How does polyploidy allow speciation to occur in a single generation? Polyploid offspring produce gametes earlier in the mating season than than their diploid parents, causing reproductive isolation between the two generations. Polyploid offspring produce smaller gametes that disperse farther than the gametes of diploid parents, causing geographic isolation between the two generations. Physiological differences between polyploid offspring and their diploid parents allow them to thrive in different environments, causing geographic isolation between the two generations. Genomic differences between polyploid offspring and their diploid parents prevent them from successfully interbreeding, causing reproductive isolation between the two generations.