The "how" is through "chromosomal mutations". These types of mutations occur at the chromosomal level (rather than small, single mutation that happen at the level of the nucleotide). For example, a chromosome can literally break in half at some stage during gametogenesis (the formation of eggs an sperm), turning one chromosome into two.
A common example in plants is through whole genome duplication. A plant starts with two copies of each chromosome, it undergoes some kind of mutation which duplicates all the chromosomes - now the plant has four copies of each chromosome. This is actually how plants (like strawberries) have evolved to become bigger and bigger, they have eight copies of each chromosome.
If some chromosomal duplication occurs, the organism now has redundancy in that it has more copies of each gene than it needs. Over time, the extra genes go through specialisation and evolve to become new genes with different properties (this is how gene families evolve).
fruticosa t1_j4zmaji wrote
Reply to Given that reproduction is difficult or impossible when both animals have different numbers of chromosomes, how did so many species evolve to have so many different numbers of them? by MercurioLeCher
The "how" is through "chromosomal mutations". These types of mutations occur at the chromosomal level (rather than small, single mutation that happen at the level of the nucleotide). For example, a chromosome can literally break in half at some stage during gametogenesis (the formation of eggs an sperm), turning one chromosome into two.
A common example in plants is through whole genome duplication. A plant starts with two copies of each chromosome, it undergoes some kind of mutation which duplicates all the chromosomes - now the plant has four copies of each chromosome. This is actually how plants (like strawberries) have evolved to become bigger and bigger, they have eight copies of each chromosome.
If some chromosomal duplication occurs, the organism now has redundancy in that it has more copies of each gene than it needs. Over time, the extra genes go through specialisation and evolve to become new genes with different properties (this is how gene families evolve).