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#59: Gynandromorphs

Litinsects #59: Gynandromorphs

Ok people, pretty sure I’m gonna blow your minds with this one. No, these pictures are not some freakish cut-and-paste Frankenstein experiments. These animals are absolutely real and extremely rare GYNANDROMORPHS.


Common blue gynandromorph (left male, right female)
© Burkhard Hinnersmann

This word comes from the Greek “gyne” for female, “andro” for male, and “morph” for form... meaning that these individuals contain BOTH MALE AND FEMALE tissues!

Firstly, this is not the same thing as a hermaphrodite, which is an organism that contains both types of gonads or can create both sperm and eggs. Gynandromorphs literally have some body parts that are genetically female and others that are genetically male. So I’m sure you’re asking... how?!


Malaysian stick insect (left male, right female)
https://commons.wikimedia.org/wiki/File:Heteropteryx_dilatata_0034b_L.D.jpg

Many different genetic systems exist in the animal kingdom. In humans XX codes for female and XY for male* but other animal groups use different chromosome combinations or different genetic systems entirely to determine sex (even within insects there is variation). In general gynandromorphy usually arises when a CELLULAR ERROR occurs very early in development, while there are only a few cells. If the sex chromosomes separate incorrectly during cell division of one of these early cells, one resulting cell may end up with a number or combination of chromosomes genetically coding for male while the other ends up coding for female. As each of the two cells continues to divide, they produce genetically distinct cell lineages, resulting in a CHIMERA, an organism composed of cells with non-identical genetic material.

-This phenomenon is most well-known in insects and other arthropods such as crustaceans and spiders but has also, perhaps shockingly, been found in birds and reptiles (I encourage you to google)! But it does not occur in mammals

-The most obvious examples have been discovered in species with SEXUAL DIMORPHISM, meaning that within one species the sexes differ in physical characteristics (most commonly size and/or coloration). In butterflies, for example, in which there is a high prevalence of sexual dimorphism, this can lead to some pretty amazing-looking specimens

-Most commonly we see BILATERAL gynandromorphy, meaning that the split is down the middle. But it may also be AXIAL (front/back) or MOSAIC

-Interestingly, some instances of increased abundance of gynandromorphs have been recorded after both the Chernobyl and Fukushima nuclear catastrophes. But whether and how radiation may affect the development of gynandromorphs is just one in a long list of questions that scientists still have about these awesome creatures

*Note that I am referring to chromosomal sex, which is NOT the same as gender!

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