Formulation of Competition Between Sexual and Selfing Forms

Abstract

In a recent issue, Rausch and Morgan (2005) analyzed the role of selfing in the autopolyploidization process theoretically based on the formulation of Felber (1991), although they did not explicitly model a pollen pool. This paper reformulates the male contribution to outcrossing in terms of gamete frequencies within a pollen pool. This is a general issue when considering competition between sexual and selfing or asexual forms in a single population, which must be considered in theoretical treatments.

Formulation of Competition Between Sexual and Selfing Forms: A Response to Yamauchi

“…We agree with Yamauchi (2006) that Rausch and Morgan (2005) implicitly assume pollen limitation. We offer here additional commentary on our original formulation, the extension offered by Yamauchi (2006), and the biological context of self-pollination.In our model, a fraction of the ovules available for outcrossing remains unfertilized, and this fraction increases with the selfing rate. Yamauchi (2006) proposes that this occurs when there is both pollen discounting (Harder and Wilson 1998) and outcross pollen limitation (Knight et al 2005).…”

“…We agree with Yamauchi (2006) that Rausch and Morgan (2005) implicitly assume pollen limitation. We offer here additional commentary on our original formulation, the extension offered by Yamauchi (2006), and the biological context of self-pollination.…”

“…In contrast to pollen limitation, pollen discounting erodes the advantage to selfing (analogous to Nagylaki 1976;Wells 1979; Holsinger et al 1984). Our analysis of Yamauchi's (2006) model shows that, in his model, t crit always equals ½: complete pollen discounting exactly eliminates the reproductive advantage to higher selfing, regardless of cytotype selfing rates.Our model and the modification provided by Yamauchi (2006) anticipate that selfing facilitates autotetraploid establishment, especially when higher selfing and/or lower inbreeding depression are present in autotetraploids. Rausch and Morgan's (2005) model is appropriate when pollen limitation occurs, and provides conditions that are conducive to…”

“…Our model and the modification provided by Yamauchi (2006) anticipate that selfing facilitates autotetraploid establishment, especially when higher selfing and/or lower inbreeding depression are present in autotetraploids. Rausch and Morgan's (2005) model is appropriate when pollen limitation occurs, and provides conditions that are conducive to…”

“…We offer here additional commentary on our original formulation, the extension offered by Yamauchi (2006), and the biological context of self-pollination.…”