DOI: 10.5061/dryad.72sn74q
title: Data from: Reproductive isolation and the maintenance of species boundaries 1 in two serpentine endemic Jewelflowers

description: Speciation occurs when reproductive barriers substantially reduce gene
 flow between lineages. Understanding how specific barriers contribute to
 reproductive isolation offers insight into the initial forces driving
 divergence, and the evolutionary and ecological processes responsible for
 maintaining diversity. Here we quantified multiple pre- and
 post-pollination isolating barriers in a pair of closely related
 California Jewelflowers (Streptanthus, Brassicaceae) living in an area of
 sympatry. S. breweri and S. hesperidis are restricted to similar
 serpentine habitats, however populations are spatially isolated at
 fine-scales and rarely co-occur in intermixed stands. Several intrinsic
 postzygotic barriers were among the strongest we quantified, however
 postzygotic barriers currently contribute little to overall reproductive
 isolation due to the cumulative strength of earlier-acting extrinsic
 barriers, including spatial isolation, and flowering time and pollinator
 differences. Data from multiple years suggest that pre-pollination
 barriers may have different strengths depending on annual environmental
 conditions. Similarly, crossing data suggest that the strength of
 intrinsic isolation may vary between different population pairs. Estimates
 of total reproductive isolation in S. breweri - S. hesperidis are robust
 to uncertainty and variability in individual barrier strength estimates,
 demonstrating how multiple barriers can act redundantly to prevent gene
 flow between close relatives living in sympatry.
description: data1_Spatial_isolation_dataLat/lon coordinates for all known S. breweri and S. hesperidis sites from McLaughlin Natural Reserve.data2_Phenology_data_2014Phenology data from 2014.data3_Phenology_data_2015Phenology data from 2015.data4_Phenology_data_2016Phenology data from 2016.data5_Pollinator_richness_dataPollinator richness data.data6_Pollinator_abundance_dataPollinator abundance data.data7_Crossing_dataCrossing data - used to calculate intrinsic postzygotic RI at the fruit set/fertilization and seed production life history stages.data8_F1_Viability_dataF1 viability (survival to flowering) data.data9_F1_Sterility_pollen_production_dataF1 sterility (pollen production) data.data10_F1_Sterility_backcross_dataF1 sterility data (female sterility assessed via backcrosses with F1s serving as maternal parents).Fig1b_McLauglhin_sitesData used to produce Figure 1b.Fig2_all_bootstrap_dataData used to produce Figure 2 (10,000 bootstrap samples for each isolating barrier). NOTE: "Phenology" and "F1 Sterility" barriers have multiple components.Fig3_all_bootstrap_dataData used to produce Figure 3 (10,000 bootstrap samples of RI for pre-pollination barriers in different years).Fig4_all_bootstrap_dataData used to produce Figure 4 (10,000 bootstrap samples of RI for postzygotic barriers assessed in different population pairs).Fig5_Sbreweri_cumulative_RI_dataData used to produce Figure 5 (10,000 iterations of cumulative RI for S. breweri after each isolating barrier).Fig5_Shesperidis_cumulative_RI_dataData used to produce Figure 5 (10,000 iterations of cumulative RI for S. hesperidis after each isolating barrier).