Pollen Competition, Nonrandom Fertilization, and Progeny Fitness: A Reply to Charlesworth

Stephenson, Andrew G.; Winsor, James A.; Schlichting, Carl D.; Davis, L. E.

doi:10.1086/284853

Cited by 26 publications

(9 citation statements)

References 26 publications

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“…While the relationship between pollen load size and progeny performance is well documented in the literature, the cause of this relationship has engendered much debate because variation in pollen load size simultaneously creates (1) variation in the intensity of pollen competition for access to ovules, (2) differences in maternal effects associated with differences in the number, size and location of the seeds within the ovary and (3) differences in the opportunity for non-random seed abortion (e.g. Mulcahy 1979;Charlesworth andCharlesworth 1987, 1992;Charlesworth 1988;Stephenson et al 1988b;Schlichting et al 1990;Stephenson et al 1995). This study used the techniques developed by Quesada et al (1993Quesada et al ( , 1996a for cultivars of Cucurbita to dissociate differences in the intensity of pollen competition (selection) from differences in the number, size and location of seeds within the fruit independently from differences in the opportunity for non-random seed abortion.…”

Section: Resultsmentioning

confidence: 99%

“…(2) few studies adequately control for maternal effects associated with differences in seed mass, seed number and location of the seeds within the ovary, or for postzygotic selection on developing seeds and (3) many of the studies use cultivated species as model systems (see Charlesworth 1988;Stephenson et al 1988b;Lyons et al 1989;Schlichting et al 1990;Snow 1990). …”

Section: Introductionmentioning

confidence: 99%

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Effects of pollination intensity on the vigor of the sporophytic and gametophytic generation of Cucurbita texana

Jóhannsson

Stephenson

1997

Sexual Plant Reproduction

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We examined the effects of pollen competition (pollen load size) on sporophytic vigor and gametophytic performance in Cucurbita texana, a wild gourd, while controlling for alternative interpretations of the data. Under field conditions we compared the vigor of progeny produced from large and small pollen loads and examined the in vitro performance of the pollen produced by the progeny. We found that the progeny from large pollen loads germinated faster and had a greater reproductive output (male flowers and fruits) than progeny produced from small pollen loads. In addition, we found that the pollen produced on plants derived from large pollen loads grew faster in vitro than the pollen produced on plants derived from small pollen loads. These findings indicate that pollen competition affects the performance of the resulting sporophytic generation and the microgametophytes they produce.& k w d : Key words Cucurbita texana · Pollen · Pollen performance · Pollen competition& b d y :

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of pollination intensity on the vigor of the sporophytic and gametophytic generation of Cucurbita texana

Jóhannsson

Stephenson

1997

Sexual Plant Reproduction

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“…Delph, Weinig, and Sullivan (1998) have hypothesized that it is the order of fertilization rather than speed of pollen tube growth that affects the vigor of the resulting progeny because the ovules fertilized early are better provisioned by the maternal plant than later fertilized ovules. Many studies show that faster growing pollen tubes fertilize ovules in different regions in the ovary than slower growing pollen tubes (Marshall and Ellstrand, 1988;Stephenson, Winsor, and Schlichting, 1988;Rocha and Stephenson, 1991), and it has been suggested that different regions in the ovary might have nutritional advantages, which, in turn, could lead to increased vigor in progeny (Stephenson, Winsor, and Schlichting, 1988). The eliminating of maternal effects by comparing the progeny resulting from small and large pollen loads in different regions of the ovary, as was done by Quesada, Winsor, and Stephenson (1993), does not rule out the possibility that high pollen loads alone may stimulate the maternal parent to allocate more resources to seeds and fruits.…”

Section: Discussionmentioning

confidence: 99%

Do pollen donors with fastest‐growing pollen tubes sire the best offspring in an anemophilous tree, Betula pendula (Betulaceae)?

Pasonen¹,

Pulkkinen²,

Käpylä

2001

American J of Botany

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The relationship between pollen and progeny performance has been a subject of many studies but the evidence for pollen-tube growth rate as an indicator of progeny fitness is equivocal. We used an anemophilous tree, Betula pendula, to examine the relationship between pollen-tube growth rate and seed and seedling performance. We crossed nine maternal plants with pollen from six pollen donors in a clonal B. pendula seed orchard, measured the pollen-tube growth rates for every cross, and analyzed the performance of the resulting seeds and seedlings. The only significant positive correlation was found between pollen-tube growth rate and seed mass when we controlled for seed number per inflorescence. Using seed mass as a covariate, we found that only maternal parent had a significant effect on the number of seeds per inflorescence, the percentage of germinable and embryonic seeds, and early seedling growth. Both maternal and paternal parents had significant effects on seedling height after 85 d of growth. These results are in concordance with the general view that maternal effects are usually most apparent in seed characters and during early plant growth. This study does not provide strong evidence for the theory of pollen-tube growth rate as an indicator of progeny quality.

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“…On the other hand, the relatively large stigmatic capacity of cactus flowers (up to five orders of magnitude of pollen grains can be held potentially on one stigma) guarantees the reception of enough pollen grains to fertilize most ovules. The deposition of large amounts of pollen on the stigmatic surface may promote male gametophytic competition (Stephenson and Bertin, 1983;Snow, 1986) between pollen grains from the same individual or different individuals and may possibly select for male gametophytes with higher rates of pollen tube growth (Cruden, 1977;Mulcahy, 1979;Feinsinger, 1987;Schlichting et al, 1987;Stephenson et al, 1988). If the amount of pollen deposited by bats on floral stigmas were high enough to promote sexual selection, then the service of this pollen vector could be interpreted as promoting fitter offspring.…”

Section: Discussionmentioning

confidence: 99%

Comparative pollination biology of Venezuelan columnar cacti and the role of nectar‐feeding bats in their sexual reproduction

Nassar

Ramírez

Linares

1997

American J of Botany

126

112

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The floral biology, reproductive system, and visitation behavior of pollinators of four species of columnar cacti, Stenocereus griseus, Pilosocereus moritzianus, Subpilocereus repandus, and Subpilocereus horrispinus, were studied in two arid zones in the north of Venezuela. Our results support the hypothesis that Venezuelan species of columnar cacti have evolved toward specialization on bat pollination. Additional information on the floral biology of a fifth species, Pilosocereus lanuginosus, was also included. All species showed the typical traits that characterize the pollination syndrome of chiropterophily. All species but Pilosocereus moritzianus were obligate outcrossers. Nectar and pollen were restricted to nocturnal floral visitors. Two species of nectar-feeding bats, Leptonycteris curasoae Miller and Glossophaga longirostris Miller, were responsible for practically all the fruit set in these cacti. Frequency of bat visitation per flower per night was highly variable within and between species of cactus, with average frequencies varying between 27 and 78 visits/flower/night. In general terms, the pattern of floral visitation through the night was significantly correlated with the pattern of nectar production and nectar sugar concentration for all species of cactus. Under natural pollination, fruit:flower ratios varied from 0.46 in Subpilocereus repandus to 0.76 in Stenocereus griseus. The efficiency of bat pollination in terms of seed:ovule ratio was high in all species, varying between 0.70 and 0.94.

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Pollen Competition, Nonrandom Fertilization, and Progeny Fitness: A Reply to Charlesworth

Cited by 26 publications

References 26 publications

Effects of pollination intensity on the vigor of the sporophytic and gametophytic generation of Cucurbita texana

Effects of pollination intensity on the vigor of the sporophytic and gametophytic generation of Cucurbita texana

Do pollen donors with fastest‐growing pollen tubes sire the best offspring in an anemophilous tree, Betula pendula (Betulaceae)?

Comparative pollination biology of Venezuelan columnar cacti and the role of nectar‐feeding bats in their sexual reproduction

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