Great Migration: Life for Migrants in the City. By the end of 1919, some 1 million blacks had left the South, usually traveling by train, boat or bus; a smaller number had automobiles or even horse-drawn carts.
Genetic variation is increased by meiosis During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA.
The principle of independent assortment states that genes for different traits can segregate independently during the fo â¦ rmation of gametes. Independent assortment helps account for the many genetic variations observed in plants, animals, and other organisms. 1 person found this useful.