Suppose that a small island population of 130 individuals is visited by 20 sailors who decide to stay and raise families? Suppose also that 45% of the original population had hitchhiker’s thumb and that all of the sailors had hitchhiker’s thumb and that all of the sailors had hitchhiker’s thumb.

a) What are the genotype (TT, Tt, tt) and allele frequencies (T,t) of the next generation?

b) This is an example of what kind of evolutionary force?