Data from: Reduced genetic diversity and increased reproductive isolation follow population-level loss of larval dispersal in a marine gastropod

Population-level consequences of dispersal ability remain poorly understood, especially for marine animals in which dispersal is typically considered a species-level trait governed by oceanographic transport of microscopic larvae. Transitions from dispersive (planktotrophic) to non-dispersive, aplanktonic larvae are predicted to reduce connectivity, genetic diversity within populations, and the spatial scale at which reproductive isolation evolves. However, larval dimorphism within a species is rare, precluding population-level tests. We show the sea slug Costasiella ocellifera expresses both larval morphs in Florida and the Caribbean, regions with divergent mitochondrial lineages. Planktotrophy predominated at 11 sites, 10 of which formed a highly connected and genetically diverse Caribbean metapopulation. Four populations expressed mainly aplanktonic development and had markedly reduced connectivity, and lower genetic diversity at one mitochondrial and six nuclear loci. Aplanktonic dams showed partial post-zygotic isolation in most inter-population crosses, regardless of genetic or geographic distance to the sire's source, suggesting outbreeding depression affects fragmented populations. Dams from genetically isolated and neighboring populations also exhibited pre-mating isolation, consistent with reinforcement contingent on historical interaction. By increasing self-recruitment and genetic drift, the loss of dispersal may thus initiate a feedback loop resulting in the evolution of reproductive isolation over small spatial scales in the sea.01, C_ocellifera master COI dataMaster spreadsheet showing COI haplotype codes, NCBI accession numbers, sampling frequency per location, and specimen identifiers for slugs with a given haplotype02, Coce_COI_Evolution2015Nexus file of collapsed COI haplotypes, with BayesPhylogenies command block03, Arlequin input file, Coce_13_popsArlequin input file for COI haplotypic data, each sampling site separated04, Coce_COI_CaribP_run1BEAST input files for generating Bayesian skyline plot of pooled Caribbean planktotrophic demes05, Coce_LAK_COI_run1BEAST input files for generating Bayesian skyline plot of Lake Surprise population06, Coce_GEI_COI_run1BEAST input files for generating Bayesian skyline plot of Geiger Beach population07, Coce_LSS_COI_run1BEAST input files for generating Bayesian skyline plot of Little San Salvador population08, Coce_Plana_COI_run1BEAST input files for generating Bayesian skyline plot of Plana Cays population09, Coce_msats_14popsArlequin input file for microsatellite data, each sampling site separated10, Coce_msats.strStructure input file for microsatellite data11, 4runs_Coce_COI_post_burnin.nexTree file combining post-burnin output from four Bayesian analyses of COI dat