Final answer:
Disruptive selection leads to greater genetic variance in a population by favoring individuals with extreme phenotypes at both ends of the spectrum, rather than those with an average phenotype or one particular extreme.
Step-by-step explanation:
The type of selection that results in greater genetic variance in a population is disruptive selection. In contrast to stabilizing selection, which reduces genetic variance by favoring an average phenotype, and directional selection, which favors one extreme phenotype and shifts the population towards it, disruptive selection targets intermediate phenotypes for negative selection. This mode of selection actually favors the extreme phenotypes at both ends of the spectrum. An example of this would be in a population of birds where both very large and very small beak sizes are beneficial, but medium-sized beaks are not. This results in two distinct groups within the same population that have different beak sizes, increasing the overall genetic diversity of the population.