Verfügbare Informationen zu "Study: Adaptation To Parasites Drive African Fishes Along Di"
Qualität des Beitrags: Beteiligte Poster: infoshark Forum: SHARK-FORUM Forenbeschreibung: Treffpunkt für Haifans! aus dem Unterforum: Forschung allgemein Antworten: 1 Forum gestartet am: Mittwoch 01.11.2006 Sprache: deutsch Link zum Originaltopic: Study: Adaptation To Parasites Drive African Fishes Along Di Letzte Antwort: vor 16 Jahren, 8 Monaten, 9 Tagen, 6 Stunden, 50 Minuten
Alle Beiträge und Antworten zu "Study: Adaptation To Parasites Drive African Fishes Along Di"
Re: Study: Adaptation To Parasites Drive African Fishes Along Di
infoshark - 17.08.2007, 09:50Study: Adaptation To Parasites Drive African Fishes Along Di
Study: Adaptation To Parasites Drive African Fishes Along Different Evolutionary Paths
Laval, Canada (Aug 16, 2007 18:51 EST) An international team of scientists from Canada (Universitй Laval), the U.K. (University of Hull, Cardiff University) and Spain (Doтana Biological Station), have discovered that a pair of closely related species of East African cichlid fishes – a group of fish whose diversity comprising hundreds of species has puzzled evolutionary biologists for decades – evolved divergent immune gene adaptations which might explain why they do not interbreed, despite living side by side.
The two species ( Pseudotropheus emmiltos and Pseudotropheus fainzilberi ) are found in the north western part of Lake Malawi. Until now, the only known difference between them was the color of their dorsal fin. Many researchers believe that African cichlids recognize conspecifics from these kinds of colour differences, which are thought to result from sexual selection. However, recent mate choice experiments have shown that female P. emmiltos recognize males of their own species from P. fainzilberi males based on olfactory communication rather than color.
Some of the genes known to influence mating behavior through olfaction in other vertebrate species are genes of the major histocompatibility complex (MHC). These genes code for receptor that bound molecules produced by infectious agents and present them to specialized cells of the immune system which then launch an immune attack on the microbes. They are the most diverse genes found in vertebrate genomes and individuals of some species, including humans, are able to "smell" other individuals’ variability at these genes and adjust their mate choice in order to optimize the effectiveness of their offspring's immune system. Analysis of MHC genes between P. emmiltos and P. fainzilberi revealed that the two species were genetically more different at these sites involved in contacting and presenting molecules to immune cells than at other sites of the gene's DNA sequence that do not play functional roles.
These results show that natural selection has driven the evolution of these genes in different direction between the two species. Furthermore, the researchers showed that infecting parasites found on the two species were significantly different, as predicted based on the known immune function of MHC genes. "The mechanisms having produced the hundreds of species of East African cichlid fishes in a relatively short period of time are unclear", says Jonatan Blais, the senior author of the paper." This is one of the first genetic adaptive differences between closely related East African cichlid species identified. As such, it improves our understanding of the recent evolution of this incredibly diverse group of fish by pointing to a trait that not only diverged for adaptive reasons but may also be involved in mating behavior."
"The precise role that this divergence played in the evolution of reproductive isolation has yet to be studied", comments Louis Bernatchez, co-author of the study." But it offers an exciting new perspective in the study of African cichlids speciation ".-Public Library of Science
Mit folgendem Code, können Sie den Beitrag ganz bequem auf ihrer Homepage verlinken
Weitere Beiträge aus dem Forum SHARK-FORUM
Photographer Jim Watt dies - gepostet von infoshark am Dienstag 24.07.2007
Die EU entdeckt den Umweltschutz im Meer - gepostet von infoshark am Montag 18.12.2006
Helfer retten gestrandeten Bryde-Wal - gepostet von infoshark am Dienstag 28.11.2006
Rare Giant Manta Born at Japan Aquarium - gepostet von infoshark am Montag 18.06.2007
Perverse beschießen Wal mit Maschinengewehr - gepostet von infoshark am Montag 10.09.2007
07.06.07 Surfer hurt in shark attack - gepostet von infoshark am Mittwoch 13.06.2007
Mehr Ruhe für die Wale: Forschung und Umweltschutz ziehen an - gepostet von infoshark am Donnerstag 05.04.2007
Ähnliche Beiträge wie "Study: Adaptation To Parasites Drive African Fishes Along Di"
DVD - African Crossbow Safari - Anonymous (Montag 31.10.2005)
African Cup Of Nations 2008 (20 Jan - 10 Feb) - Ghana - Pifas (Donnerstag 10.01.2008)
African Nations Cup - ChurchillWK (Dienstag 07.02.2006)
Parasites suck toxins from sharks - infoshark (Montag 25.06.2007)
African Snake = ein zeichen für SKY - her0 (Donnerstag 19.10.2006)
Kanna -The Ancient African Spirit - derbu (Donnerstag 20.07.2006)
tropical-african-reggae-festivals - Jack Daniel`s (Montag 28.05.2007)