B. Linkage disequilibrium determines whether selection at one locus affects allele and genotype frequencies at another locus Whether a population is in linkage equilibrium or disequilibrium critically affects the evolution of the population. If the population is in linkage equilibrium, then selection at one locus is independent of selection at other loci. If a population is in equilibrium disequilibrium, then selection at one locus also changes the genotype frequencies at one or more other loci. The effect of sexual reproduction with random mating is to reduce the level of linkage disequilibrium in populations. Asexual reproduction has advantages- it tends to be faster, for example.
Harmful mutations are more common than beneficial ones.
Selection acts against deleterious mutations, but new mutations arise and recessive mutations persist for a long time. There can be a selection-mutation equilibrium. Over time, there will be a tendency for the zero-class to get smaller, in part because of new mutations arising and in part because drift may, by chance, wipe out the relatively small number of individuals with zero mutations. Thus the mutational load will tend to increase in asexual populations. In sexual populations, a lineage can purge all or part of the mutational load.