Effects of Pollen Competition on Progeny Performance in a Heterozygous Cucurbit

Abstract

We used an F1 hybrid of zucchini and its wild progenitor to examine the effects of pollen competition on progeny performance. We experimentally varied the intensity of pollen competition by depositing large or small pollen loads onto stigmas. To separate the effects of pollen competition from maternal effects, we excised the styles of flowers receiving the large pollen loads after only the fastest pollen tubes had entered the ovary. The styles from flowers receiving small pollen loads were excised after both fast- and slow-growing tubes had entered the ovary. Consequently, the mature fruits from the two treatments were similar in seed number and weight. Because our previous studies had revealed that fast- and slow-growing pollen tubes fertilize ovules in different regions (locations) within the ovary (fast into region I and slow into region 3), we examined the vigor of the progeny produced in regions I and 3 from both large and small pollen loads. The results revealed that the progeny from large pollen loads outperform progeny from small pollen loads. We also found that for small pollen loads, the progeny from region I outperform the progeny from region 3, which indicates that the progeny produced by the fastest pollen tubes outperform the progeny produced from the slowest.

Self- and cross-pollination effects on pollen tube growth and seed set in holm oak Quercus ilex L (Fagaceae)

“…Differences in pollen attrition between pollination types provided evidence of pollenstyle interactions. These interactions have been shown in studies of self-incompatibility or when self-pollen is compatible but disadvantaged (Levin, 1975;Casper et al, 1988;Montalvo, 1992) or for some species in which the pollen exhibits a varying performance depending upon the recipient (Gawel and Robacker, 1986;Waser et al, 1987;Quesada et al, 1993).…”

Pollen–pollen interactions in Betula pendula in vitro

“…If there is positive correlation between the intensity of pollen competition and the performance of progeny, as many research results actually indicate (e.g. Stephenson, Winsor & Schlichting, 1988 ;Richardson & Stephenson, 1992 ;Janse & Verhaegh, 1993 ;Quesada, Winsor & Stephenson, 1993 ;Bjo$ rkman, 1995), the more intense competition between pollen grains would be an advantage to the ' female ' component of reproduction. By contrast, intense competition might not be beneficial to the male element of reproduction, which makes this kind of evolutionary explanation for positive pollenpollen interactions improbable.…”

Effectiveness of ants as pollinators of Lobularia maritima: effects on main sequential fitness components of the host plant

“…In fact, between-pollinator differences in pollen load deposited per visit result in differences in seed set mainly when ovule number per flower is high and, consequently, the ratio between pollen load delivered by pollinators and ovule number is low (Mulcahy et al 1983;McDade and Davidar 1984;Herrera 1987;Mitchell 1997a;Gómez and Zamora 1999). In contrast, when this ratio is high because ovule number per flower is low, the differences among pollinators in pollen deposited may cause no differences in seed production, but rather in progeny vigor due to intense gametophytic and zygotic competition (Snow 1986;Schlichting et al 1990;Quesada et al 1993;Mitchell 1997aMitchell , 1997b.…”