Current Status
Examples of saltational evolution include cases of stabilized hybrids that can reproduce without crossing (such as allotetraploids) and cases of symbiogenesis. Evidence of phenotypic saltation has been found in the centipede and some scientists have suggested there is evidence for independent instances of saltational evolution in Sphinx moths. Some processes of epigenetic inheritance can also produce changes that are saltational. There has been a controversy over if mimicry in butterflies and other insects can be explained by gradual or saltational evolution. According to (Norrstrom et al. 2007) there is evidence for saltation in some cases of mimicry. The endosymbiotic theory is considered to be a type of saltational evolution.
Specific cases of homeosis in flowers can be caused by saltational evolution. In a study of divergent orchid flowers (Bateman and DiMichele, 2002) wrote how simple homeotic morphs in a population can lead to newly established forms that become fixed and ultimately lead to new species. They described the transformation as a saltational evolutionary process, where a mutation of key developmental genes leads to a profound phenotypic change, producing a new evolutionary linage within a species. Polyploidy (most common in plants but not unknown in animals) is considered a type of saltation. Polyploidy meets the basic criteria of saltation in that a significant change (in gene numbers) results in speciation in just one generation. Mammalian liver cells are typically polyploidal, but they are not part of the germ line.
Read more about this topic: Saltation (biology)
Famous quotes containing the words current and/or status:
““I” is a militant social tendency, working to hold and enlarge its place in the general current of tendencies. So far as it can it waxes, as all life does. To think of it as apart from society is a palpable absurdity of which no one could be guilty who really saw it as a fact of life.”
—Charles Horton Cooley (1864–1929)
“Knowing how beleaguered working mothers truly are—knowing because I am one of them—I am still amazed at how one need only say “I work” to be forgiven all expectation, to be assigned almost a handicapped status that no decent human being would burden further with demands. “I work” has become the universally accepted excuse, invoked as an all-purpose explanation for bowing out, not participating, letting others down, or otherwise behaving inexcusably.”
—Melinda M. Marshall (20th century)