How “simple” methodological decisions affect interpretation of population structure based on reduced representation library DNA sequencing: a case study using the lake whitefish

Reduced representation (RRL) sequencing approaches (e.g., RADSeq, genotyping by sequencing) require decisions about how much to invest in genome coverage and sequencing depth (library quality), as well as choices of values for adjustable bioinformatics parameters. To empirically explore the importance of these “simple” decisions, we generated two independent sequencing libraries for the same 142 individual lake whitefish (Coregonus clupeaformis) using a nextRAD RRL approach: (1) A small number of loci and low sequencing depth (library A); and (2) more loci and higher sequencing depth (library B). The fish were selected from populations with different levels of expected genetic subdivision. Each library was analyzed using the STACKS pipeline followed by three types of population structure assessment (FST, DAPC and ADMIXTURE) with iterative increases in the stringency of sequencing depth and missing data requirements, as well as more specific a priori population maps. Library B was always...