Featured Research

from universities, journals, and other organizations

Worm Procreation: 50 Ways To Be Your Lover

Date:
April 4, 2006
Source:
University Of Maryland, College Park
Summary:
In a study published in the April 3 issue of Developmental Cell, University of Maryland biology professor Eric Haag shows with genetic analysis that, while the female sex of two very closely related nematodes both evolved from female ancestors to become hermaphrodites - both female and male in one, they did it in different ways.

A virgin adult C. briggsae hermaphrodite worm. The two oval spots in the middle are fertilized eggs beginning to develop. This worm carries a mutation in a gene called fem-3, which in C. elegans is essential for hermaphrodites to make sperm.
Credit: Photo Eric Haag

When it comes to love among worms, there's more than one way for a gal to leave her lover and still keep the worm population booming.

In a study published in the April 3 issue of Developmental Cell, University of Maryland biology professor Eric Haag shows with genetic analysis that, while the female sex of two very closely related nematodes both evolved from female ancestors to become hermaphrodites - both female and male in one, they did it in different ways.

"Both species we studied have the same trick of hermaphroditism," says Haag, "but the way they pull it off is different."

The finding is evidence, Haag says, that similar evolutionary innovations can be achieved in different ways. "It shows there is more than one way to skin a cat."

Family Ties

The nematodes Caenorhabditis elegans and briggsae are cousins in a common family of tiny bacteria-eating worm found in shallow soil and compost piles. Most individuals of both species have the quirky characteristic of being anatomically female animals that are also male just long enough to create offspring without mating.

On the outside, they look the same as non-hermaphroditic females, but inside, they are independent ladies. "The trick to being a hermaphrodite is having the ability to make sperm in the female body," says Haag. "They make eggs continuously as adults, like normal females. But as adolescents, their spermathecae (sperm storage pouches) fill with sperm that they use later to self-fertilize."

In both species, the hermaphrodite sex has two X chromosomes, like their female ancestors, "yet somehow, they can make sperm," says Haag. "It's as if they say 'Why don't we forget about being female for a while, make sperm and then we'll go back.'"

Neither of these species has always been so antisocial in their sex lives. At about the same time, both evolved a hermaphrodite sex from an ancestor that was a true female and needed to mate with a male to have offspring.

Evolutionary Poster Children

These species of nematodes make excellent subjects for evolutionary study, Haag says. For one thing, their DNA is similar in most ways, making the differences stand out. C. elegans also has the advantage of being a heavily studied creature, whose genome was the first of any animal to be sequenced.

Enter C. briggsae, the perfect comparison, Haag thought, occupying a close branch on the family tree, evolving the same adaptation from the same male/female ancestor, but a relative newcomer in genetic studies.

Starting in the 1970's, researchers began finding sex-reversing mutations in C. elegans. These mutations eventually revealed how the hermaphrodites manage to block female action, then turn it back on. Haag's team devised a way to recreate these same mutations in C. briggsae, the first studies to create such gender-bending mutants in the species.

"The results were surprisingly different from C. elegans," says Haag. "We found that these look-alike hermaphrodites accomplish the same trick of evolution in a different way. The molecular toggle switch that reverses the cell's sexual fate is in one place on the genetic pathway of the C. elegans and a different place in the C. briggsae."

It's Not Easy Being Hermaphrodite

"It seems intuitive that sex is better for variation." says Haag, "but continuing to have sex every generation puts a lot of pressure on a species. If you're an animal that colonizes new territory, it helps not to have to mate. It's such a good idea, you wonder why all the worms don't do it. They don't care for their offspring, so they don't need a mate to help in that process."

But, says Haag, "It's not easy to become a hermaphrodite. They have to invent the toggle switches and survive inbreeding depression."

Which, apparently, according to Haag, can be a problem. "Over the years, there have been numerous species of nematodes that have become hermaphrodites. They can survive for millions of years, but eventually they go extinct. Meanwhile, the old-school male/female species seem to stick around long-term."

The take-home lesson, Haag suggests, might be that "Even while it may seem appealing to ditch your mate, in the really long run, you just might wish you had kept them around."

The study was funded with grants from the University of Maryland and the National Science Foundation.


Story Source:

The above story is based on materials provided by University Of Maryland, College Park. Note: Materials may be edited for content and length.


Cite This Page:

University Of Maryland, College Park. "Worm Procreation: 50 Ways To Be Your Lover." ScienceDaily. ScienceDaily, 4 April 2006. <www.sciencedaily.com/releases/2006/04/060404092234.htm>.
University Of Maryland, College Park. (2006, April 4). Worm Procreation: 50 Ways To Be Your Lover. ScienceDaily. Retrieved April 25, 2014 from www.sciencedaily.com/releases/2006/04/060404092234.htm
University Of Maryland, College Park. "Worm Procreation: 50 Ways To Be Your Lover." ScienceDaily. www.sciencedaily.com/releases/2006/04/060404092234.htm (accessed April 25, 2014).

Share This



More Plants & Animals News

Friday, April 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Fungus Killing Bats, Spreading in US

Deadly Fungus Killing Bats, Spreading in US

AP (Apr. 24, 2014) A disease that has killed more than six million cave-dwelling bats in the United States is on the move and wildlife biologists are worried. White Nose Syndrome, discovered in New York in 2006, has now spread to 25 states. (April 24) Video provided by AP
Powered by NewsLook.com
Blood From World's Oldest Woman Suggests Life Limit

Blood From World's Oldest Woman Suggests Life Limit

Newsy (Apr. 24, 2014) Scientists say for the extremely elderly, their stem cells might reach a state of exhaustion. This could limit one's life span. Video provided by Newsy
Powered by NewsLook.com
Raw: Kangaroo Rescued from Swimming Pool

Raw: Kangaroo Rescued from Swimming Pool

AP (Apr. 24, 2014) A kangaroo was saved from drowning in a backyard suburban swimming pool in Australia's Victoria state on Thursday. Australian broadcaster Channel 7 showed footage of the kangaroo struggling to get out of the pool. (April 24) Video provided by AP
Powered by NewsLook.com
Could Marijuana Use Lead To Serious Heart Problems?

Could Marijuana Use Lead To Serious Heart Problems?

Newsy (Apr. 24, 2014) A new study says marijuana use could lead to serious heart-related complications. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins