Pikas are small mammals that live at high elevation in the talus slopes of mountains. Most populations located on mountain tops in Colorado and Montana in North America are isolated from one another because pikas don't occupy the low-elevation habitats that separate the mountain tops and don't venture far from the talus slopes. Thus, there is little gene flow between populations. Furthermore, each population is small in size and was founded by a small number of pikas. A group of population geneticists propose to study the amount of genetic variation in a series of pika populations and to compare the allele frequencies in different populations. On the basis of the biology and distribution of pikas, predict what the population geneticists will find concerning the within- and between-population genetic variation.