Leaping Lizards and Male Impersonators: Are There Hidden Messages? by Imitating Male Mating Behavior, All-Female Lizard Species Apparently Enhance Their Own Ability to Reproduce

By Edwards, Diane D. | Science News, May 30, 1987 | Go to article overview

Leaping Lizards and Male Impersonators: Are There Hidden Messages? by Imitating Male Mating Behavior, All-Female Lizard Species Apparently Enhance Their Own Ability to Reproduce


Edwards, Diane D., Science News


Leaping Lizards and Male Impersonators: Are There Hidden Messages?

What do dandelions and certainspecies of fish have in common? There's not a male among them --yet they do very well, thank you. As one of several procreation options available in nature, all-female species are intriguing. But can this extreme form of asexual independence teach anything about the evolution of sexual behavior in higher animals, including Homo sapiens? Maybe, maybe not, say scientists who study lizards lacking the true male touch.

For most, life without the male of thespecies would lack a certain joi de vivre. The same might be said of a female-free world, with an added technicality: Life itself would be in shorter supply. While females and their eggs are crucial in species with sex differentiation, males can be superfluous in those that rely at least in part on the process called parthenogenesis, in which egg cells develop into individuals without fertilization.

Some species can alternate betweenparthenogenesis and sexual reproduction, depending on environmental conditions. Others stay true to parthenogenesis and its production of identical daughters--which, biologists point out, is a far more efficient way to reproduce than by sexual means, in which two cells are required for reproduction instead of one.

Giving a twist to the tale ofparthenogenesis, David Crews in 1979 reported a type of male impersonation among parthenogenetic whiptail lizards of the genus Cnemidophorus (SN: 12/22&29/79, p.423). While at Harvard University, he found that captive members of the all-female C. uniparens imitated mounting and mating postures of the male C. tigris, a Cnemidophorus species containing both males and females that reproduce sexually (see photos). Crews, now at the University of Texas in Austin, and his co-workers have since described this pseudosexual behavior in captive lizards from four other parthenogenetic whiptail species collected in the southwestern United States.

The lizards could change some oldtheories about sex, says Crews. He suggests that sexual behavior in animals may have evolved before the two sexes evolved. This may represent "a reversal of the old argument of first there was sex, then there was sexual behavior,' he says.

Although all are females, individualC. uniparens lizards are in a sense bisexual in their behavior, alternating their roles, says Crews. Which one plays the male in the aggressive pseudocopulatory event appears to be related to ovulation cycles, rather than size and age. The "male' of the pair either is past the point of ovulation (egg release) in its reproductive cycle, or its reproductive system is inactive. The preovulatory "female,' however, has large ovarian follicles and lays eggs about a month after the spurious mating dance.

Crews began searching for an explanationof the male-like behavior, which seems unnecessary in an all-female species capable of parthenogenesis--unless it actually serves some biological function. From observations made during a series of subsequent laboratory experiments, Crews concludes that pseudosexual behavior in C. uniparens does actually enhance the reproductive capability of the parthenogenetic lizard--a conclusion that has been met with some skepticism as well as interest.

Crews examined how productivity in C.uniparens is affected by such variables as male homrones and the presence or absence of different female cagemates. Similar studies in a parthenogenetic strain of fly were used for comparisons.

Data collected by the Texas group showthat, if C. uniparens are placed in isolation or with cagemates that have had their ovaries removed, the average number of egg batches (clutches) laid each breeding season drops to about 1, compared to an average of 1.5 clutches born to individuals housed with a cagemate having ovaries. But if a cagemate without ovaries is treated with the male hormone androgen --which causes male-like behavior in the lizards--the average number of clutches is comparable to the 2 to 3 clutches laid each season in a natural environment.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

Leaping Lizards and Male Impersonators: Are There Hidden Messages? by Imitating Male Mating Behavior, All-Female Lizard Species Apparently Enhance Their Own Ability to Reproduce
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.