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A mule is a sterile hybrid of a male donkey and a female horse.Mules are smaller than horses but stronger than donkeys, making them useful as pack animals.. In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction.
In the off-spring of crosses between Drosophila simulans and its island derivative Drosophila mauritiana, female hybrids are fertile but male hybrids are sterile. Recent studies have shown that a critical gene for gender determination in Drosophila known as the sex-lethal gene is highly misregulated in D. melanogaster and D. simulans hybrids ...
However, when hybrids are produced between both species, the gene flow between the two will continue to be impeded as the hybrid males are sterile. Also, and in contrast with the great vigor shown by the sterile males, the descendants of the backcrosses of the hybrid females with the parent species are weak and notoriously non-viable.
Sterile F1 hybrids have given rise to allopolyploids in other taxa (e.g. Spartina and Senecio), but allopolyploids can also form via fertile intermediate hybrids (e.g. Tragopogon). In general, hybrid species can arise from two major types of hybrid speciation, defined by whether the speciation event is associated with genome duplication ...
The U.S. Food and Drug Administration (FDA) now classifies eggs as a “healthy, nutrient-dense" food, according to a new proposed rule. Registered dietitians react to the change.
The U.S. Food and Drug Administration (FDA) announced a new definition of “healthy” food for the first time in 30 years. The new definition will apply to manufacturers who want to call their ...
Ellen DeGeneres is setting the record straight about the status of her new U.K. home amid severe storms that devastated parts of the U.K.. After reports circulated over the weekend that the former ...
Rare, sterile hybrids form between D. pseudoobscura and D. persimilis, with sympatric D. pseudoobscura females discriminating against D. persimilis males; more so than allopatric populations. [42] Other Drosophila research on reinforcement has been from laboratory experiments and is discussed below.