DOI: 10.5061/dryad.6p8p0
title: Data from: Reproductive isolation and introgression between sympatric Mimulus species

description: Incompletely isolated species provide an opportunity to investigate the
 genetic mechanisms and evolutionary forces that maintain distinct species
 in the face of ongoing gene flow. Here, we use field surveys and reduced
 representation sequencing to characterize the patterns of reproductive
 isolation, admixture and genomic divergence between populations of the
 outcrossing wildflower Mimulus guttatus and selfing M. nasutus. Focusing
 on a single site where these two species have come into secondary contact,
 we find that phenological isolation is strong, although incomplete, and is
 likely driven by divergence in response to photoperiod. In contrast to
 previous field studies, which have suggested that F1-hybrid formation
 might be rare, we discover patterns of genomic variation consistent with
 ongoing introgression. Strikingly, admixed individuals vary continuously
 from highly admixed to nearly pure M. guttatus, demonstrating ongoing
 hybridization and asymmetric introgression from M. nasutus into M.
 guttatus. Patterns of admixture and divergence across the genome show that
 levels of introgression are more variable than expected by chance. Some
 genomic regions show a reduced introgression, including one region that
 overlaps a critical photoperiod QTL, whereas other regions show elevated
 levels of interspecific gene flow. In addition, we observe a genome-wide
 negative relationship between absolute divergence and the local
 recombination rate, potentially indicating natural selection against M.
 nasutus ancestry in M. guttatus genetic backgrounds. Together, our results
 suggest that Mimulus speciation is both ongoing and dynamic and that a
 combination of divergence in phenology and mating system, as well as
 selection against interspecific alleles, likely maintains these sympatric
 species.
description: CAC.Mimulus.2012.phenology.by.plotThis file contains data on flowering phenology from mixed populations of Mimulus guttatus, Mimulus nasutus, and hybrids, from Catherine Creek in Wasthington State, USA during 2012. Flowering data was collected from each of 20 0.5 meter squared plots. The number of open flowers in each plot was recorded on 31 days throughout the 2012 flowering season. Each row in the datasheet is a date; plots are represented in columns. Each data point is the number of open flowers recorded within a plot on a single day. See Kenney and Sweigart 2016 for detailed information on species composition per plot.CAC.Mimulus.2013.photoperiod.experimentThis data file contains flowering data for Mimulus guttatus and Mimulus nasutus from a growthchamber, photoperiod experiment performed in 2013. Individuals from five maternal M. guttatus lines (N=11-12 per line, per treatment) and two M. nasutus lines (N=23 per line, per treatment) were grown under two daylength treatments: 12 or 16 hrs. Whether an individual flowered was recorded as yes or no after eight weeks of growth. Families were originally collected from Catherine Creek in Washington State (USA) in 2010 or 2012. Each row in the data sheet is one individual. See additional information and descriptions of their location of origin in Kenney and Sweigart 2016.