Gender Ratios and Genetics
There are many things about Pokémon that strike us animals as odd. One of the things that do and should is the interesting fact that a female Pokémon can mate with a wide range of male Pokémon and yet produce a child of her own species. This would be impossible for any creatures whose reproduction functioned like our own, as the result would inevitably be a blend of the genes from both species. The explanation, therefore, has to be something fundamentally different, and indeed, we find that it is drastically so.
Rather than having their genes split into a large number of chromosomes, as animals do, Pokémon have five long strands of DNA which are coiled into every cell in their bodies. The main two are the masculine genome and the feminine genome, which despite the names are both found in Pokémon of both sexes. The feminine genome is much larger than the masculine genome because it contains the genes coding for the entire structure of the Pokémon's body. The masculine genome codes for the production of proteins that mostly make minor alterations, often giving the Pokémon a better ability to learn certain kinds of techniques known by the father's species or affecting its physical structure minorly by giving it a slightly tougher skin or larger muscles.
The other three strands are the still shorter sex strands, two of which are paternal sex strands and one of which is the maternal sex strand. The sex strands, unlike the masculine and feminine genomes, are not passed on to the child at all, but rather recreated as duplicates of set parts of the masculine and feminine genomes.
To explain: the formation of a Pokémon sex cell begins, like the formation of our sex cells, with an ordinary cell containing all five DNA strands. Let us first use the egg as an example. First, all three sex strands are broken down into their building blocks, which will be used as material for the duplication of the real genome. Now, since we are considering the formation of the egg, first the feminine genome is duplicated in its entirety. A certain part of the masculine genome and a corresponding part of the feminine genome are also duplicated; these are two new maternal sex strands. The masculine genome is broken down in its entirety, and finally the cell splits in two, each containing one copy of the feminine genome and one of the new maternal sex strands.
The formation of the sperm cell is slightly different: first the existing sex strands are broken down, the masculine genome is duplicated in its entirety, and then other parts (not the same as the ones that form the maternal sex strands) of both the masculine and feminine genome are duplicated twice into four new paternal sex strands before the feminine genome is broken down. The resulting sperm cells each contain the whole masculine genome and, randomly, any two of the four new sex strands.
Thus, when the sperm and egg cells combine, the zygote contains one (maternal) sex strand from the egg and two (paternal) sex strands from the sperm, aside from the masculine and feminine genome from the respective parent. The most prominent function of the sex strands is, appropriately, to determine the offspring's sex. This depends on which, if any, of the three sex strands in the zygote are feminine (i.e. originally came from the feminine genome) and which masculine (originating from the masculine genome), and on species-dependent variables in the maternal genome. Each species has one sex dominant and the other recessive, with different species determining sex either based on all three sex strands, only the maternal sex strand, only the paternal sex strands, or in a few cases not at all, with all individuals being of the same sex.
For instance, in a Bulbasaur, the male sex is dominant, and all three sex strands actively determine the sex; if any of them is masculine, the resulting Bulbasaur will be male. Otherwise, it will grow into a female; the chance of all three sex strands being feminine is 1/8.
In a Pikachu, the male sex is dominant; however, since only the maternal sex strand determines their sex, it has a 50% chance of being female anyway.
In a Jynx, the female sex is dominant, and they are invariably female no matter how many masculine sex strands they have, because the sex strands do not affect their sex determination at all.
In the Marill family, the female sex is dominant; however, while an Azurill's sex is determined by the two paternal sex strands (giving it a 1/4 chance of being male, if both are masculine), a Marill or Azumarill's is determined by the maternal sex strand, causing some Azurill to change sexes when they evolve. This is normal and trainers should not panic when it happens.
Naturally, all genderless Pokémon ignore the sex strands for sex determination purposes.
The sex strands also affect the Pokémon in other, subtler ways. Since the parts of the masculine and feminine genome that are duplicated into sex strands are ones that are largely identical or with uniform variation across all Pokémon species, the sex strands are mostly unaffected by the species of the parents.
Ditto
When a Ditto changes its form, it temporarily reproduces the Pokémon's feminine genome within its cells; however, thanks to the influence of its own feminine genome and the ability to spontaneously create sex strands out of its own masculine or feminine genome, it can be whichever sex it likes, even if the other Pokémon's species is technically always one sex. While Ditto reproduce asexually, they are also capable of mating while transformed. If Ditto produces egg cells, they contain the feminine genome of the Pokémon it transformed into and a sex strand from either the masculine or feminine genome of Ditto itself. If a Ditto produces sperm cells, they are created as they would be in a normal Pokémon, using Ditto's true masculine and feminine genomes and creating ordinary sex strands out of them.
Page last modified July 26 2008 at 02:09 GMT
