Joy Avritt - Academia.edu (original) (raw)
Papers by Joy Avritt
Annals of botany, 2010
Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environment... more Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environmental factors vary. As flowers age, flower condition and amount of pollen donated and received also vary. These internal and external changes are significant for fitness if they result in changes in reproduction and mating. Literature from several fields was reviewed to provide a picture of the changes that occur in plants and flowers that can affect mating over a season. As flowers age, both the entire flower and individual floral whorls show changes in appearance and function. Over a season, changes in mating often appear as alteration in seed production vs. pollen donation. In several species, older, unpollinated flowers are more likely to self. If flowers are receiving pollen, staying open longer may increase the number of mates. In wild radish, for which there is considerable information on seed paternity, older flowers produce fewer seeds and appear to discriminate less among pollen d...
Annals of botany, 2005
Plastic responses to stress in components of reproduction can have important effects on plant fit... more Plastic responses to stress in components of reproduction can have important effects on plant fitness and can vary both within and between species. Responses may also depend on when in the life cycle stress occurs. Here, it is predicted that the timing of initiation of a stress, defoliation, would affect the pattern of plastic responses. These differences should occur because some components of reproduction, such as flower number, are determined earlier in a plant's life than others, such as individual seed mass. To test this prediction, 50 % artificial defoliation treatments were initiated at four different times for Sesbania macrocarpa and S. vesicaria. Responses were measured in plant size, number of flowers, number of flowers/plant size, fruit set, number of seeds per fruit, individual seed mass and total seed mass per plant. For S. vesicaria, changes in the timing of stress changed the severity, but not the pattern of response. For S. macrocarpa, plastic responses to defoli...
American Journal of Botany, 2000
A critical concern in the debate over the importance of sexual selection in plants is whether the... more A critical concern in the debate over the importance of sexual selection in plants is whether the nonrandom mating demonstrable in greenhouse crosses can occur in the field. Field populations likely experience smaller and more variable pollen load sizes than those that have been used in many greenhouse experiments. Therefore, we performed a greenhouse experiment in which we varied both pollen load size and composition in wild radish, Raphanus sativus, and examined the paternity of seeds. We used five maternal plants and four pairs of pollen donors. We were able to produce pollen loads of 40, 118, and 258 grains per stigma. The smallest of the pollen loads was scant enough to result in a slight, but significant reduction in seed number per fruit. While variation in pollen load composition significantly affected the proportions of seeds fathered by different donors, variation in pollen load size did not. The relative performance of different donors was constant across pollen load sizes, suggesting that, for this species, differential performance of pollen donors can occur at pollen load sizes that are likely to occur in field populations.
American Journal of Botany, 2007
When more pollen is present on stigmas than needed to fertilize all ovules, selection among polle... more When more pollen is present on stigmas than needed to fertilize all ovules, selection among pollen grains may occur due to effects of both pollen donors and maternal plants. We asked whether increasing plant age and flower age, two changes in maternal condition, altered the pattern of seed paternity after mixed pollination. We also asked whether changes in seed paternity affected offspring success in an experimental garden. While flower age did not affect seed paternity, there was a dramatic shift in pollen donor performance as plants aged. These differences were seen in the offspring as well, where the offspring of one pollen donor, which sired more seeds on young plants, flowered earlier in the season, and the offspring of another pollen donor, which sired more seeds on old plants, flowered later in the season. Thus, change in maternal condition resulted in altered seed paternity, perhaps because the environment for pollen tube growth was different. The pattern of seed paternity and offspring performance suggests that pollen donors may show temporal specialization.
![Research paper thumbnail of Pollen performance of Raphanus sativus (Brassicaceae) declines in response to elevated [CO2]](https://attachments.academia-assets.com/43210248/thumbnails/1.jpg)
](Sexual Plant Reproduction, Jun 19, 2010
Although increases in atmospheric [CO 2 ] are known to affect plant physiology, growth and reprod... more Although increases in atmospheric [CO 2 ] are known to affect plant physiology, growth and reproduction, understanding of these effects is limited because most studies of reproductive consequences focus solely on female function. Therefore, we examined the effects of CO 2 enrichment on male function in the annual Raphanus sativus. Pollen donors grown under elevated [CO 2 ] initially sired a higher proportion of seeds per fruit than ambient [CO 2 ]-grown plants when each was tested against two different standard competitors; however, by the end of the 5-month experiment, these pollen donors sired fewer seeds than ambient [CO 2 ]-grown plants and produced a lower proportion of viable pollen grains. The results of this experiment confirm that elevated [CO 2 ] can alter reproductive success. Additionally, the change in response to elevated [CO 2 ] over time varied among pollen donor families; thus, changes in [CO 2 ] could act as a selective force on this species.
Annals of botany, 2010
Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environment... more Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environmental factors vary. As flowers age, flower condition and amount of pollen donated and received also vary. These internal and external changes are significant for fitness if they result in changes in reproduction and mating. Literature from several fields was reviewed to provide a picture of the changes that occur in plants and flowers that can affect mating over a season. As flowers age, both the entire flower and individual floral whorls show changes in appearance and function. Over a season, changes in mating often appear as alteration in seed production vs. pollen donation. In several species, older, unpollinated flowers are more likely to self. If flowers are receiving pollen, staying open longer may increase the number of mates. In wild radish, for which there is considerable information on seed paternity, older flowers produce fewer seeds and appear to discriminate less among pollen d...
Annals of botany, 2005
Plastic responses to stress in components of reproduction can have important effects on plant fit... more Plastic responses to stress in components of reproduction can have important effects on plant fitness and can vary both within and between species. Responses may also depend on when in the life cycle stress occurs. Here, it is predicted that the timing of initiation of a stress, defoliation, would affect the pattern of plastic responses. These differences should occur because some components of reproduction, such as flower number, are determined earlier in a plant's life than others, such as individual seed mass. To test this prediction, 50 % artificial defoliation treatments were initiated at four different times for Sesbania macrocarpa and S. vesicaria. Responses were measured in plant size, number of flowers, number of flowers/plant size, fruit set, number of seeds per fruit, individual seed mass and total seed mass per plant. For S. vesicaria, changes in the timing of stress changed the severity, but not the pattern of response. For S. macrocarpa, plastic responses to defoli...
American Journal of Botany, 2000
A critical concern in the debate over the importance of sexual selection in plants is whether the... more A critical concern in the debate over the importance of sexual selection in plants is whether the nonrandom mating demonstrable in greenhouse crosses can occur in the field. Field populations likely experience smaller and more variable pollen load sizes than those that have been used in many greenhouse experiments. Therefore, we performed a greenhouse experiment in which we varied both pollen load size and composition in wild radish, Raphanus sativus, and examined the paternity of seeds. We used five maternal plants and four pairs of pollen donors. We were able to produce pollen loads of 40, 118, and 258 grains per stigma. The smallest of the pollen loads was scant enough to result in a slight, but significant reduction in seed number per fruit. While variation in pollen load composition significantly affected the proportions of seeds fathered by different donors, variation in pollen load size did not. The relative performance of different donors was constant across pollen load sizes, suggesting that, for this species, differential performance of pollen donors can occur at pollen load sizes that are likely to occur in field populations.
American Journal of Botany, 2007
When more pollen is present on stigmas than needed to fertilize all ovules, selection among polle... more When more pollen is present on stigmas than needed to fertilize all ovules, selection among pollen grains may occur due to effects of both pollen donors and maternal plants. We asked whether increasing plant age and flower age, two changes in maternal condition, altered the pattern of seed paternity after mixed pollination. We also asked whether changes in seed paternity affected offspring success in an experimental garden. While flower age did not affect seed paternity, there was a dramatic shift in pollen donor performance as plants aged. These differences were seen in the offspring as well, where the offspring of one pollen donor, which sired more seeds on young plants, flowered earlier in the season, and the offspring of another pollen donor, which sired more seeds on old plants, flowered later in the season. Thus, change in maternal condition resulted in altered seed paternity, perhaps because the environment for pollen tube growth was different. The pattern of seed paternity and offspring performance suggests that pollen donors may show temporal specialization.
Sexual Plant Reproduction, Jun 19, 2010
Although increases in atmospheric [CO 2 ] are known to affect plant physiology, growth and reprod... more Although increases in atmospheric [CO 2 ] are known to affect plant physiology, growth and reproduction, understanding of these effects is limited because most studies of reproductive consequences focus solely on female function. Therefore, we examined the effects of CO 2 enrichment on male function in the annual Raphanus sativus. Pollen donors grown under elevated [CO 2 ] initially sired a higher proportion of seeds per fruit than ambient [CO 2 ]-grown plants when each was tested against two different standard competitors; however, by the end of the 5-month experiment, these pollen donors sired fewer seeds than ambient [CO 2 ]-grown plants and produced a lower proportion of viable pollen grains. The results of this experiment confirm that elevated [CO 2 ] can alter reproductive success. Additionally, the change in response to elevated [CO 2 ] over time varied among pollen donor families; thus, changes in [CO 2 ] could act as a selective force on this species.