Exam 9: Evolution at Multiple Loci

A study of susceptibility to major depressive disorder in monozygotic twins separated at birth revealed that the broad-sense heritability of this trait is 0.10, and its total phenotypic variance is 0.25. What is the variance of the genotypic value of this disorder? Show your work.

If we are interested in the A, B, and C loci of a diploid organism, which of the following would be a possible haplotype?

Narrow-sense heritability is defined as the ________ genetic variation divided by the ________ variation.

The figure shown demonstrates the genotypic adaptive landscape for bacteria growing in media without antibiotics. The height of the bars associated with a genotype indicates the fitness of that genotype. The R allele confers resistance to antibiotics, and the C allele compensates for the loss of fitness that the R allele confers in the absence of antibiotics. The rc haplotype lacks both compensation and resistance. Based on this landscape, why are resistance and compensation unlikely to be lost even in the absence of antibiotics?

What processes generate, and what processes remove, linkage disequilibrium?

What is one reason why antibiotic resistance does not always disappear as quickly as one might expect after large-scale antibiotic use is ended?

Why would we expect genotypic adaptive landscapes to have rugged contours?