DOI: 10.5061/dryad.cz8w9ghzr
title: Patterns of hybrid seed inviability in perennials of the Mimulus guttatus sp. complex reveal a potential role of parental conflict in reproductive isolation

description: Genomic conflicts may play a central role in the evolution of reproductive
 barriers. Theory predicts that early-onset hybrid inviability may stem
 from conflict between parents for resource allocation to offspring. Here
 we describe M. decorus; a group of cryptic species within the M. guttatus
 species complex that are largely reproductively isolated by hybrid seed
 inviability (HSI). HSI between M. guttatus and M. decorus is common and
 strong, but populations of M. decorus vary in the magnitude and
 directionality of HSI with M. guttatus. Patterns of HSI between M.
 guttatus and M. decorus, as well as within M. decorus conform to the
 predictions of parental conflict: firstly, reciprocal F1s exhibit size
 differences and parent-of-origin specific endosperm defects, secondly the
 extent of asymmetry between reciprocal F1 seed size is correlated with
 asymmetry in HSI, and lastly, inferred differences in the extent of
 conflict predict the extent of HSI between populations. We also find that
 HSI is rapidly evolving, as populations that exhibit the most HSI are each
 others’ closest relative. Lastly, while all populations are largely
 outcrossing, we find that the differences in the inferred strength of
 conflict scale positively with p, suggesting that demographic or life
 history factors may influence the rate of parental conflict driven
 evolution. Overall, these patterns suggest the rapid evolution of
 parent-of-origin specific resource allocation alleles coincident with HSI
 within and between M. guttatus and M. decorus. Parental conflict may
 therefore be an important evolutionary driver of reproductive isolation.
description: This submission contains 2 data files: 1)
 Patterns_of_HSI_Mdecorus_guttatus.xlsx Patterns of
 hybrid seed inviability, germination and seed size for crosses between 19
 populations of M. decorus and 1-5 populations of M. guttatus. Column
 names: Mat= maternal genotype, Pat=
 paternal genotype, rep= plate replicate for germination assay,
 cross.type=interspecific or intraspecific cross- D= M. decorus, G=M.
 guttatus, maternal parent is listed first. dec.clade=genetic lineage of M.
 decorus, total.germ= total number of seeds germinated (out of 20),
 percent.germ=the percentage of seeds germinated, average germ=average
 germination across replicate plates for that specific
 cross. 2)
 Patterns_of_HSI_WithinMdecorus.xlsx Patterns of hybrid
 seed inviability and seed size for crosses between all populations of M.
 decorus and 2 focal populations: one from the northern diploid clade
 (IMP), and one from the southern diploid clade (Odell Creek). Column
 names: Mat= maternal genotype, Mat.Rep=
 maternal plant replicate for that popultion, Pat= paternal genotype,
 Pat.Rep= paternal plant replicate for that popultion, cross.type= the type
 of cross performed, maternal parent is listed first (codes are as follows:
 P=4x decorus, S=southern decorus, N=northern decorus, O=Odell Creek-
 'southern focal individual')), clade= is the cross between
 southern M. decorus or involving tetraploids ("South" or
 "4x", respectively), total seeds= total seeds produced, viable
 looking= number of seeds that appear viable, inviable looking= number of
 seeds appearing inviable, prop.viable= proportion viable seeds
 produced. Missing data have
 been replaced with "NA".