Research led by New York University biologists shows that the cavefish are an example of convergent evolution, with several populations repeatedly, and independently, losing their sight and pigmentation. Their study appears in BioMed Central’s open access journal, BMC Evolutionary Biology.
The blind cavefish and the surface dwelling Mexican tetra, despite appearances, are the same species and can interbreed. The cavefish are simply a variant of the Mexican tetra, albeit ones adapted to living in complete darkness. A team of researchers from Portugal, the United States, and Mexico studied the DNA from 11 populations of cavefish (from three geographic regions) and 10 populations of their surface-dwelling cousins to help understand the evolutionary origin of the physical differences between them.
While results from the genotyping showed that the surface populations were genetically very similar, the story for the cave populations was very different. The cave forms had a much lower genetic diversity, probably as a result of limited space and food. Not surprisingly, the cave populations with the most influx from the surface had the highest diversity. In fact, there seemed to be a great deal of migration in both directions.
It has been thought that, historically, at least two groups of fish lived in the rivers of Sierra de El Abra, Mexico. One group originally colonized the caves, but became extinct on the surface. A different population then restocked the rivers and also invaded the caves.
Richard Borowsky, from the Cave Biology Group at NYU and one of the paper’s co-authors, explained, “We were fortunate in being able to use A. mexicanus as a kind of ‘natural’ experiment where nature has already provided the crosses and isolation events between populations for us. Our genotyping results have provided evidence that the cave variant had at least five separate evolutionary origins from these two ancestral stocks.”
Martina Bradic, an NYU postdoctoral fellow who led the research, conducted the study as part of her graduate work.
“Despite interbreeding and gene flow from the surface populations, the eyeless ‘cave phenotype’ has been maintained in the caves,” she said. “This indicates that there must be strong selection pressure against eyes in the cave environment. Whatever the advantage of the eyeless condition, it may explain why different populations of A. mexicanus cave fish have independently evolved the same eyeless condition, a striking example of convergent evolution.”
Notes to Editors1. “Gene flow and population structure in the Mexican blind cavefish complex” (Astyanax mexicanus)
BMC Evolutionary Biology (in press)Before the embargo lifts, the article is available at: http://bit.ly/w3P0yl
Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central’s open access policy.
Article citation and URL available on request at firstname.lastname@example.org on the day of publication.
2. BMC Evolutionary Biology is an open access, peer-reviewed journal that considers articles on all aspects of molecular and non-molecular evolution of all organisms, as well as phylogenetics and palaeontology.
3. BioMed Central (http://www.biomedcentral.com/) is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.
James Devitt | Newswise Science News
New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego
Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
16.01.2018 | Materials Sciences
16.01.2018 | Materials Sciences
16.01.2018 | Power and Electrical Engineering