Navigation Links
Electric fish in Africa could be example of evolution in action

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.

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 w e 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.


'"/>

Source:Cornell University News Service


Related biology news :

1. Researchers Discover That Microbes Can Produce Miniature Electrical Wires
2. What can change in the brain? Electrical synapses, research shows
3. Electric jolt triggers release of biomolecules, nanoparticles
4. New push for public health, AIDS spending at African Union summit
5. A comprehensive response to HIV could prevent 10 million AIDS deaths in Africa by 2020
6. Scientists discuss improved biopesticides for locust control in West Africa
7. Reducing malarial transmission in Africa
8. Scientists journey to southern Africa to unravel the secret world of elephant communication
9. Africa to take it on chin again with climate change
10. Study reveals dramatic difference between breast cancers in US and Africa
11. South African Tribunal Asks For Damages Estimates in GSK AIDS Drug Case
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:4/19/2016)... , UAE, April 20, 2016 ... be implemented as a compact web-based "all-in-one" system solution ... the biometric fingerprint reader or the door interface with ... of modern access control systems. The minimal dimensions of ... ID readers into the building installations offer considerable freedom ...
(Date:4/14/2016)... 14, 2016 BioCatch ™, ... today announced the appointment of Eyal Goldwerger ... Goldwerger,s leadership appointment comes at a time ... the deployment of its platform at several of the ... which discerns unique cognitive and physiological factors, is a ...
(Date:3/31/2016)... March 31, 2016  Genomics firm Nabsys has completed ... Barrett Bready , M.D., who returned to the ... original technical leadership team, including Chief Technology Officer, ... Development, Steve Nurnberg and Vice President of Software and ... company. Dr. Bready served as CEO of ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... , June 23, 2016   Boston Biomedical ... novel compounds designed to target cancer stemness pathways, ... been granted Orphan Drug Designation from the U.S. ... of gastric cancer, including gastroesophageal junction (GEJ) cancer. ... designed to inhibit cancer stemness pathways by targeting ...
(Date:6/23/2016)... Prostate Cancer Foundation (PCF) is pleased to announce 24 new Young ... cancer. Members of the Class of 2016 were selected from a pool of ... More About the Class of 2016 PCF Young Investigators ... ... ...
(Date:6/23/2016)... , ... June 23, 2016 , ... In a new ... in Denmark detail how a patient who developed lymphedema after being treated for breast ... results could change the paradigm for dealing with this debilitating, frequent side effect of ...
(Date:6/23/2016)... ... 23, 2016 , ... ClinCapture, the only free validated electronic ... showcase its product’s latest features from June 26 to June 30, 2016 for ... Disrupting Clinical Trials in The Cloud during the conference. DIA (Drug Information ...
Breaking Biology Technology: