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Lizard Females That Look Like Males Are Less Attractive (to Male Lizards)

The views expressed are those of the author and are not necessarily those of Scientific American.


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In many species, male and females look different to each other. In these ‘sexually dimorphic’ species, males tend to be more ornamented. ‘Ornaments’ are basically anything that’s just for decoration with no other function, the classic example being the peacock’s tail.

I have never mistaken a peacock for a peahen

 

Male deer also have ornaments: their antlers

Female and male humans are sexually dimorphic, but a lot less so than some other animals (I have often mistaken a women for a man, or a man for a woman, but I have never mistaken a peacock for a peahen).

 

 

 

In some animals, females occasionally show rudimentary forms of male traits (the particular ornament of that species). An example in humans of a female showing a male trait would  be male-pattern facial hair (i.e. beards).

So-called ‘bearded ladies’ have had a tough history, with the strong social stigma associated with having male-typical facial hair. Between the 15th and 19th centuries they were even paraded in front of audiences in circus ‘freak shows’.

A poster of Annie Jones, who suffered from hypertrichosis

As science progressed and as people learned more about how such previously mysterious anomalies arose, so society started to treat those who looked different to themselves less as ‘freaks’ and more as other human beings. Interestingly, freak shows apparently do still exist, but their proponents now put a different spin on it (see here to read about ‘Black Scorpion

Male fence lizards are bright blue on their throat and on the sides of their body. A recent study has looked at how male lizards respond to female lizards that show a rudimentary version of this trait.  They found that the male lizards discriminated against these females, choosing not to mate with them. The ornamented females (that I actually think look a lot prettier) reproduced less than the non-ornamented ones. They also produced eggs that hatched later, possibly because it took them longer to find a male to mate with.

The fence lizard Sceloporus undulatus: a)male; b) ornamented female; and c) regular female

Why might female ornamentation still exist in this species, if it is so detrimental? It is possible that ornamented females have some advantages outside of reproduction, for example being more socially dominant. It is also possible that these females produce better quality male offspring (with more or better ornamentation). However, the scientists did not find that the ornamented females produced more males than the non-ornamented ones, as you might expect if this were the case.

A male fence lizard

It is worth bearing in mind that this is just one species. In other species, such as some species of birds, ornamented females are actually more fecund compared to non-ornamented females. And of course, this says nothing about human ‘ornamentation’. At a fancy-dress party I was told that I was actually rather fetching with a moustache, and no one can deny that Johnny Depp looks good in makeup.

 

 

 

 

Photo Credits

Peacock & hen: Darkros

Deer: Caroline Granycome

Annie Jones: Poster, author unknown

Fence lizards: Lindsey Swierk and Courtney Norjen

Male fence lizard: Jarek Tuszynski

 

Reference

Swierk L, Langkilde T. 2013 Bearded ladies: females suffer fitness consequenceswhen bearing male traits. Biol Lett 9:20130644.

Felicity Muth About the Author: Felicity Muth is an early-career researcher with a PhD in animal cognition. Follow on Twitter @notbadscience.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. N a g n o s t i c 1:07 am 11/14/2013

    You think blue-ornamented female fence lizards look prettier? Obviously, you’re not a male fence lizard, as well as not a typical human being, see how you “often” mistake women for men and vice-versa. Regarding the last paragraph, I’m going to guess human females with mustaches and human males with a fondness for make-up, regardless of peer compliments received, will be less fecund than males w/mustaches and females wearing makeup. It’s just a hunch.

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  2. 2. N a g n o s t i c 1:11 am 11/14/2013

    Oh, the horrors – “seeing how…” in the second sentence would’ve been a little better.

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  3. 3. kendall5 8:15 am 11/14/2013

    It’s possible the males of the species need a sharp differentiation between male and female bodies in order to recognize the bio sex of any particular body.

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  4. 4. Felicity Muth in reply to Felicity Muth 6:30 pm 11/15/2013

    Yes- I’d say one likely reason for the discrimination against females with male-typical traits is just the males not recognising the females as female as easily

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