Table 1 Brief description of population genetic methods used in the focal studies
From: The population genetics of crypsis in vertebrates: recent insights from mice, hares, and lizards
Demographic inference | ||||
|---|---|---|---|---|
Method | Data | Definition | Selection | As used in |
δaδi (Gutenkunst et al. 2009) | Site frequency spectrum (SFS) from one population or the joint frequency spectrum from multiple populations; calculated from neutral polymorphisms | Likelihood of demographic model is calculated using a diffusion approximation | Assumes all SNPs are neutral and unlinked. | |
fastsimcoal2 (Excoffier et al. 2013) | SFS from one population or the joint frequency spectrum from multiple populations; calculated from neutral polymorphisms | Likelihood of demographic model is calculated using coalescent simulations | Assumes all SNPs are neutral and unlinked. | |
Positive selection | ||||
|---|---|---|---|---|
Method | Data | Definition | Demography | As used in |
SweepFinder (Nielsen et al. 2005) | SFS from whole-genome data of one population | For each location in the genome, calculates the likelihood of the observed data under a selective sweep to the likelihood under neutrality. Outputs a composite likelihood ratio (CLR) test statistic. To determine significance, neutral simulations are performed under an inferred demographic model. | Calculates a null SFS from the background SFS, rather than from a strictly equilibrium neutral model | |
SweeD (Pavlidis et al. 2013) | SFS from whole genome data of one population | Computationally improved version of SweepFinder | Same as above | |
SweepFinder2 (DeGiorgio et al. 2016) | SFS from whole-genome data of one population | Uses statistical framework of SweepFinder, but accounts for local reductions in diversity caused by purifying selection | Same as above | Pfeifer et al. 2018 |
ω-statistic (Kim and Nielsen 2004) | SNP data | Calculates the likelihood of the observed data under a selective sweep to the likelihood under neutrality, based on patterns of linkage disequilibrium associated with genetic hitchhiking. To determine significance, neutral simulations are performed under an inferred demographic model. | Demography is not directly accounted for - though demographic simulations should be performed to obtain a neutral distribution of the statistic for comparison to data. | Poh et al. 2014 |
Fst scan | Allele frequency data from at least two populations | Measures genetic differentiation between populations in sliding genomic windows | Implicitly assumes that populations have the same effective population size and are derived independently from the same ancestral population. | |
HapFLK (Fariello et al. 2013) | Genome-wide SNPs from at least two populations and a population kinship matrix | Calculates a global measure of differentiation for each SNP (FLK) or inferred haplotype (HapFLK) after rescaling frequencies using a population kinship matrix. Genetic differentiation around a selected variant is expected to be larger than expected under drift alone. | Incorporates hierarchical population structure; demographic simulations should be performed to obtain a neutral distribution of the statistic for comparison to data | Pfeifer et al. 2018 |