Sunday, March 09, 2008
environment, DNA and sex determination
Sex determination and temperature
Short trip into biology and genetics and epigenetics
To biologists it is known for ages that some species evolve male or female offspring by temperature of the environment. Some reptiles have male offspring when their eggs are exposed to higher temperature, and some have female offspring. The same is environmental influence of temperature occurs in some fish and some other species.
Some species change the sex based on the body size. If the body is relatively small it is female, when the body grows and reaches certain size it becomes male. But let’s return to the influence of temperature.
It is not only reptiles and fish that react to the temperature of the environment. Trees react to it too. If the temperature falls constantly over a period of time - winter is coming - then the trees let their leaves fall.
In human females temperature can be used as indicator for ovulation. There are many more instances of environment variables influencing some phenotypic phenomenon.
Until now biologist are not sure why this sex determination via temperature functions. I, of course, do not know that either, but I would like to suggest a possible solution of the question. Sex chromosomes are only DNA with all the attributes of genetics and especially of epigenetics. So it might be possible that temperature changes some chemicals in DNA, maybe some methyl groups, or even something else and this in turn then, changes the expression of the chromosome and as a result either male or female offspring develops.
I think that the idea that temperature influences DNA is a viable way, though it may happen that the results will be negative, in such a case some other coding influence of temperature must be looked for.
Short trip into biology and genetics and epigenetics
To biologists it is known for ages that some species evolve male or female offspring by temperature of the environment. Some reptiles have male offspring when their eggs are exposed to higher temperature, and some have female offspring. The same is environmental influence of temperature occurs in some fish and some other species.
Some species change the sex based on the body size. If the body is relatively small it is female, when the body grows and reaches certain size it becomes male. But let’s return to the influence of temperature.
It is not only reptiles and fish that react to the temperature of the environment. Trees react to it too. If the temperature falls constantly over a period of time - winter is coming - then the trees let their leaves fall.
In human females temperature can be used as indicator for ovulation. There are many more instances of environment variables influencing some phenotypic phenomenon.
Until now biologist are not sure why this sex determination via temperature functions. I, of course, do not know that either, but I would like to suggest a possible solution of the question. Sex chromosomes are only DNA with all the attributes of genetics and especially of epigenetics. So it might be possible that temperature changes some chemicals in DNA, maybe some methyl groups, or even something else and this in turn then, changes the expression of the chromosome and as a result either male or female offspring develops.
I think that the idea that temperature influences DNA is a viable way, though it may happen that the results will be negative, in such a case some other coding influence of temperature must be looked for.
# posted by Dalibor @ 3:43 AM 
