DOI: 10.5061/dryad.64dh3
title: Data from: Disruption of endosperm development is a major cause of hybrid seed inviability between Mimulus guttatus and Mimulus nudatus

description: Divergence of developmental mechanisms within populations could lead to
 hybrid developmental failure, and might be a factor driving speciation in
 angiosperms. We investigate patterns of endosperm and embryo development
 in Mimulus guttatus and the closely related, serpentine endemic Mimulus
 nudatus, and compare them to those of reciprocal hybrid seed. We address
 whether disruption in hybrid seed development is the primary source of
 reproductive isolation between these sympatric taxa. M. guttatus and M.
 nudatus differ in the pattern and timing of endosperm and embryo
 development. Some hybrid seeds exhibit early disruption of endosperm
 development and are completely inviable, while others develop relatively
 normally at first, but later exhibit impaired endosperm proliferation and
 low germination success. These developmental patterns are reflected in
 mature hybrid seeds, which are either small and flat (indicating little to
 no endosperm) or shriveled (indicating reduced endosperm volume). Hybrid
 seed inviability forms a potent reproductive barrier between M. guttatus
 and M. nudatus. We shed light on the extent of developmental variation
 between closely related species within the M. guttatus species complex, an
 important ecological model system, and provide a partial mechanism for the
 hybrid barrier between M. guttatus and M. nudatus.
description: Growth from 1-5 days
 after pollination of immature seedsThis is a text file with
 size data from immature seeds derived self-pollination of Mimulus guttatus
 and M. nudatus accession and sympatric, reciprocal M. guttatus x M.
 nudatus hybrids. M. guttatus accessions are CSS4 and DHR14; M. nudatus
 accessions are CSH10 and DHRo22. CSS4 and CSH10 are sympatric; DHR14 and
 DHRo22 are sympatric. Hybrid seeds either exhibit endopserm development
 from 2-5 days after pollination ('Hybrid Developing') or exhibit
 arrested developing starting at 2 days after pollination ('Hybrid
 Arrested'). CSS4x = self-pollinated CSS4, etc.; DAP = days after
 pollination; UO = unfertilized ovule. Size is measured from the chalazal
 to micropylar end and is given in mm. All crosses are female x
 male.ImmatureSeedSizeCentral cell and putative primary endopserm cell widthsThis file contains measurements of the width of the central cell of Mimulus guttatus and M. nudatus accessions and of the putative primary endosperm cell of reciprocal hybrids. M. guttatus accessions are CSS4 and DHR14; M. nudatus accessions are CSH10 and DHRo22. CSS4 and CSH10 are sympatric; DHR14 and DHRo22 are sympatric. CSS4x = self-pollinated CSS4, etc.; DAP = days after pollination; UO = unfertilized ovule. Widths are measured from laser confocal images and are given in um. All crosses are female x male.CCvsPENConfocalData.csvSeed set and proportion seed type from self-pollinations and reciprocal M. guttatus x M. nudatus crossesThis file contains seed count data from self-pollinations of Mimulus guttatus and M. nudatus and sympatric, reciprocal M. guttatus x M. nudatus hybrids. In addition to total seed set, proportions of round, shriveled and flat seeds are given. M. guttatus accessions are CSS4 and DHR14; M. nudatus accessions are CSH10 and DHRo22. CSS4 and CSH10 are sympatric; DHR14 and DHRo22 are sympatric.SeedSetandProportions.csvSizes of mature seeds from self-pollinated M. guttatus and M. nudatus accessionsThis file contains sizes of the three seed morphs (round, shriveled and flat) derived from self-pollinations of Mimulus guttatus and M. nudatus accessions. M. guttatus accessions are CSS4 and DHR14. M. nudatus accessions are CSH10 and DHRo22. Size data are the length from the chalazal to micropylar end of mature seeds.SeedMorphSizeData.csv