DOI: 10.5061/dryad.d3kk74r
title: Data from: Selection, drift and introgression shape MHC polymorphism in lizards

description: The Major Histocompatibility Complex (MHC) has long served as a model for
 the evolution of adaptive genetic diversity in wild populations.
 Pathogen-mediated selection is thought to be a main driver of MHC
 diversity, but it remains elusive to what degree selection shapes MHC
 diversity in complex biogeographical scenarios where other evolutionary
 processes (e.g. genetic drift and introgression) may also be acting. Here,
 we focus on two closely related green lizard species, Lacerta trilineata
 and L. viridis, to address the evolutionary forces acting on MHC diversity
 in populations with different biogeographic structure. We characterized
 MHC class I exon 2 and exon 3, and neutral diversity (microsatellites), to
 study the relative importance of selection, drift and introgression in
 shaping MHC diversity. As expected, positive selection was a significant
 force shaping the high diversity of MHC genes in both species. Moreover,
 introgression significantly increased MHC diversity in mainland
 populations, with a primary direction of gene flow from L. viridis to L.
 trilineata. Finally, we found significantly fewer MHC alleles in island
 populations, but maintained MHC sequence and functional diversity,
 suggesting that positive selection counteracted the effect of drift.
 Overall, our data support that different evolutionary processes govern MHC
 diversity in different biogeographical scenarios: positive selection
 occurs broadly while introgression acts in sympatry and drift when the
 population sizes decrease.
description: README_Sagonas_et_alReadme file containing descriptions of the files deposited for this manuscriptSpecimens_information_Sagonas_et_alA file contains the information for each specimens used in the present study. The different columns denote the collection/museum numbers (NHMC: Natural History Museum of Crete), class, family, species names and IDs, sampling regions and island names, country and accession numbers. The last two columns denotes whether sequencing was successful (i.e., 1) or not (i.e., 0) for neutral or adaptive markers (1/0). Furthermore, we report those specimens that were sequenced twice.Microsatellite_data_Sagonas_et_alA file contains the microsatellite data where the Fst-values are based on. The first column entitled Sample-ID includes the abbreviation for specimens as given in File 1.Euclidean_geographical_distances_Sagonas_et_alContains the populations Euclidean geographical distance in km. Populations abbreviations as in File 1. Mantel test and Mantel correlogram were estimated based on this matrixMHC_class_I_STRUCTURE_Sagonas_et_alContains the major histocompatibility complex (MHC) data that the estimation of the pairwise Bray-Curtis similarity matrix was based on. The presence of an allele is indicated with 1 while the absence with 0. The table contains the exon 2 and exon 3 class I alleles in STRUCTURE format.MHC_class_I_alleles_exon2_Sagonas_et_alData containing the raw MHC sequences of exon 2 for Lacerta trilineata and Lacerta viridisMHC_class_I_alleles_exon3_Sagonas_et_alData containing the raw MHC sequences of exon 2 for Lacerta trilineata and Lacerta viridis