Featured Research

from universities, journals, and other organizations

Two Rapidly Evolving Genes Offer Geneticists Clues To Why Hybrids Are Sterile Or Do Not Survive

Date:
November 30, 2006
Source:
Cornell University
Summary:
While hybrids -- the result of the mating of two different species -- may offer interesting and beneficial traits, they are usually sterile or unable to survive. For example, a mule, the result of the mating of a horse and a donkey, is sterile. Now, Cornell researchers have made the first identification of a pair of genes in any species that are responsible for problems unique to hybrids.

Drosophila melanogaster, left, and D. simulans.
Credit: Photo Daniel Barbash

While hybrids -- the result of the mating of two different species -- may offer interesting and beneficial traits, they are usually sterile or unable to survive. For example, a mule, the result of the mating of a horse and a donkey, is sterile.

Now, Cornell researchers have made the first identification of a pair of genes in any species that are responsible for problems unique to hybrids. Specifically, the researchers have found two genes from two fruit fly species (Drosophila melanogaster and D. simulans) that interfere with each other, thereby preventing the production of male offspring.

The finding may eventually shed light on what causes lethality or sterility in hybrids in general and, in a larger sense, offers clues to how species evolve from common ancestors.

The research, published in the Nov. 24 issue of Science, focuses on a rarely occurring mutation in a D. melanogaster gene called "Hmr" (Hybrid male rescue) and a similar mutation in a D. simulans gene called "Lhr" (Lethal hybrid rescue) that make these genes nonfunctional. When either of these genes is "turned off" and then crossed with the other fruit fly species, the males survive.

"We have found the first example of two genes that interact to cause lethality in a species hybrid," said the paper's senior author, Daniel Barbash, assistant professor in Cornell's Department of Molecular Biology and Genetics.

The finding supports the Dobzhansky-Muller model, a theory from the 1930s that suggests hybrid incompatibilities (such as death or sterility) are caused by genes that have evolved from a common ancestor but diverged in each of the species. More specifically, in the common ancestor, these genes may have worked perfectly well together. But, as each gene evolved in its own species, it began to code for proteins that no longer work in the other species.

In this case, when genes from each species were compared with each other, the Hmr gene in D. melanogaster and the Lhr gene in D. simulans each evolved much faster than most other genes and diverged due to natural selection, a genetic change due to a pressure that benefits the survival of a species. The researchers would like to learn what these genes normally do within their species in order to understand why they are evolving so fast.

The Dobzhansky-Muller model also proposes that these evolved genes depend on each other to cause hybrid incompatibilities.

However, when Barbash and his colleagues cloned each gene and inserted an Lhr gene from D. simulans into D. melanogaster, the two genes did not interfere with each other in the engineered D. melanogaster strain even though the Lhr and Hmr genes interfere with each other in hybrids.

"This tells us there must be other things involved in the hybrid" that impacts the incompatible pairing of these genes, said Barbash. In future work the researchers hope to determine whether the hybrids die because of additional genes like Hmr and Lhr, or because of more subtle differences between the chromosomes of these two species.

The study was funded by the National Institutes of Health.


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "Two Rapidly Evolving Genes Offer Geneticists Clues To Why Hybrids Are Sterile Or Do Not Survive." ScienceDaily. ScienceDaily, 30 November 2006. <www.sciencedaily.com/releases/2006/11/061129150811.htm>.
Cornell University. (2006, November 30). Two Rapidly Evolving Genes Offer Geneticists Clues To Why Hybrids Are Sterile Or Do Not Survive. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2006/11/061129150811.htm
Cornell University. "Two Rapidly Evolving Genes Offer Geneticists Clues To Why Hybrids Are Sterile Or Do Not Survive." ScienceDaily. www.sciencedaily.com/releases/2006/11/061129150811.htm (accessed April 24, 2014).

Share This



More Plants & Animals News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Monkeys Are Better At Math Than We Thought, Study Shows

Monkeys Are Better At Math Than We Thought, Study Shows

Newsy (Apr. 23, 2014) A Harvard University study suggests monkeys can use symbols to perform basic math calculations. Video provided by Newsy
Powered by NewsLook.com
Raw: Leopard Bites Man in India

Raw: Leopard Bites Man in India

AP (Apr. 22, 2014) A leopard caused panic in the city of Chandrapur on Monday when it sprung from the roof of a house and charged at rescue workers. (April 22) Video provided by AP
Powered by NewsLook.com
Iowa College Finds Beauty in Bulldogs

Iowa College Finds Beauty in Bulldogs

AP (Apr. 22, 2014) Drake University hosts 35th annual Beautiful Bulldog Contest. (April 21) Video provided by AP
Powered by NewsLook.com
805-Pound Shark Caught Off The Coast Of Florida

805-Pound Shark Caught Off The Coast Of Florida

Newsy (Apr. 22, 2014) One Florida fisherman caught a 805-pound shark off the coast of Florida earlier this month. 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