1. (4 pts) We use Fst to measure the number of migrants per generation (Nm) by assuming a balance between the effects of a differentiating evolutionary force and a cohesive evolutionary force. Name those two forces. (Hint, think of the computer simulations of migration)

This structure is determined by the combined effect of deterministic forces and stochastic forces.

Explanation:

Genetic drift refers to random fluctuations in allele frequencies due to chance events , a stochastic (random) force which scrambles the predictable effects of selection, mutation, and gene flow.

Genetic drift is not a potent evolutionary force in very large randomly mating populations. to illustrate the consequences of genetic drift we will consider what happens when drift alone is altering the frequencies of alleles among many small populations. To prove this, we need to understand Population structure, which describes how individuals (or allele frequencies) in breeding populations vary in time and space.