A remnant population of giant tortoises on one of the Seychelles islands consists of 80 individuals.
a. If I pick a neutral allele (haplotype) at the same locus from two different tortoises, what is the probability that they shared a common ancestor exactly 4 generations ago (note: tortoises are diploid)?
b. How many generations, on average, would one have to go back to find a common ancestor for all of the tortoises in the population?