Data from: Evolution of haploid selection in predominantly diploid organisms

Diploid organisms manipulate the extent to which their haploid gametes
experience selection. Animals typically produce sperm with a diploid
complement of most proteins and RNA, limiting selection on the haploid
genotype. Plants, however, exhibit extensive expression in pollen, with
actively transcribed haploid genomes. Here we analyze models that track
the evolution of genes that modify the strength of haploid selection to
predict when evolution intensifies and when it dampens the “selective
arena” within which male gametes compete for fertilization. Considering
deleterious mutations, evolution leads diploid mothers to strengthen
selection among haploid sperm/pollen, because this reduces the mutation
load inherited by their diploid offspring. If, however, selection acts in
opposite directions in haploids and diploids (“ploidally antagonistic
selection”), mothers evolve to reduce haploid selection to avoid
selectively amplifying alleles harmful to their offspring. Consequently,
with maternal control, selection in the haploid phase either is maximized
or reaches an intermediate state, depending on the deleterious mutation
rate relative to the extent of ploidally antagonistic selection. By
contrast, evolution generally leads diploid fathers to mask mutations in
their gametes to the maximum extent possible, whenever masking (e.g.,
through transcript sharing) increases the average fitness of a father’s
gametes. We discuss the implications of this maternal–paternal conflict
over the extent of haploid selection and describe empirical studies needed
to refine our understanding of haploid selection among seemingly diploid
organisms.