Measuring reproductive barriers between groups of organisms is an effective way to determine the traits and mechanisms that impede gene flow. However, to understand the ecological and evolutionary factors that drive speciation, it is important to distinguish between the barriers that arise early in the speciation process and those that arise after speciation is largely complete. In this paper we comprehensively test for reproductive isolation between recently diverged (< 10,000 years bp) dune and non-dune ecotypes of the prairie sunflower, Helianthus petiolaris. We find reproductive barriers acting at multiple stages of hybridization, including premating, postmating-prezygotic, and postzygotic barriers, despite the recent divergence. Barriers include extrinsic selection against immigrants and hybrids, a shift in pollinator assemblage, and post-pollination assortative mating. Together these data suggest that multiple barriers can be important for reducing gene flow in the earliest stages of speciation.
2012_RT_Plots
The number of seedlings that emerged and survived in each subplot of our 2012 reciprocal transplant in which we planted dune, non-dune and hybrid seeds into a site in the dunes and a site in the non-dune habitat (sand sheet) at Great Sand Dunes National Park and Preserve.
2012_RT_Plants_full
Data (height, day to first flower, number of seeds, etc) for each plant that survived in our 2012 reciprocal transplant
2012_RT_Aster
Data (emergence, survival, number of flowers, number of seeds) for each seed planted in our 2012 reciprocal transplant formatted for an ASTER analysis
2012_RT_FT_survival
The period during which each plant that survived in our 2012 reciprocal transplant flowered (formatted for a survival analysis)
2012_Timelapse_FT_numbers
The number of flowers photographed by 8 timelapse cameras (DG4, DG5, Updune, 1363, 2001, NDG2, NDG3, NDG4) each day. Cameras DG4 and DG5 were in the same site, which is called DRT. Cameras NDG2, NDG3 and NDG4 were in the same site, which is called NRT. See Fig S1 for site information.
2012_Pollinators
Collection information and (morpho)species identifications for potential pollinators collected at Great Sand Dunes National Park and Preserve
2014_PCO_genoytpes_full
The number of offspring with particular genotypes (NN, NC or CC) that resulted from pollinations with mixtures of dune and non-dune pollen (dune pollen contributes "C" alleles and non-dune pollen contributes "N" alleles)
2014_Seed_set
The number of seeds set after pollinating 30 stigmas on dune and non-dune maternal plants with either dune pollen or non-dune pollen
2014_PCO_6and12_genotypes
The number of offspring fathered by dune or non-dune pollen after different pollination treatments (1 = dune pollen applied 12 hours before non-dune pollen, 2 = dune pollen applied 6 hours before non-dune pollen, 3 = dune and non-dune pollen applied together, 4 = non-dune pollen applied 6 hours before dune pollen, 5 = non-dune pollen applied 12 hours before dune pollen)
2014_Germination
Data on whether seeds from crosses made within and between dune and non-dune ecotypes (in the greenhouse in 2014) germinated
Hybrid_pollen
Data on the viability of pollen produced by dune, non-dune and hybrid plants
2014_Seed_Size_Common_Garden
The weight of seeds produced by dune and non-dune maternal plants pollinated with dune and non-dune pollen
2010_RT
The number of seedlings that emerged in each subplot of our 2010 reciprocal transplant in which we planted dune, non-dune and intermediate (collected at the boundary between dune and non-dune habitat) seeds into a site in the dunes and a site in the non-dune habitat (sand sheet) at Great Sand Dunes National Park and Preserve.
2010_RT_long
Data (emergence, survival, height, number of flowers, head diameter) for each seed planted in our 2010 reciprocal transplant
2011_RT
The number of seedlings that emerged in each subplot of our 2011 reciprocal transplant in which we planted dune and non-dune seeds into a site in the dunes and a site in the non-dune habitat (sand sheet) at Great Sand Dunes National Park and Preserve.
2011_Germination
Data on whether seeds from crosses made within and between dune and non-dune ecotypes (in the field in 2011) and seeds from open pollinated plants germinated
2008_Populations
Latitude and longitude information for each population used in this study
GSD_Barriers_Rcode
The R code used to produce each statistical analysis and figure presented in this manuscript. The code is presented in the same order that the analyses are presented in the manuscript.