Navigation Links
Eyeless Australian fish have closest relatives in Madagascar
Date:8/29/2012

A team of researchers from Louisiana State University and the American Museum of Natural History has discovered that two groups of blind cave fishes on opposite sides of the Indian Ocean are each other's closest relatives. Through comprehensive DNA analysis, the researchers determined that these eyeless fishes, one group from Madagascar and the other from similar subterranean habitats in Australia, descended from a common ancestor before being separated by continental drift nearly 100 million years ago. Their study, which appears in the journal PLOS ONE this week, also identifies new species that add to existing biological evidence for the existence of Gondwana, a prehistoric supercontinent that was part of Pangaea and contained all of today's southern continents.

"This is the first time that a taxonomically robust study has shown that blind cave vertebrates on either side of an ocean are each other's closest relatives," said Prosanta Chakrabarty, an assistant professor and curator of fishes at Louisiana State University's Museum of Natural Science. "This is a great example of biology informing geology. Often, that's how things work. These animals have no eyes and live in isolated freshwater caves, so it is highly unlikely they could have crossed oceans to inhabit new environments."

The cave fishes, of the genus Typhleotris in Madagascar and Milyeringa in Australia, are smallless than 100 millimeters longand usually lack pigment, a substance that gives an organism its color and also provides protection from the sun's ultraviolet radiation. These characteristics, coupled with a lack of eyes and enhanced sensory capabilities, allow cave fishes to survive in complete darkness. For this reason, the fishes have very restricted distributions within isolated limestone caves. It's also why the newfound genetic relationship between the trans-oceanic groups is an exciting geological find.

"The sister-group relationship between cavefishes from Madagascar and Australia is a remarkable example of Gondwanan vicariancea geographical split dating back to the Late Cretaceous some 100 million years ago," said John Sparks, a curator in the Division of Vertebrate Zoology at the American Museum of Natural History. "The interesting thing about Madagascar's extant freshwater fish groups, with the exception of a single species, is that all exhibit relationship patterns that are in time with the Mesozoic breakup of Gondwanasome are related to groups in India/Sri Lanka, and others to groups in Australia. Only a single freshwater species has its closest relative in nearby Africa."

One of the new species discovered by the researchers, which will be named in a future publication, is a novelty among cave fishes because it is fully and darkly pigmented. The analysis the researchers conducted for this fish's tree of life shows that it evolved from a pigment-free ancestor, indicating that some subterranean forms can "reverse" themselves for this character.

"It is generally thought that cave organisms are unable to evolve to live in other environments," Sparks said. "Our results, and the fact that we have recently discovered new cave fish species in both Madagascar and Australia belonging to these genera, are intriguing from another perspective: they show that caves are not so-called 'evolutionary dead ends.'"

Funding for the research expedition was provided by the Constantine S. Niarchos Expedition Fund, established by the Stavros Niarchos Foundation to support the research of museum curators around the globe. This particular expedition turned into more of an adventure than the group was planningin fact, one of the new species has been given a moniker that means "big sickness" in Malagasy because of the dangers the team incurred while searching for specimens in this dry, inhospitable region of Madagascar.

"Only two specimens of the new pigmented form were recovered from the first cave we searched in Madagascar, despite the fact that we spent hours in this sinkhole," said Chakrabarty. "Even the locals hadn't been inside of it before."

Because remote locales with caving opportunities exist all over the world, the researchers are eager to pursue other opportunities for discovery.

"Conducting this research really developed my love for caving," said Chakrabarty. "You don't always find something exciting. But, when you consider how isolated many of these caves are, especially in places like Madagascar, and how unaffected they have been by the passage of time, you know that the fish in there are going to tell a really good story."


'/>"/>
Contact: Kendra Snyder
ksnyder@amnh.org
212-496-3419
American Museum of Natural History
Source:Eurekalert  

Related biology news :

1. Ancient whale species sheds new light on its modern relatives
2. Researchers look to relatives for clues in quest to develop sources of bioenergy
3. Time is ticking for some crops wild relatives
4. The EU underpays Madagascar for access to fish: UBC research
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Eyeless Australian fish have closest relatives in Madagascar
(Date:6/23/2017)... and ITHACA, N.Y. , June 23, ... University, a leader in dairy research, today announced a ... to help reduce the chances that the global milk ... of this dairy project, Cornell University has become the ... the Food Supply Chain, a food safety initiative that ...
(Date:5/23/2017)... May 23, 2017  Hunova, the first robotic gym for the rehabilitation ... officially launched in Genoa, Italy . The first 30 ... and the USA . The technology was developed and ... by the IIT spin-off Movendo Technology thanks to a 10 million euro ... Release, please click: ...
(Date:5/16/2017)... May 16, 2017   Bridge Patient Portal ... and MD EMR Systems , an electronic ... for GE, have established a partnership to build ... and the GE Centricity™ products, including Centricity Practice ... These new integrations will allow healthcare ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... ... October 11, 2017 , ... Proscia ... be hosting a Webinar titled, “Pathology is going digital. Is your lab ready?” ... pathology adoption best practices and how Proscia improves lab economics and realizes an ...
(Date:10/11/2017)... Austin, TX (PRWEB) , ... October 11, 2017 ... ... in August compared the implantation and pregnancy rates in frozen and fresh ... the contribution of progesterone and maternal age to IVF success. , After comparing ...
(Date:10/10/2017)... ... 10, 2017 , ... For the second time in three ... Mentoring Award. Representatives of the FirstHand program travelled to Washington, D.C. Tuesday, October ... US2020’s mission is to change the trajectory of STEM education in America by ...
(Date:10/10/2017)... CALIFORNIA (PRWEB) , ... October 10, 2017 , ... ... technological innovation and business process optimization firm for the life sciences and healthcare ... BoxWorks conference in San Francisco. , The presentation, “Automating GxP Validation for ...
Breaking Biology Technology: