Featured Research

from universities, journals, and other organizations

Flies May Reveal Evolutionary Step To Live Birth

Date:
November 25, 2008
Source:
University of California, San Diego
Summary:
A species of fruit fly from the Seychelles Islands often lays larvae instead of eggs, biologists have discovered. Clues to how animals switch from laying eggs to live birth may be found in the well-studied species' ecology and genes.

On the verge: Drosophila yakuba sometimes lays eggs that have already hatched. Its genome may help to reveal how animals make the switch to live birth.
Credit: Drosophila Species Stock Center

A species of fruit fly from the Seychelles Islands often lays larvae instead of eggs, UC San Diego biologists have discovered. Clues to how animals switch from laying eggs to live birth may be found in the well-studied species’ ecology and genes.

The fly is one of a dozen species of Drosophila to have recently had their genomes sequenced, information that should provide abundant opportunities for identifying genetic changes that cause females of this species, and not others, to retain their fertilized eggs until they are ready to hatch.

The result was so surprising that the scientists initially thought it was a mistake.

“The student who was timing things came a said ‘wow, these eggs in this species really develop quickly,’ sometimes in less than an hour. That’s not possible,” said Therese Markow, a professor of biology who led the project. “When I went and actually looked at them I saw that they were depositing something that was very advanced, that hatched into a larva right away. In several cases they were hatching as they were being laid.”

Even those Seychelles fly eggs that emerged unhatched were at an advanced state of development, the team reports in forthcoming issue of the Journal of Evolutionary Biology. Most larvae emerged within two hours compared to an average of nearly 23 hours for the other 10 species in the study.

The Seychelles flies also laid larger eggs -- nearly double the average volumes found for the other species -- and their ovaries have fewer threadlike structures called ovarioles in which insect eggs mature before fertilization.

Live birth could result from changes to the male reproductive strategy as well. Proteins found in the semen of the well-known lab fruit fly, Drosophila melanogaster, stimulate egg laying in the female. A modification of these signals could be responsible for the switch.

“That signaling mechanism between the male and the female has changed. We don’t know the basis for it, but we ought to be looking,” Markow said. “It’s very interesting. It tells you who’s really going to be able control reproduction.”

Early hatching offers advantages, the authors say. Mobile larvae can burrow into the ground to avoid becoming inadvertent hosts to the eggs of parasitic insects or a predator’s meal. But harboring offspring for a longer period of time costs the female.

The opportunity to take that risk may come with specialization. The Seychelles flies feed only on the fruit of the morinda tree, a tropical plant that produces year round, but is toxic to other fruit flies, giving this single species exclusive access.

One other fly in the study, Drosophila yakuba, also occasionally laid larvae instead of eggs, and their eggs also hatched fairly quickly, most in under 14 hours. It too specializes in a particular fruit, that of the Pandanus tree.

The Seychelles flies, Drosophila sechellia and D. yakuba are two of about 250 species held by the Drosophila Species Stock Center, which moved to UC San Diego this fall.


Story Source:

The above story is based on materials provided by University of California, San Diego. Note: Materials may be edited for content and length.


Journal Reference:

  1. T. A. Markow, S. Beall, L. M. Matzkin. Egg size, embryonic development time and ovoviviparity in Drosophila species. Journal of Evolutionary Biology, 2008; DOI: 10.1111/j.1420-9101.2008.01649.x

Cite This Page:

University of California, San Diego. "Flies May Reveal Evolutionary Step To Live Birth." ScienceDaily. ScienceDaily, 25 November 2008. <www.sciencedaily.com/releases/2008/11/081123222848.htm>.
University of California, San Diego. (2008, November 25). Flies May Reveal Evolutionary Step To Live Birth. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2008/11/081123222848.htm
University of California, San Diego. "Flies May Reveal Evolutionary Step To Live Birth." ScienceDaily. www.sciencedaily.com/releases/2008/11/081123222848.htm (accessed July 24, 2014).

Share This




More Plants & Animals News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. 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