“...the inborn genetic ability to change reproductive sex one or more times during the organism’s lifetime.”
Higher forms of life? For instance?
“Higher forms of life? For instance?”
Now you are getting into some very very complex subject matter about which researchers are still only scratching the surface. The examples which come most immediately to mind are fish, frogs, and so forth. However...exceptions are being discovered in the higher lifeforms. Recent research has also found the genes in females and in males which are required to function correctly to PREVENT the occurrence of a spontaneous and natural natural sex change in humans. Yes, you have to read that line a few times with some understandable incredulity. be that as it may:
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Researchers at the University of Minnesota Medical School and College of Biological Sciences have discovered a gene that is required to maintain male sex throughout life.
The research team, led by David Zarkower and Vivian Bardwell of the University of Minnesota’s department of genetics, cell biology, and development, found that removing an important male development gene, called Dmrt1, causes male cells in mouse testes to become female cells. The findings were published today in the online edition of Nature.
[....]
Previous research has shown that removing a gene, called Foxl2, in ovaries caused female cells to become male cells and the ovaries to become more like testes. According to Zarkower, this latest research determines that the gonads of both sexes must actively maintain the original sex determination decision throughout the remainder of life.
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The sex determination systems of various lifeforms are often dramatically different. They vary dramatically even among mammalian species. Example:
Platypus sex ‘master switch’ identified
http://www.advocate.com/news/daily-news/2011/07/21/researchers-discover-sex-change-gene
Changes in the sex determination system for humans is normally a function of the chromosomal sex determinations, so the epigenetic causes tend to be a lesser control of sex determination. Accordingly, natural reversals of sex and sex determination in humans is not something you should expect to see unless those specific control genes like Dmrt1 and Fox12 have been affected.