In what could explain earlier findings that just a small number of genetic changes control the widespread evolution of many species of sticklebacks, researchers report in the March 25, 2005, Science that mutations in a single gene appear to be responsible for the changes in the armor of these widespread fish.

David Kingsley of Stanford Medical School and the Howard Hughes Medical Institute and colleagues found that reductions in the armor of threespine sticklebacks that have migrated from marine water to freshwater is an example of parallel evolution derived from an allele on a single gene, Eda.

"This finding shows that while the morphological change is large, the underlying genetics are simple," Kingsley told The Scientist. Marine water fish carry the genetic change at such a low frequency that individual animals do not carry homozygous alleles for the gene, a condition required for the development of low-plated...

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