr 02, 2008 9:44 am Reply with quote

The study took them seven years, so you would certainly hope so.

Bob, if you do find that article it would be good to know the 'answer' to the question, ie what are the hens looking for if not the train? Also, if it's not for sexual selection then what is it for?

 
Frederick The Monk
309610.  Thu Apr 03, 2008 4:54 am Reply with quote

The problem with the result is that I don't think they came up with an alternative - it was simply a negative result, which is no bad thing, but it doesn't allow us to answer the question as to what turns peahens on.

 
eggshaped
309622.  Thu Apr 03, 2008 5:04 am Reply with quote

Forfeit for "A peacock's cock"

 
dr.bob
310677.  Fri Apr 04, 2008 11:02 am Reply with quote

I found the article's abstract here, though it's obviously too new for the entire article to be generally available.

The abstract notes that they studied symmetry of arrangement of the tail as well as length and number of eyes. They also note that, while:

Quote:
the peacock's train (1) is not the universal target of female choice, (2) shows small variance among males across populations, and (3) base on current physiological knowledge, does not appear to reliably reflect the male condition


they observed that:

Quote:
the male train and its direct display towards females seem necessary for successful reproduction


so I guess it must be useful for something, even if it's not the sole deciding factor.

 
Flash
310682.  Fri Apr 04, 2008 11:07 am Reply with quote

A bit unsatisfactory. And it was all going so well.

 

Page 1 of 2
Goto page 1, 2  Next

All times are GMT - 5 Hours


Display posts from previous:   

Search Search Forums

Powered by phpBB © 2001, 2002 phpBB Group