Featured Research

from universities, journals, and other organizations

Same adaptations evolve across different insects

Date:
July 24, 2012
Source:
Cornell University
Summary:
For years, scientists have questioned whether evolution is predictable, or whether chance events make such predictability unlikely. A new study finds that in the case of insects that developed resistance to a powerful plant toxin, the same adaptations have occurred independently, in separate species in different places and times.

Monarch butterfly caterpillar.
Credit: Ellen Woods

The famous biologist Stephen J. Gould once asked: If we rerun the tape of life, would the outcome of evolution be the same? For years, scientists have questioned whether evolution is predictable, or whether chance events make such predictability unlikely.

A study published online July 23 in the Proceedings of the National Academy of Sciences finds that in the case of insects that developed resistance to a powerful plant toxin, the same adaptations have occurred independently, in separate species in different places and times.

The paper examines 18 insect species across four orders -- beetles, butterflies and moths, flies, and true bugs -- that all feed on plants containing powerful toxins called cardenolides.

Common to milkweeds and foxglove, cardenolides are lethal to nearly all insects and function effectively as a defense against pests. Cardenolides work by binding to a cell's sodium pump, one of the most fundamental systems found in all animal cells. The sodium pump works when an essential enzyme (Na,K-ATPase) carries important elements, sodium and potassium, across the cell membrane. Cardenolides bind to the enzyme and disable it, thereby shutting down cells, which results in severe damage.

Among the 18 insects surveyed, the researchers found a few methods that the insects use to resist cardenolides. In monarch butterflies and a species of leaf beetle, for example, resistance is due to a specific mutation -- called N122H -- of the Na,K-ATPase gene. The mutation reduces cardenolide binding to the sodium pump enzyme.

"Already knowing how monarchs deal with the toxin, we wanted to see if it was the same molecular solution used by beetles, flies and true bugs that are also resistant to cardenolides," said Anurag Agrawal, a Cornell professor of ecology and evolutionary biology and a co-author on the paper. Susanne Dobler, a professor of molecular evolution at Hamburg University, is the paper's lead author.

By examining molecular changes in the sodium pump gene, the researchers found the mutation N122H in all four orders of insects studied. Furthermore, they discovered a second mutation in the same gene that also conferred resistance in 11 of the 18 species.

"This is truly a remarkable level of evolutionary repeatability and suggests that evolving resistance to the plant toxin had very few effective options," said Agrawal.

The researchers tested the effectiveness of these gene changes by inserting the single Na,K-ATPase mutations into cell cultures and then dosing those cultures with cardenolides. They found the mutations gave the cells resistance, and when cells were given the two mutations that repeatedly evolved together, they had twice the resistance as cells with a single mutation, implying a synergistic effect.

The standard gene for the sodium pump is essentially the same in all insects, and even mammals carry the gene in a relatively unmodified form. The sodium pump thus originated from a common ancestor hundreds of millions of years ago and is central to the functioning of most animals. Out of that background, insects from different orders over the last 300 million years specialized on plants with cardenolides and evolved resistance independently, and in numerous cases, through exactly the same gene change.

"We can't rerun the tape of life, but we can look back over millions of years of evolutionary divergence and show that there has been tremendous repeatability, even at the molecular level," said Agrawal.


Story Source:

The above story is based on materials provided by Cornell University. The original article was written by Krishna Ramanujan. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Dobler, S. Dalla, V. Wagschal, A. A. Agrawal. Community-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1202111109

Cite This Page:

Cornell University. "Same adaptations evolve across different insects." ScienceDaily. ScienceDaily, 24 July 2012. <www.sciencedaily.com/releases/2012/07/120724144534.htm>.
Cornell University. (2012, July 24). Same adaptations evolve across different insects. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2012/07/120724144534.htm
Cornell University. "Same adaptations evolve across different insects." ScienceDaily. www.sciencedaily.com/releases/2012/07/120724144534.htm (accessed September 1, 2014).

Share This




More Plants & Animals News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. Video provided by Newsy
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
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