Sentences with phrase «cichlid species»

Using nuclear haplotypes with microsatellites to study gene flow between recently separated Cichlid species Hey, J., Y. Won, A. Sivasundar, R. Nielsen, et al. 2004.

Different feeding regimes resulted in differences in head morphologies in both New and Old World cichlid species.

The sequenced species include the Nile tilapia, representing the ancestral lineage, and four East African species: a species that inhabits a river near Lake Tanganyika; a species from Lake Tanganyika that appeared 10 - 20 million years ago; a cichlid species from Lake Malawi that appeared less than 5 million years ago; and a very recent species from Lake Victoria that radiated less than 15,000 to 100,000 years ago.

Descendants of the genetically diverse hybrid population colonized the lake and, within the evolutionarily short period of several thousand years, diverged to form around 500 new (endemic) cichlid species, with a wide variety of ecological specializations.

In a study published in Nature Communications, they demonstrate for the first time that this rapid evolution was facilitated by earlier hybridization between two distantly related cichlid species from the Upper Nile and Congo drainage systems.

The hybridization of two divergent cichlid species enabled genetic variants to be recombined on a scale which would not otherwise be possible in a single population.

But after the Nile perch was introduced — for commercial reasons — in the 1950s, and the lake also experienced substantial eutrophication, about half of the cichlid species became extinct.

But while a number of cichlid species, feeding largely on crustaceans or plants, managed to adapt and recover, of the 100 or so species which, like the Nile perch, live on larger fish, more than 80 became extinct.

Over the past 15,000 years, around 500 cichlid species developed in the geologically young Lake Victoria.

This was the conclusion of research conducted by Eawag and Bern University scientists on cichlid species in Lake Victoria, which suffered mass extinction following the introduction of the fish - eating Nile perch in the 1950s.

The reason for this may be a consequence of the way of life of this cichlid species: The females deposit their eggs in breeding caves and care for them intensively.

This dataset is based on the painstaking analysis of X-ray photographs of the skeletons of 763 individuals belonging to 227 modern cichlid species.

«This combination of characters is particularly interesting, because molecular geneticists have shown that many of the cichlid species in Lake Tanganyika possess «mosaic» genomes — made up of genetic material derived from non-related species.

If our estimates are correct, there could be twice as many cichlid species in these three lakes as there are freshwater fish in the whole of Europe and North America.

Not exact matches

Most species of cichlid live in three lakes in Africa's Great Rift Valley.

Over a remarkably short period, cichlids in the African great lakes have spawned hundreds of new species, with an enormous range of characteristics.

Neolamprologus obscurus is a highly sociable species of cichlid found only in the southern reaches of Lake Tanyanika.

Moreover, the results are consistent with molecular genetic data relating to the ongoing diversification of the family in the Great Lakes region of East Africa, which have indicated that hybridization between members of related species or even genera has played a major role in cichlid speciation.

But the Lake Victoria cichlids far surpass Darwin's finches in the astonishing speed with which they diversified: the more than 500 species that live there and only there today all evolved within the past 15,000 to 10,000 years — an eyeblink in geologic terms — compared with the 14 finch species that evolved over several million years.

Like Charles Darwin's famous finches, which evolved a wide range of beak shapes and sizes to exploit the different foods available in the Galápagos Islands, these cichlids represent a textbook example of what biologists term an adaptive radiation — the phenomenon whereby one lineage spawns numerous species that evolve specializations to an array of ecological roles.

The basin now occupied by Lake Tanganyika came into being at least 5.5 million years ago, and it has been assumed that the species radiation that gave rise to the striking diversity of cichlids in the lake was triggered by its formation.

«This unique resource has made it possible for the first time to place a new fossil species securely within the phylogeny of African cichlids.

Indeed, our analysis shows it to be a member of the most ancient cichlid lineage that contributed to the so - called East African Radiation, a spectacular burst of diversification that has given rise to a huge variety of species,» Reichenbacher explains.

They don't signal their ascent from beta to alpha status by turning bright blue, as do males from one species of African cichlid fish.

Lake Malawi, shared by Malawi, Mozambique, and Tanzania, is home to at least 500 species of cichlids, all of which probably took less than a million years to evolve from a common ancestor.

Fernald studies Astatotilapia burtoni, one of the hundreds of cichlid fish species inhabiting Lake Tanganyika in eastern Africa, because of the unique ways they have evolved over time.

The extraordinary diversity of cichlid fishes challenges entrenched ideas of how quickly new species can arise

Incipient species of African cichlid fish have divergent genomic islands associated with mate choice.

There are over 250 species of cichlid in the lake: their presence seems to have blinded biologists to other examples of evolution in action occurring there.

«In each of the two crater lakes new species of the Midas cichlid evolved with an elongated body — a phenotype that does not exist in ancestral lakes from which the colonisers of crater lakes came from,» explains Meyer.

Richard Francis and his colleagues at the University of Oregon in Eugene and the University of Washington in Seattle studied a species of cichlid fish found in Lake Tanganyika.

They sequenced 10 nuclear genes from 89 modern species of cichlids and 69 other fish to come up with dates when cichlids diverged from their fishy relatives.

More than 1600 species of cichlids swim in fresh water around the world, spanning a rainbow of colors and a myriad of shapes.

«Significant impacts to the lake could result from incidental or accidental spills from 5,100 ships passing through every year; invasive species brought by transoceanic ships, which could threaten the extinction of aquatic plants and fish, such as the cichlids that have been evolving since the lake's formation; and frequent dredging, impacting aquatic life through alterations in turbidity and hypoxia, triggered by resuspension of nutrients and organic matter that exert a relatively high biochemical oxygen demand.»

Sympatric speciation occurs when new species emerge without separation, such as the 13 species of Galapagos finch or Africa's cichlid fish.

«The Nile perch, preying on cichlids, did indeed decimate stocks of these species in Lake Victoria,» says Matt McGee, who studied the ecology and evolution of fish - eating cichlids for his doctoral thesis at the University of California, Davis, and is now carrying out research on invasive fish species with Ole Seehausen at Eawag and Bern University.

What slows cichlids down is the second set of jaws at the back of their throat — the pharyngeal jaws — which originally enabled these species to exploit a wide range of food sources.

The cichlid, Neolamprologus furcifer, raises its brood in rocky nests near the lake shore — a habitat shared with various snail species.

This predator cichlid now only exists in the Lake Victoria Species Survival Program.

Researchers have found that one species of cichlid uses urine to send chemical signals to rivals during aggressive displays.

Depending on the species, cichlids may scrape algae from rocks, feed on plankton, crack open snail shells, forage for insect larvae, or prey on other fish, including their eggs or scales.

The particular genetic diversity and adaptive capacity of Lake Victoria's cichlids is demonstrated by the fact that more than 40 other fish species which colonized the lake at the same time have barely changed since then.

We tested species of Malawi cichlids found in rocky reefs, open sand habitats, or the sand - rock interface for a variety of environment - usage phenotypes in a controlled laboratory setting.

Like Darwin's finches, the cichlids are a dramatic example of adaptive radiation, the process by which multiple species «radiate» from an ancestral species through adaptation.

The East African cichlid fishes of Lake Malawi are ideal for investigating behavioral adaptation to environment, as within genera, fine - scale niche partitioning has resulted in sympatric sister species that live in definable microhabitats with distinct selection pressures.

This hypothesis was experimentally tested by determining the effect of different diets on the head and jaw morphology of split broods of several species of haplochromine cichlids from Lake Malaŵi, Africa, and two substrate - spawning cichlids, one from the Old World, Tilapia mariae (Boulenger), and one from the New World, Herichthys cyanoguttatum (Baird and Girard).

Ole Seehausen, senior author and Head of Fish Ecology and Evolution at Eawag Aquatic Research, said: «African cichlid fish stand out amongst fish by their incredible richness of species that evolved without geographical isolation and that now coexist within individual lakes.

In an effort to understand the molecular basis of adaptation in vertebrates, researchers sequenced the genomes and transcriptomes of five species of the African cichlid fish.

Comparative genomic analysis from 82 wild and wild - derived species grouped by microhabitat - use identified variation corresponding with one of these QTL, further supporting broad association with habitat use across the Malawi cichlid radiation.

Using the cichlid fish species as a model system gives us valuable insight into human biology and disease.