Featured Research

from universities, journals, and other organizations

Ancestor of snakes, lizards likely gave birth to live young

Date:
December 17, 2013
Source:
George Washington University
Summary:
The ancestor of snakes and lizards likely gave birth to live young, rather than laid eggs, and over time species have switched back and forth in their preferred reproductive mode, according to new research.

Alex Pyron is the Robert F. Griggs Assistant Professor of Biology in the Columbian College of Arts and Sciences at the George Washington University.
Credit: The George Washington University

The ancestor of snakes and lizards likely gave birth to live young, rather than laid eggs, and over time species have switched back and forth in their preferred reproductive mode, according to research published in print in Ecology Letters Dec. 17.

"This is a very unusual and controversial finding, and a major overturn of an accepted school of thought," said Alex Pyron, Robert F. Griggs Assistant Professor of Biology in the Columbian College of Arts and Sciences at the George Washington University. "Before, researchers long assumed that the ancestor of snakes and lizards laid eggs, and that if a species switched to live birth, it never reverted back. We found this wasn't the case."

The findings push researchers' understanding of the evolution of live birth a lot further back in time to 175 million years ago, showing that live birth has a much more ancient past as a strategy than previously believed. The findings are backed by several recent plesiosaur and mosasaur fossil discoveries and the fossil record of a few lizards from the Cretaceous Period, which had embryos in the mother and had live birth.

Dr. Pyron analyzed an evolutionary tree containing all groups of squamates -- the group that comprises lizards and snakes -- which he and a team of researchers published in the journal BMC Evolutionary Biology earlier this year. The tree, which uses DNA sequencing technology to group thousands of lizards and snakes, includes all families and subfamilies and most genus and species groups.

In total, about 115 groups of lizards and snakes, or about 2,000 species, have live birth. The other 8,000 species lay eggs -- at least right now.

Dr. Pyron is working next to analyze all tetrapods -- a group composed of animals with four legs, such as amphibians, reptiles, birds, mammals and turtles -- to see if there are any new surprises about the evolution of their reproductive modes. He also wants to test the genetics at work behind the evolutionary switching of reproductive mode.


Story Source:

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


Journal Reference:

  1. R. Alexander Pyron, Frank T. Burbrink. Early origin of viviparity and multiple reversions to oviparity in squamate reptiles. Ecology Letters, 2013; DOI: 10.1111/ele.12168

Cite This Page:

George Washington University. "Ancestor of snakes, lizards likely gave birth to live young." ScienceDaily. ScienceDaily, 17 December 2013. <www.sciencedaily.com/releases/2013/12/131217084926.htm>.
George Washington University. (2013, December 17). Ancestor of snakes, lizards likely gave birth to live young. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2013/12/131217084926.htm
George Washington University. "Ancestor of snakes, lizards likely gave birth to live young." ScienceDaily. www.sciencedaily.com/releases/2013/12/131217084926.htm (accessed September 16, 2014).

Share This



More Plants & Animals News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
Lion Cubs the Pride of San Diego Zoo

Lion Cubs the Pride of San Diego Zoo

Reuters - US Online Video (Sep. 13, 2014) Roars of excitement as a proud lioness shows off her four cubs at the San Diego Zoo Safari Park. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
'Magic Mushrooms' Could Help Smokers Quit

'Magic Mushrooms' Could Help Smokers Quit

Newsy (Sep. 11, 2014) In a small study, researchers found that the majority of long-time smokers quit after taking psilocybin pills and undergoing therapy sessions. 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