Featured Research

from universities, journals, and other organizations

Sea Snails Break The Law

Date:
April 28, 2007
Source:
Smithsonian Tropical Research Institute
Summary:
Lizards gave rise to legless snakes. Cave fishes don't have eyeballs. In evolution, complicated structures often get lost. Dollo's Law states that complicated structures can't be re-evolved because the genes that code for them were lost or have mutated. A group of sea snails breaks Dollo's law, according to scientists.

Smaller males on top of larger females. The eggs are brooded under the shell and so are not visible.
Credit: Rachel Collin, STRI Staff Scientist

Lizards gave rise to legless snakes. Cave fishes don't have eyeballs. In evolution, complicated structures often get lost. Dollo's Law states that complicated structures can't be re-evolved because the genes that code for them were lost or have mutated. A group of sea snails breaks Dollo's law, Rachel Collin, Staff Scientist at the Smithsonian Tropical Research Institute and colleagues from two Chilean universities announce in the April, 2007, Biological Bulletin.

Related Articles


"This is important because it shows that animals may carry the potential for evolutionary change around with them. When the environment changes, new life forms may be able to regain abilities that were lost earlier in evolutionary history," Collin explains.

Most species of sea snail go through several life stages on the way to becoming reproductive adults. The early stages, or larvae, usually live in the water column eating microscopic algae and swimming with a specialized structure called the velum. This stage has been lost in many species, where development happens in immobile capsules protected by the mother. In these species, small bottom-dwelling juvenile snails (miniature adults) hatch out of eggs and crawl away. Thus, a whole life stage, the motile larva, is lost and thought to never been re-gained.

But how can you tell what happened in the past to bring this about? Collaborators from Chile, Argentina and the Smithsonian in Panama, using embryological observations and DNA sequencing, show that the larval stage can be reacquired.

The group collected 6 species of the genus Crepipatella from the shorelines of Argentina, Chile, Panama, Peru, South Africa and the United States. They observed the developmental stages of each species and sequenced a gene called mitochondrial cytochrome oxidase I. Then, based on the differences in gene sequences, they used several different techniques to reconstruct family trees.

Indeed, they found that motile, feeding larvae had been lost and re-gained in the same family group, which breaks Dollo's law. Collin sums this up: "The embryos of limpets in a group called Crepipatella seem to retain some of the apparatus they would need for larval feeding and swimming, even though they do not produce larvae. Then, from DNA data we see that one species with larvae has re-evolved in the middle of a group that doesn't have them. It does go both ways! There's more flexibility in animal evolution than people thought."

Reference: Rachel Collin, Oscar Chaparro, Federico Winkler, and David Velez. 2007. It goes both ways: evidence that feeding larvae have been regained in a marine gastropod. Biological Bulletin. April, 2007.


Story Source:

The above story is based on materials provided by Smithsonian Tropical Research Institute. Note: Materials may be edited for content and length.


Cite This Page:

Smithsonian Tropical Research Institute. "Sea Snails Break The Law." ScienceDaily. ScienceDaily, 28 April 2007. <www.sciencedaily.com/releases/2007/04/070424121820.htm>.
Smithsonian Tropical Research Institute. (2007, April 28). Sea Snails Break The Law. ScienceDaily. Retrieved March 30, 2015 from www.sciencedaily.com/releases/2007/04/070424121820.htm
Smithsonian Tropical Research Institute. "Sea Snails Break The Law." ScienceDaily. www.sciencedaily.com/releases/2007/04/070424121820.htm (accessed March 30, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Monday, March 30, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Lions Make Surprise Comeback in Gabon

Lions Make Surprise Comeback in Gabon

AFP (Mar. 30, 2015) Lions have made a comeback in southeast Gabon, after disappearing for years, according to live footage from US wildlife organisation Panthera. Duration: 00:32 Video provided by AFP
Powered by NewsLook.com
New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

Newsy (Mar. 29, 2015) A 508-million-year-old arthropod that swam in the Cambrian seas is thought to share a common ancestor with spiders and scorpions. Video provided by Newsy
Powered by NewsLook.com
Jaguar Cub Makes Adorable Debut in California

Jaguar Cub Makes Adorable Debut in California

Reuters - US Online Video (Mar. 29, 2015) The San Diego Zoo treats its guests to their newest family member -- a playful newborn jaguar cub. Gavino Garay reports. Video provided by Reuters
Powered by NewsLook.com
Vietnam Rice Boom Piles Pressure on Farmers and the Environment

Vietnam Rice Boom Piles Pressure on Farmers and the Environment

AFP (Mar. 29, 2015) Vietnam&apos;s drive to become the world&apos;s leading rice exporter is pushing farmers in the fertile Mekong Delta to the brink, say experts, with mounting costs to the environment. Duration: 02:35 Video provided by AFP
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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