Chromosome 2

hello hiimearl, welcome to the fray.You can think of the reproductive issue this way:Prior to fusion each chromosome matches up with the matching chromosome from the other parent.A mutation occurs that fuses 2a and 2b into one longer chromosome, but otherwise does not alter the string of genes on either 2a or 2b.When mating the fused chromosome can still match up with the two chromosomes from the other parent. This would produce viable offspring.As mutations occur this becomes less possible so either the fused chromosome genotype dies out or the original dual chromosome genotype dies out or the population splits into two reproductively isolated populations and speciation has occurred.We know that such mutations do occur, as they have been documented in living people (see Ask a Geneticist | The Tech Interactive)Enjoy.