Researchers Try To Identify Gene That Causes Hybrid Incompatibility In Animals
Liger, zonkey, zebroid, hinny, and hogzilla. These are names of a few hybrid animals that are offspring resulting from the mating of two genetically distinct individuals. Hybrids can be found in plants, animals, insects, and fish. But hybrids between two closely related species are often inviable, or if they live, they are sterile. The reason for this is hybrid incompatibility, defined as the failure of two closely related species to produce offspring capable of surviving and reproducing.
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The genetics for hybrid incompatibility has long eluded scientists from Charles Darwin, Thomas Hunt, Morgan and Hermann Joseph Muller to today's geneticists and evolutionary biologists. Darwin, called the "Father of evolution," referred to speciation as the "mystery of mysteries". Speciation is the evolutionary process by which new biological species arise and the role of hybrid incompatibility in speciation is not yet clearly understood by evolutionary biologists.
But now a group of seven scientists from four institutions have tried to identify the genes that cause hybrid incompatibility by using the classic example of hybridization between two different species of fruit flies called Drosophila melanogaster and D. simulans, according to a press release Tuesday. The cross between D. melanogaster and D. simulans generally results in unisexual sterile hybrids. The hybrid males die at the late larval stage, and the sibling females also die at later stages at high temperatures. In previous studies made by Dan Barbash, Ph.D., and colleagues at Cornell University, two genes were found to be responsible for this hybrid incompatibility. They are Hybrid male rescue (Hmr) and Lethal hybrid rescue (Lhr). But studies have shown that only these two genes are not sufficient to cause hybrid inviability in the offspring.
At the GSA (Genetics Society of America) Drosophila Research Conference, Nitin Phadnis, Ph.D., of the University of Utah and his collaborators from the University of Wisconsin, University of Washington, and Fred Hutchinson Cancer Research Center, have identified another gene that may be responsible for the incompatibility. By using new genomics-based approach, the researchers are trying to identify the missing hybrid incompatibility gene in the D. simulans genome. The new approach will also be used to determine the functions of Hmr, Lhr, and the missing gene and how they disrupt the biological pathways in the hybrid offspring.
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