Montana
Well-known member
Sexual dimorphism is an interesting topic to discuss. Let me jump in here!
According to these documents:
http://www.jstor.org/stable/3222493
http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/12556/1/10(1)_p1-27.pdf
Male mantids have 27 chromosomes while females have 28, at least in Mantis religiosa. Not only that, but there appears to be a good size discrepancy in what we may call the "sexual" chromosomes (similar to the X and Y chromosomes of humans and mammals).
The extra chromosomes that females possess, plus the length discrepancy in the sexual chromosomes, may account for the sexual dimorphism - including the crests and necklaces discussed above. We cannot discount the possibility that males and females may have the same genes for these features, but males express some genes while females express others. Chromosomal differences and gene expression likely account for the observed sexual dimorphism.
Another interesting point that I'd like to add is that plants may undergo mutations that double their chromosome number (polyploidy). Sometimes this leads to healthier, more robust plants and expresses new traits. It may also lead to sterility. For example, many of the fruits (often seedless due to sterility from polyploidy) we purchase at markets today have this condition, like bananas and watermelons. So, for better plants and better fruits, more chromososmes are better for plants. This page summarizes these facts quite nicely: http://assoc.garden.org/courseweb/course2/week3/page18.htm
While more chromosomes are better for plants, we can't necessarily say the same for all animals. The YY sex chromosome condition in humans leads to natural abortion (not viable, you need that X chromosome for vital functions), while the X, XXX and XXY conditions produce developmental defects, even sterility, but still develop into living human beings.
SO the point is that it's hard to tell for sure without thorough genetic analysis, but the difference in features likely factors down to sex chromosomes and gene expression, while size may also be influenced by the chromosome count itself.
And one last note... things get really interesting once you start asking what the deal is with the Brunner's mantis, which is self-fertile and births no males. Or when you try to interbreed mantids. There may also be mantids with more or fewer chromosomes than Mantis religiosa. Oh, the science of genetics! So much to be explored and unlocked!
According to these documents:
http://www.jstor.org/stable/3222493
http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/12556/1/10(1)_p1-27.pdf
Male mantids have 27 chromosomes while females have 28, at least in Mantis religiosa. Not only that, but there appears to be a good size discrepancy in what we may call the "sexual" chromosomes (similar to the X and Y chromosomes of humans and mammals).
The extra chromosomes that females possess, plus the length discrepancy in the sexual chromosomes, may account for the sexual dimorphism - including the crests and necklaces discussed above. We cannot discount the possibility that males and females may have the same genes for these features, but males express some genes while females express others. Chromosomal differences and gene expression likely account for the observed sexual dimorphism.
Another interesting point that I'd like to add is that plants may undergo mutations that double their chromosome number (polyploidy). Sometimes this leads to healthier, more robust plants and expresses new traits. It may also lead to sterility. For example, many of the fruits (often seedless due to sterility from polyploidy) we purchase at markets today have this condition, like bananas and watermelons. So, for better plants and better fruits, more chromososmes are better for plants. This page summarizes these facts quite nicely: http://assoc.garden.org/courseweb/course2/week3/page18.htm
While more chromosomes are better for plants, we can't necessarily say the same for all animals. The YY sex chromosome condition in humans leads to natural abortion (not viable, you need that X chromosome for vital functions), while the X, XXX and XXY conditions produce developmental defects, even sterility, but still develop into living human beings.
SO the point is that it's hard to tell for sure without thorough genetic analysis, but the difference in features likely factors down to sex chromosomes and gene expression, while size may also be influenced by the chromosome count itself.
And one last note... things get really interesting once you start asking what the deal is with the Brunner's mantis, which is self-fertile and births no males. Or when you try to interbreed mantids. There may also be mantids with more or fewer chromosomes than Mantis religiosa. Oh, the science of genetics! So much to be explored and unlocked!
