PERSPECTIVE: HIGHLY VARIABLE LOCI AND THEIR INTERPRETATION IN EVOLUTION AND CONSERVATION

TLDR

Highly variable loci, such as microsatellites, are transforming evolutionary and conservation studies, yet their high heterozygosity, sensitivity to bottlenecks, and inflated statistical power can make differentiation measures small, distances misleading, and significant differences biologically uninformative. The study aims to integrate these concerns into the use and interpretation of highly variable loci in evolutionary and conservation research. The authors recommend using variation‑independent metrics, correcting genetic distances for low variation, and applying bottleneck detection tests, noting that high statistical power can obscure biologically meaningful differences.

Abstract

Although highly variable loci, such as microsatellite loci, are revolutionizing both evolutionary and conservation biology, data from these loci need to be carefully evaluated. First, because these loci often have very high within-population heterozygosity, the magnitude of differentiation measures may be quite small. For example, maximum GST values for populations with no common alleles at highly variable loci may be small and are at maximum less than the average within-population homozygosity. As a result, measures that are variation independent are recommended for highly variable loci. Second, bottlenecks or a reduction in population size can generate large genetic distances in a short time for these loci. In this case, the genetic distance may be corrected for low variation in a population and tests to detect bottlenecks are advised. Third, statistically significant differences may not reflect biologically meaningful differences both because the patterns of adaptive loci may not be correlated with highly variable loci and statistical power with these markers is so high. As an example of this latter effect, the statistical power to detect a one-generation bottleneck of different sizes for different numbers of highly variable loci is discussed. All of these concerns need to be incorporated in the utilization and interpretation of patterns of highly variable loci for both evolutionary and conservation biology.