Data from: Unidirectional diploid–tetraploid introgression among British birch trees with shifting ranges shown by restriction site-associated markers
Hybridization may lead to introgression of genes among species. Introgression may be bidirectional or unidirectional, depending on factors such as the demography of the hybridizing species, or the nature of reproductive barriers between them. Previous microsatellite studies suggested bidirectional i...
Main Authors: | , , , , , , |
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Format: | Dataset |
Language: | unknown |
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Dryad
2016
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Subjects: | |
Online Access: | https://doi.org/10.5061/dryad.815rj https://doi.org/10.5061/dryad.815rj.1 https://doi.org/10.5061/dryad.815rj.2 |
Summary: | Hybridization may lead to introgression of genes among species. Introgression may be bidirectional or unidirectional, depending on factors such as the demography of the hybridizing species, or the nature of reproductive barriers between them. Previous microsatellite studies suggested bidirectional introgression between diploid Betula nana (dwarf birch) and tetraploid B. pubescens (downy birch) and also between B. pubescens and diploid B. pendula (silver birch) in Britain. Here, we analyse introgression among these species using 51 237 variants in restriction site-associated (RAD) markers in 194 individuals, called with allele dosages in the tetraploids. In contrast to the microsatellite study, we found unidirectional introgression into B. pubescens from both of the diploid species. This pattern fits better with the expected nature of the reproductive barrier between diploids and tetraploids. As in the microsatellite study, introgression into B. pubescens showed clear clines with increasing introgression from B. nana in the north and from B. pendula in the south. Unlike B. pendula alleles, introgression of B. nana alleles was found far from the current area of sympatry or allopatry between B. nana and B. pubescens. This pattern fits a shifting zone of hybridization due to Holocene reduction in the range of B. nana and expansion in the range of B. pubescens. Genotyping method (mixed ploidy dataset)This script allows the genotyping of a mixed ploidy data set (including polyploids). It is based on read counts and average base quality. The algorithm calculates the most likely variant configuration at each locus using a log-likelihood model.genotyping.RBeta-binomial model for allelic ratiosFunction to model number of reads per SNP allele as a mixture of beta-binomial distributions. The data are censored to be between two cutoff values.betabinomial.RPlotting of figuresCollection of scripts used for plotting figures in the present study.plotting.RAnalyses used in present studyCollection of scripts used for analyses in ... |
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