Featured Research

from universities, journals, and other organizations

Electric Fish In Africa Could Be Example Of Evolution In Action

Date:
June 2, 2006
Source:
Cornell University
Summary:
Some electric fish in Africa have different communication patterns and won't mate with each other, although their DNA is the same, find Cornell scientists. They think the fish are living examples of a species of fish diverging into separate species.

Although these fish look alike and have the same DNA genetic makeup, they have very different electrical signals and will only mate with fish that produce the same signals. Cornell researchers believe that these different electrical signals are the fishes' first step in diverging into separate species.
Credit: Image Carl Hopkins

Avoiding quicksand along the banks of the Ivindo River in Gabon, Cornell neurobiologists armed with oscilloscopes search for shapes and patterns of electricity created by fish in the water.

Related Articles


They know from their previous research that the various groups of local electric fish have different DNA, different communication patterns and won't mate with each other. However, they now have found a case where two types of electric signals come from fish that have the same DNA.

The researchers' conclusion: The fish appear to be on the verge of forming two separate species.

"We think we are seeing evolution in action," said Matt Arnegard, a neurobiology postdoctoral researcher in the laboratory of Carl Hopkins, Cornell professor of neurobiology and behavior, who has been recording electric fish in Gabon since the 1970s.

The research, published in the June issue of the Journal of Experimental Biology, describes how some of these fish violate an otherwise regular pattern of mating behavior, and so could be living examples of a species of fish diverging into separate species.

The electric fish -- known as mormyrids -- emit weak electric fields from a batterylike organ in their tails to sense their surroundings and communicate with other fish. Each species of mormyrid gives off a single characteristic electric impulse resulting in the flash of signals, indicating, for example, aggression, courtship and fear. While the fish may be able to understand other species' impulses, said Arnegard, "They seem to only choose to mate with other fish having the same signature waveform as their own."

Except for some, Arnegard has discovered.

When he joined Hopkins' lab, the team was about to publish descriptions of two separate species. But when Arnegard decided to take a genetic look at these particular fish, he couldn't find any differences in their DNA sequences.

"These fish have different signals and different appearances, so we were surprised to find no detectable variation in the genetic markers we studied," Arnegard said.

Because all of the 20 or so species of mormyrid have distinct electric signals, Arnegard believes the different impulses of the fish he studies might be their first step in diverging into different species.

"This might be a snapshot of evolution," Arnegard said.

Understanding how animals become different species, a process known as speciation, is a major concern in understanding evolution. Arnegard's fish may allow researchers to test if a specific type of speciation is possible.

One common type of speciation is geographically dependent. Animals diverge into separate species because they become physically isolated from each other. Eventually, genes within each group mutate so that the groups can no longer be considered to be of the same species.

Another type of speciation, which many scientists have found harder to imagine, involves animals that live in the same geographic location but, for some reason, begin to mate selectively and form distinct groups and, ultimately, separate species. This so-called sympatric speciation is more controversial because there have been few accepted examples of it to date.

"Many scientists claim it's not feasible," Arnegard said. "But it could be a detection problem because speciation occurs over so many generations." These Gabon fishes' impulses, however, can change very quickly in comparison. So Arnegard suspects that the different shapes of the electric impulses from these mormyrids might be a first step in sympatric speciation.

One the other hand, the fish could be a single species. "This could be just a polymorphism, like eye color in humans, that violates the fishes' general evolutionary pattern but doesn't give rise to separate species," said Arnegard, who will return to Gabon in June to conduct further tests, funded by the National Geographic Society.


Story Source:

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


Cite This Page:

Cornell University. "Electric Fish In Africa Could Be Example Of Evolution In Action." ScienceDaily. ScienceDaily, 2 June 2006. <www.sciencedaily.com/releases/2006/06/060601213407.htm>.
Cornell University. (2006, June 2). Electric Fish In Africa Could Be Example Of Evolution In Action. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2006/06/060601213407.htm
Cornell University. "Electric Fish In Africa Could Be Example Of Evolution In Action." ScienceDaily. www.sciencedaily.com/releases/2006/06/060601213407.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Birds Around the World Take Flight

Birds Around the World Take Flight

Reuters - Light News Video Online (Nov. 22, 2014) An imperial eagle equipped with a camera spreads its wings over London. It's just one of the many birds making headlines in this week's "animal roundup". Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. 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:

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