DOI: 10.5061/dryad.g4f4qrfz4
title: Data from: Translocation precipitates natural hybridisation and pervasive introgression between marine gastropods with divergent developmental modes

description: Assisted colonisation, the introduction of species beyond their historical
 range, is increasingly necessary for conserving species. However,
 empirical evidence of the long-term genetic outcomes of assisted
 colonisation is grossly lacking. A risk associated with moving species
 beyond their native range is the possibility of interspecific
 hybridisation with a closely related species, potentially
 resulting in outbreeding depression or the genetic
 swamping of a parental species. Here, we use a combination of
 genome-wide Single Nucleotide Polymorphism (SNP) markers
 and mitochondrial DNA sequencing to determine the long-term genetic
 consequences of introducing the intertidal periwinkle Bembicium
 vittatum (a direct developer) beyond its native range and into
 the native range of its congener Bembicium auratum (a
 species with planktotrophic larval dispersal). We found novel evidence of
 natural, multigenerational hybridisation between marine invertebrates with
 different modes of development.
 Intriguingly, introgression was highly asymmetrical
 initially, but became more evenly bidirectional as the population became
 more admixed. There was a significant decline in the frequency of alleles
 from the introduced B. vittatum over time, providing
 evidence of genetic swamping. The present study also provides potential
 evidence of outbreeding depression, in the form of cytonuclear
 incompatibilities, leading to the observed pattern of
 asymmetrical introgression. This study reveals the potential for
 unexpected mixing between species when reproductive barriers are not well
 understood, resulting in failure of pure B. vittatum to
 persist at the translocation site, a major concern associated with
 assisted colonisation. Without long-term genetic monitoring interspecific
 hybridisation between B. vittatum and B.
 auratum would have gone undetected, highlighting the importance of
 long-term monitoring to detect unintentional negative consequences of
 conservation translocations. Successful assisted colonisation requires an
 understanding of the potential for interspecific hybridisation between the
 threatened species and closely related native species, to reduce the risk
 of adverse outcomes.
description: # Translocation precipitates natural hybridisation and pervasive
 introgression between marine gastropods with divergent developmental modes
 [https://doi.org/10.5061/dryad.g4f4qrfz4](https://doi.org/10.5061/dryad.g4f4qrfz4) ## Description of the data and file structure "Report_DBemb21-6115_2_SNP_mapping_2.csv" contains raw SNP genotype data generated by Diversity Arrays Technology for each individual used in the study. Each allele is scored in binary fashion ("1"=Presence and "0"=Absence) and heterozygotes are scored as 1/1 (presence for both alleles/both rows). Locus metatdata is also contained in this file (generated by DArT) including allele identification (AlleleID), the seaquence of each allele (AlleleSequence), average count of the reference (AvgCountRef) and SNP allele (AvgCountSnp), average polymorphism content of each locus (AvgPIC), locus call rate (CallRate), a unique identifier for the sequence that each SNP occurs in (CloneID), the proportion of samples scored as heterozygotes for each locus (FreqHets), the proportion of samples scored as homozygous for the reference allele (FreqHomRef) and SNP allele (FreqHomSnp), the polymorphism information content for the reference allele (PICRef) and the SNP allele (PICSnp), the proportion of technical replicates where the marker score is consistent (RepAvg), the position within the sequence tag where the SNP occurs (SnpPosition), and a trimmed version of the full sequence, but with adapters removed in shorter marker tags (TrimmedSequence). "metadata_dryad.xlsx" contains individual metadata, including individual identification, population code, year collected, latitude, longitude, species classification and haplotype information based on 12S sequences for individuals collected in Fremantle and the B. vittatum and B. auratum source populations. Haplotype information was not obtained from B. auratum individuals from Albany or Rocky Bay as it was not relevant to the study and haplotype information is missing for some individuals collected from Fremantle due to an insufficient amount of DNA left by that stage in the project. In these cases, columns "Species haplotype", "Haplotype" and "GenBank Accession" have been left blank. "Hybridisation_manuscript_analyses_dryad.R" contains the code used to conduct all analyses for this study and "Hybridisation_manuscript_figures_dryad.R" contains the code used to create all figures.