Navigation Links
Pressured by predators, lizards see rapid shift in natural selection

Countering the widespread view of evolution as a process played out over the course of eons, evolutionary biologists have shown that natural selection can turn on a dime -- within months -- as a population's needs change. In a study of island lizards exposed to a new predator, the scientists found that natural selection dramatically changed direction over a very short time, within a single generation, favoring first longer and then shorter hind legs.

The findings, by Jonathan B. Losos of Harvard University and colleagues, are detailed this week in the journal Science. Losos did much of the work before joining Harvard earlier this year from Washington University in St. Louis.

"Because of its epochal scope, evolutionary biology is often caricatured as incompatible with controlled experimentation," says Losos, professor of organismic and evolutionary biology in Harvard's Faculty of Arts and Sciences and curator in herpetology at the Harvard Museum of Comparative Zoology. "Recent work has shown, however, that evolutionary biology can be studied on short time scales and that predictions about it can be tested experimentally. We predicted, and then demonstrated, a reversal in the direction of natural selection acting on limb length in a population of lizards."

Losos and colleagues studied populations of the lizard Anolis sagrei on minuscule islands, or cays, in the Bahamas. They introduced to six of these cays a larger, predatory lizard (Leiocephalus carinatus) commonly found on nearby islands and known as a natural colonizer of small cays. The scientists kept six other control cays predator-free and exhaustively counted, marked, and measured lizards on all 12 isles.

Anolis sagrei spends much of its time on the ground, but previous research has shown that when a terrestrial predator is introduced, these lizards take to trees and shrubs, becoming increasingly arboreal over time. Losos and his colleagues hypothesized that immediately fol lowing a predator's arrival, longer-legged -- and hence faster-running -- Anolis lizards would be favored to elude capture. However, as the lizards grew ever more arboreal in habitat, the scientists projected that natural selection would begin to favor shorter limbs, which are better suited to navigating narrow branches and twigs.

Their hypothesis was borne out. Six months after the introduction of the predator, Losos found that the Anolis population had dropped by half or more on the islands with the predators, and in comparison to the lizards on the predator-free islands, long legs were more strongly favored: Survivors had longer legs relative to non-survivors. After another six months, during which time the Anolis lizards grew increasingly arboreal, selective pressures were exactly the opposite: Survivors were now characterized by having shorter legs on the experimental islands as compared to the control islands.

The behavioral shift from the ground to higher perches apparently caused this remarkable reversal, Losos says, adding that behavioral flexibility may often drive extremely rapid shifts in evolution.

"Evolutionary biology is by its nature an historical science, but the combination of microevolutionary experimentation and macroevolutionary historical analysis can provide a rich understanding about the genesis of biological diversity," the researchers write.
'"/>

Source:Harvard University


Related biology news :

1. Creeping crinoids! Sea lilies crawl to escape predators, new video shows
2. Nice guys do finish first in lizards evolutionary race
3. Global survey of lizards reveals greater abundance of animals on islands than on mainland ecosystems
4. Mouse brain cells rapidly recover after Alzheimers plaques are cleared
5. Researchers develop rapid diagnostic tool for pathogen identification
6. Variation in HIVs ability to disable host defenses contributes to rapid evolution
7. New technique rapidly detects illness-causing bacteria
8. NASA satellite data provides rapid analysis of Amazon deforestation
9. Prions rapidly remodel good protein into bad, Brown study shows
10. Customized gene chip provides rapid detection of genetic changes in childrens cancer
11. A bugs life: Exceptional genomic stability yet rapid protein evolution in a carpenter ant mutualist

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:4/28/2016)... Sweden , April 28, 2016 First ... M (139.9), up 966% compared with the first quarter of 2015 ... profit totaled SEK 589.1 M (loss: 18.8) and the operating margin ... 7.12 (loss: 0.32) Cash flow from operations was SEK ... The 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. ...
(Date:4/15/2016)... -- Research and Markets has announced the ...  report to their offering.  ,      ... gait biometrics market is expected to grow at ... Gait analysis generates multiple variables such ... compute factors that are not or cannot be ...
(Date:3/29/2016)... RATON, Florida , March 29, 2016 ... or the "Company") LegacyXChange "LEGX" and SelectaDNA/CSI Protect are ... DNA in ink used in a variety of writing ... theft. Buyers of originally created collectibles from athletes on ... through forensic analysis of the DNA. ...
Breaking Biology News(10 mins):
(Date:4/27/2016)... MD (PRWEB) , ... April 27, 2016 , ... ... Greg Lamka, PhD to its Scientific Advisory Board. Dr. Lamka will assist PathSensors ... plant pathogen detection. , PathSensors deploys the CANARY® test platform for the ...
(Date:4/27/2016)... PARIS , April 27, 2016 ... system disorders, today announces the appointment of Catherine Moukheibir as ... succeed MedDay,s previous Chairman, Jean Jacques Garaud , who ... The change is effective immediately. Catherine started her ... Boston and London .  She ...
(Date:4/26/2016)... ... April 26, 2016 , ... The European Patent Office (EPO) today ... three finalists for the European Inventor Award 2016 in the category "Non-European countries." The ... at a ceremony in Lisbon on June 9th. , The human capacity to walk ...
(Date:4/26/2016)... ... April 26, 2016 , ... BioFactura, Inc ., a ... round of financing. Healthy investor interest drove significant oversubscription of the original $1.5M ... known as biosimilars, to the advanced preclinical stages. , Chief Executive Officer and President, ...
Breaking Biology Technology: