What is a population? An empirical evaluation of some genetic methods for identifying the number of gene pools and their degree of connectivity

RS Waples*, O Gaggiotti

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

1025 Citations (Scopus)

Abstract

We review commonly used population definitions under both the ecological paradigm (which emphasizes demographic cohesion) and the evolutionary paradigm (which emphasizes reproductive cohesion) and find that none are truly operational. We suggest several quantitative criteria that might be used to determine when groups of individuals are different enough to be considered 'populations'. Units for these criteria are migration rate (m) for the ecological paradigm and migrants per generation (Nm) for the evolutionary paradigm. These criteria are then evaluated by applying analytical methods to simulated genetic data for a finite island model. Under the standard parameter set that includes L = 20 High mutation (microsatellite-like) loci and samples of S = 50 individuals from each of n = 4 subpopulations, power to detect departures from panmixia was very high (similar to 100%; P <0.001) even with high gene flow (Nm = 25). A new method, comparing the number of correct population assignments with the random expectation, performed as well as a multilocus contingency test and warrants further consideration. Use of Low mutation (allozyme-like) markers reduced power more than did halving S or L. Under the standard parameter set, power to detect restricted gene flow below a certain level X (H(0): Nm <X) can also be high, provided that true Nm

Original languageEnglish
Pages (from-to)1419-1439
Number of pages21
JournalMolecular Ecology
Volume15
Issue number6
DOIs
Publication statusPublished - May 2006

Keywords

  • UNSAMPLED POPULATIONS
  • migration
  • gene flow
  • ASSIGNMENT METHODS
  • ecological paradigm
  • ENDANGERED SPECIES ACT
  • genetic differentiation
  • ESTIMATING F-STATISTICS
  • MULTILOCUS GENOTYPE DATA
  • SAMPLED POPULATIONS
  • evolutionary paradigm
  • FALSE DISCOVERY RATE
  • PER-GENERATION RULE
  • MIGRATION RATES
  • EVOLUTIONARILY-SIGNIFICANT-UNITS
  • F-statistics
  • assignment tests demographic independence

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