Are we underestimating the occurrence of sympatric populations?. Issue 20 (17th September 2018)

• Record Type: Journal Article
• Authors: Jorde, Per Erik; Andersson, Anastasia; Ryman, Nils; Laikre, Linda
• Is Part Of: Molecular ecology. Volume 27:Issue 20(2018)
• Page Start: 4011
• Page End: 4025
• Publication Date: 2018-09-17
• Subjects: biodiversity monitoring -- conservation management -- genetic biodiversity -- population genetic structure; Molecular ecology -- Periodicals; Molecular population biology -- Periodicals; 576
• DOI: 10.1111/mec.14846
• Languages: English
• ISSNs: 0962-1083

Abstract

Abstract: Sympatric populations are conspecific populations that coexist spatially. They are of interest in evolutionary biology by representing the potential first steps of sympatric speciation and are important to identify and monitor in conservation management. Reviewing the literature pertaining to sympatric populations, we find that most cases of sympatry appear coupled to phenotypic divergence, implying ease of detection. In comparison, phenotypically cryptic, sympatric populations seem rarely documented. We explore the statistical power for detecting population mixtures from genetic marker data, using commonly applied tests for heterozygote deficiency (i.e., Wahlund effect) and the structure software, through computer simulations. We find that both tests are efficient at detecting population mixture only when genetic differentiation is high, sample size and number of genetic markers are reasonable and the sympatric populations happen to occur in similar proportions in the sample. We present an approximate expression based on these experimental factors for the lower limit of F ST, beyond which power for structure collapses and only the heterozygote‐deficiency tests retain some, although low, power. The findings suggest that cases of cryptic sympatry may have passed unnoticed in population genetic screenings using number of loci typical of the pre‐genomics era. Hence, cryptic sympatric populations may be more common than hitherto thought, and we urge more attention being diverted to their detection and characterization.