Australia, Madagascar cave fish disvoveries

This composite image shows Typhleotris pauliani (top), a previously known species of Malagasy cave fish, and the newly discovered pigmented species (bottom). Credit: AMNH/J. Sparks

From the American Museum of Natural History in the USA:

Eyeless Australian fish have closest relatives in Madagascar

Researchers are first to show ancient trans-oceanic relationship for vertebrate cave animals

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 small—less than 100 millimeters long—and 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 vicariance—a 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 Gondwana—some 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.'”

… This particular expedition turned into more of an adventure than the group was planning—in 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.”

Deforestation is killing Madagascar’s coral reefs: here.

9 thoughts on “Australia, Madagascar cave fish disvoveries

  1. Madagascar – New Lease of Life for Endangered Species

    28 August 2012

    press release

    With technical support from Conservation International and the World Bank’s BioCarbon Fund, a project is being designed to protect 370,032 hectares of rainforest in Madagascar.

    In the humid rainforest of Madagascar, 14 threatened species of lemurs, found only on the island will soon be able to breathe a little easier. A corridor of forest that stretches along the eastern coast of the island called the Ankeniheny-Zahamena Corridor (CAZ) covers approximately 425,000 hectares. CAZ is a region of rich biological diversity and home to hundreds of local Malagasy communities. The diverse forests provide essential ecosystem services upon which local people rely for their daily subsistence, but they are under pressure from slash-and-burn agriculture, illegal logging and other unsustainable practices.

    By protecting these forests and by focusing on alternative livelihoods, it has been possible to see the link between healthy ecosystems and human well-being. With the fall in deforestation, there has been a significant reduction in carbon emissions. A project is now being developed that will bring monetary benefits to the community for protecting these forests.

    “I switched part of my farming to native species as part of the biodiversity restoration project in the Mantadia-Vohidrazana corridor,”, said Justin Lemiaraka, farmer in the Andasibe community. “In return, with the support of the World Bank and National Association of Environmental Action ANAE, we set up a fish farm with 300 square meter ponds stocked. After my first harvest, I bought a radio which our family had dreamed of for years.”

    Hotbed for Biodiversity

    The CAZ has long been regarded as one of Madagascar’s most precious resources in terms of biodiversity. Over 2,043 species of plants have been identified in its forests, 85% of which are endemic. Also, 30 other species of mammals inhabit the corridor, in addition to 129 species of amphibians and 89 bird species. But the animals that are perhaps best identified with Madagascar are the lemurs, of which there are 101 species on the island. Fourteen lemur species in CAZ are threatened with extinction as their natural habitat slowly disappears due to deforestation from traditional slash and burn agriculture. The communities living in the forests face hardships due to dwindling natural resources on which they depend for their subsistence.

    Carbon Credits for Protecting Forests

    A project is being designed to protect 370,032 hectares of rainforest by linking the Zahamena national park, the Manongarivo special reserve and the Mantadia national park in eastern Madagascar. This voluntary effort, spear-headed by the Ministry of Environment and Forestry (French), Conservation International, and the World Bank’s BioCarbon Fund, aims to reduce emissions from deforestation and forest degradation (REDD) and will provide Verified Emissions Reductions (or carbon credits) that can be sold to finance the future activities of the project and help the local population adapt to the effects of climate change while improving their livelihoods.

    Capturing Lessons Learned and Sharing Experiences

    Some of the carbon credits generated by the project and sold to the World Bank’s BioCarbon Fund will generate revenue to fund conservation activities, including supporting livelihood alternatives for the local communities. The BioCarbon Fund’s support of the project is also expected to shape the understanding of how a REDD project can be implemented and replicated elsewhere. The emission reductions generated by the project have been calculated using a new methodology developed by the BioCarbon Fund and approved internationally by the Verified Carbon Standard. The independent auditor Rainforest Alliance is now conducting a validation of the project documents and will also do what is called a verification of the of the project. Once this is done, the carbon credits can be officially issued and sold to other buyers.

    “CAZ tests an innovative source of financing for the management of protected areas, which also supports local communities in finding alternatives to activities that result in deforestation, such as slash and burn. This project demonstrates how carbon finance can support poverty reduction and biodiversity conservation simultaneously,” said Ellysar Baroudy, head of the World Bank’s BioCarbon Fund.

    By reducing deforestation, a positive cycle is created – the project will allow the ecosystem to recover, and lemur and bird populations will improve. The restored ecosystem also provides additional natural services. On a global level, the sequestration of carbon dioxide helps combat climate change. But more important for the local population is the access to freshwater. The project prevents soil erosion which protects the headwaters of eight large rivers that directly supply water to approximately 325,000 local residents. Water provision and erosion control are also important for the agricultural plains to both the east and west of the corridor, and to the two hydroelectric plants that supply electricity to Madagascar’s two largest cities.

    Innovative Governance Model

    The CAZ Project is also innovative in its introduction of a new governance model based on a hundred local community associations responsible for managing small areas of the forest. Through the project, they gain legal rights to the forest resources. The project also ensures that the benefits from conservation reach those most affected by it.

    “This project provides an important demonstration of how people living around natural tropical forests can be involved in the management of projects designed to reduce greenhouse gas emissions. The challenges of such projects are enormous considering the numbers of people involved, the remote location and the extreme poverty that these people suffer from,” said Léon Rajaobelina, Regional Vice President of Conservation International’s Madagascar program.

    This project – combining the protection of animals and people, while giving local communities sustainable employment opportunities – is an innovative model of how carbon finance can be the catalyst for development.


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