DOI: 10.5061/dryad.n4mm0
title: Data from: Rapid evolution of reproductive isolation between incipient outcrossing and selfing Clarkia species

description: A major goal of speciation research is to understand the processes
 involved in the earliest stages of the evolution of reproductive
 isolation. One important challenge has been to identify systems where
 lineages have very recently diverged and opportunities for hybridization
 are present. We conducted a comprehensive examination of the components of
 reproductive isolation across the life cycle of two subspecies of Clarkia
 xantiana, which diverged recently (ca. 65,000 bp). One subspecies is
 primarily outcrossing, but self-compatible, whereas the other is primarily
 selfing. The subspecies co-occur in a zone of sympatry but hybrids are
 rarely observed. Premating barriers resulted in nearly complete isolation
 in both subspecies with flowering time and pollinator preference (for the
 outcrosser over the selfer) as the strongest barriers. We found that the
 outcrosser had consistently more competitive pollen, facilitating
 hybridization in one direction, but no evidence for pollen-pistil
 interactions as an isolating barrier. Surprisingly, postzygotic isolation
 was detected at the stage of hybrid seed development, but in no subsequent
 life stages. This crossing barrier was asymmetric with crosses from the
 selfer to outcrosser most frequently failing. Collectively, the results
 provide evidence for rapid evolution of multiple premating and postzygotic
 barriers despite a very recent divergence time.
description: Ecogeography
 populations_Briscoe Runquist et alThis file contains all
 known populations of both subspecies of Clarkia xantina. The file also
 contains numbers assigned to the populations used in manuscripts, a short
 description of the site and UTM coordinates (Zone 11S).F1 pollen viab and
 pollen prod_Briscoe Runquist et alThis file contains
 pollen counts and pollen viability determinations for both parental
 subspecies and F1 reciprocal hybrids from greenhouse grown plants. Pollen
 was counted for 2 aliquots and summed.F1 polle viab and pollen
 prod_Briscoe Runquist et al .csvF1 seed viab_Briscoe
 Runquist et alThis file contains the
 number of viable seeds (germinated + tetrazolium) for parental and F1
 reciprocal crosses. FOr each fruit we assessed 20
 seeds.F1-growth_Briscoe
 Runquist et alIn this file, we have
 the growth of parentals and F1 reciprocal crosses from a greenhouse common
 garden. We counted the number of fully formed leaves on plants at the
 beginning of the initial growth phase and then 2 weeks later. Growth was
 determined by the number of leaves added. Plants were in different blocks
 which were measured on different days (noted).Gametophyte_comp_Briscoe
 Runquist et alWe performed crosses
 using intra- and intersubspecific pollen (alternating the first pollen
 donor subspecies identity) in the greenhouse. We then counted the number
 of offspring that were hybrid from the total.Phenology Data and RI
 calcs_Briscoe Runquist et alThis file contains the
 phenological and reproductive isolation calculations (using Sobel and Chen
 2014) for each site at 4 different sites. We walked semi-permanent
 transects at each site for the flowering season and counted the number of
 flowers of each subspecies on the date noted.Pollen tube
 growth_Briscoe Runquist et alWe performed intra- and
 intersubspecific crosses in a greenhouse for 2 sympatric populations of
 Clarkia xantiana. We applied single-donor pollen and noted the time that
 we pollinated and the time at which we fixed the style (4-6 hours). We
 then measured the length of the longest pollen tube and the length of the
 style and used the data to obtain growth rates and proportional
 distance.Pollinator_transitions-constancy_Briscoe Runquist et alThis file contains all of the pollinator bouts that contained intersubspecific transitions in pollinator arrays of greenhouse grown sympatric plants that were placed out into the field. We noted the number of visits to each subspecies. We also noted the different numbers of each transition type. Transition categories are detoed "from_to" (i.e. "x_p" transition was from a xantiana to a parviflora). We also noted that parviflora may have different colors (pp = pink; wp = white; up = unknown) and the should sum to the category with only a "p". We also have separate entries using all flowers or plants only (no geitnogamy). The entries with all flowers used end in "_f".Pollinator-pref-data_Briscoe Runquist et alIn pollinator arrays of greenhouse grown plants in the field, we watched plants in the arrays (position) and at each observation time noted the number of visits to a flower subspecies and the number of each type of flower subspecies. The file also contains information on the date of observation, the observer, and whether the observation took place in the morning or afternoon.Single-donor crosses_Briscoe Runquist et alWe performed intra- and intersubspecific crosses in sympatric populations (crosses were only within populations) or allopatric populations (crosses were preformed in all combinations of all allopatric populations). There were 4 crosstypes (treatments) (1 = xantiana to xantiana), 2 = xantiana to parviflora; 3 = parviflora to xantiana; 4 = parviflora to parviflora). We counted the number of fully formed seeds, number of fertilized but aborted ovules, and the number of unfertilized ovules for each fruit collected.