Related questions with answers

A segment of DNA in an individual may differ at several nucleotide positions from a corresponding DNA segment in another individual. For instance, one individual may have the sequence $\dotsb$ A $\dotsb$ G $\dotsb$ C $\dotsb$ and another individual may have the sequence $\dotsb$ T $\dotsb$ A $\dotsb$ A $\dotsb$ . These two DNA segments differ in three nucleotide positions.Because the nucleotides within each segment are tightly linked, they will tend to be inherited together as a unit, that is, without being scrambled by recombination. We call such heritable units DNA haplotypes. Through sampling and DNA sequencing, researchers can determine which DNA haplotypes are present in a particular population. When this kind of analysis is performed on human populations by sequencing, for example, a segment of mitochondrial DNA, it is found that samples from Africa exhibit more haplotype diversity than samples from other continents. What does this observation tell us about human evolution?

The prune gene (symbol pn) is X-linked in Drosophilavmelanogaster. Mutant alleles of this gene cause the eyes to be brown instead of red. A dominant mutant allele of another gene located on a large autosome causes hemizygous or homozygous pn flies to die; this dominant mutant allele is therefore called Killer of prune (symbol Kpn). How could mutants such as these play a role in the evolution of reproductive isolation between populations?

Distinguish between allopatric and sympatric modes of speciation.