Lake Victoria and Fish

Scientists Discover Fish in Act of Evolution in Africa’s Greatest Lake

cichlids-fish-species-evolving-in-lake-victoria In what could be a first in the world, a fish species in the cichlid family has been observed by scientists in the act of splitting into two distinct species in Lake Victoria, Africa’s largest lake and one of the world’s biggest fresh water bodies.

This may be remarkable because what is causing them to diverge are adaptations to their vision as animals and plants try to cope with increased pollution and the effects of climate change. The change is also happening without geographical isolation, which was thought to be a precursor for evolution.

The Pundamilia nyererei is a haplochromine type cichlid native to areas in the Mwanza Gulf region of Lake Victoria. This region consists of many islands where each island region has its own color variant of the fish.

In a report published in the journal Nature, researchers from Tokyo’s Institute of Technology and the Swiss Federal Institute of Aquatic Science and Technology have observed the cichlid evolve into a new species better adapted in sighting its prey and predator.
But the scientists have also tabled evidence indicating that it is not pollution and over-fishing alone that are responsible for the disappearance of some fish species in Lake Victoria and the evolving of others like the cichlid into new species.
The report summarizes that new species may be born because of vision differences and what fish see at least in one African lake could be the driving force that causes them to evolve into new species.

This may explain the very rapid loss of pundamilia in Lake Victoria over the past 30 years. The study says the eye adaptations have also affected mating patterns.
Researchers looked at two species, conspicuous by their red or blue colours. They determined through lab experiments that certain genetic mutations helped some fish adapt their vision at deeper levels to see the colour red and others in shallower water to recognise shades of blue.

The researchers showed that the eyes have adapted to this difference so that fish that live in deeper water have a pigment in their eyes that is more sensitive to red light, while shallow-water fish were sensitive to blue.

Generally, the evolutionary process of speciation (the formation of new species) occurs when one species is split by a physical distance or barrier, allowing each group to develop different traits. The observations of Lake Victoria’s cichlids provide evidence of an unusual form of evolution known as sympatric speciation, which occurs without the physical separation of a population group.


Comment By Jeniffer .B(New York)

This may not be sympatric speciation but  a possiblitity of deep water dwelling fish coming  to adapt to the surface as result of overfishing the top layer dwelling species. To be able to appreciate this purported evolutionary nyererei species, we need to know all the types of fish, their color, at different water depth habitats as well as their visual color acuties. then we compare,physically,macro and micro -genetics.  One needs to appreciate the enormous diversity of the acquatic /marine animal diversity before they conclude and jump up and down as new discoverers of the new species. I see all kinds of fish in fish tanks everyday, and for L.victoria, one of the world’s youngest lakes, cased in the heart of the poor Africa away from the aggressive and rich scientific researchers of the west,it is hard to accept such discoveries without serious thought. How long did the research last, how many fish species did lake Victoria have say twenty years ago, which types have gone extict and which ones are now new.Which species dwell where , bottom, sides, or surface of the lake? What colors do the different types of fish respond to in their sight. How far do they see, what pigment is giving the fish color, idodine, bromine ,chlorophyl (green, blue or red). Bromine is the commonest marine halide that gives color to aquatic animals, so what has changed here. These are some of the issues we need to know in order to celebrate the new discovery.

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