Figure 1.

Two Key Questions Should Guide Future Research on Gametophytic Selection.

Three approaches can be used to determine the prevalence of gametophytic selection:

(A) Investigate gene-expression overlap between the gametophyte and sporophyte.

(B) Reverse genetics: evaluate the impact of genetic knockouts on gametophytes.

(C) Forward genetics: scan genome-wide for associations between alleles and gametophyte phenotypes (GWAS).

To evaluate the effects of gametophytic selection on sporophytes, the following studies will be useful:

(D) Use the allele frequency spectrum (AFS) to compare the frequency of alleles with effects on gametophyte fitness to neutral expectations.

(E) Conduct artificial selection on gametophytes to evaluate the impact on the sporophyte (see, e.g. Domínguez et al., 2005 on selection for cold tolerance in tomatoes).

(F) Use linked neutral genetic diversity to infer signals of past selection.