The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Rebecca E Irwin - One of the best experts on this subject based on the ideXlab platform.
-
consequences of secondary nectar robbing for Male components of Plant reproduction
American Journal of Botany, 2018Co-Authors: Rebecca E Irwin, Sarah K Richman, John T Bosak, Judith L BronsteinAbstract:PREMISE OF THE STUDY Organisms engage in multiple species interactions simultaneously. While pollination studies generally focus on Plants and pollinators exclusively, secondary robbing, a behavior that requires other species (primary robbers) to first create access holes in corollas, is common. It has been shown that secondary robbing can reduce Plants' feMale fitness; however, we lack knowledge about its impact on Male Plant fitness. METHODS We experimentally simulated primary and secondary robbing in the monocarpic perennial Ipomopsis aggregata (Polemoniaceae), quantifying indirect effects on pollinator-mediated pollen (dye) donation. We also assessed whether continual nectar removal via the floral opening has similar effects on hummingbird-pollinator behavior as continual secondary robbing through robber holes. KEY RESULTS We found no significant indirect effects of secondary robbing on a component of Ipomopsis Male fitness. Although robbing did reduce pollen (dye) donation due to avoidance of robbed Plants by pollinating hummingbirds, pollen donation did not differ between the two robbing treatments. The effects of secondary robbing on hummingbird behavior resembled effects of chronic nectar removal by pollinators. Our results indicate that hummingbird pollinators may use a combination of cues, including cues given by the presence or absence of nectar, to make foraging decisions. CONCLUSIONS Combined with prior research, this study suggests that secondary robbing is less costly to a component of Male fitness than to feMale fitness in Ipomopsis, broadening our knowledge of the overall costs of mutualism exploitation to total Plant fitness.
-
effects of florivory on Plant pollinator interactions implications for Male and feMale components of Plant reproduction
American Journal of Botany, 2016Co-Authors: Adrian L Carper, Rebecca E Irwin, Lynn S. AdlerAbstract:PREMISE OF THE STUDY Florivory could have direct negative effects on Plant fitness due to consumption of floral organs, and indirect effects mediated through changes in traits important to pollination. These effects likely vary with Plant sexual system, depending on sex- or morph-specific patterns of damage. We investigated the direct and indirect effects of simulated florivory on Male and feMale components of reproduction in the native, distylous vine Gelsemium sempervirens. METHODS We crossed floral damage and supplemental pollination treatments in a common garden array and tracked pollinator behavioral responses. We also estimated Male function using fluorescent dye as an analog for pollen transfer, and measured both fruit and seed production. KEY RESULTS The effects of floral damage varied by floral morph, the genus of floral visitor, and the component of reproduction measured. Damage reduced the number of pollinator visits to pin but not thrum Plants, and increased the time some pollinators spent per flower in thrum but not pin Plants. Flowers of damaged Plants transferred more dye particles to recipient Plants compared to undamaged Plants, but only later in the season when the majority of dye transfer occurred. Damage had no effect on feMale reproduction. CONCLUSION These results suggest that florivory can have positive indirect effects on estimated Male Plant reproduction through changes in different pollinators' behavior at flowers, but the effects of floral damage vary with Male vs. feMale function. These results underscore the importance of other species' interactions at flowers in driving pollinator behavior and pollen transfer dynamics.
-
Effects of Abiotic Factors and Species Interactions on Estimates of Male Plant Function: A Meta-Analysis
Ecology Letters, 2012Co-Authors: Robert N. Schaeffer, Jessamyn S. Manson, Rebecca E IrwinAbstract:The majority of angiosperms are hermaphroditic with total fitness comprised of both Male and feMale components of reproduction. However, most studies examining the effects of abiotic factors and species interactions on fitness have focussed on feMale reproduction, potentially biasing our understanding of the consequences of environmental factors on total fitness. Here, we use meta-analysis to test how environmental factors affect Male function. We obtained 278 effect sizes from 96 studies that measured Male function responses to manipulated environmental factors. We found significant effects of abiotic factors and species interactions on estimates of Male function, with responses varying depending on environmental factor identity. Male and feMale responses were correlated for abiotic factor manipulations, but varied based on the type of species interaction (antagonistic or mutualistic). This suggests that measuring only feMale function may misrepresent whole-Plant reproduction depending on context. Finally, we found differences amongst components of Male function in response to environmental factors, suggesting that some Male function estimates may fail to capture the effects of environmental factors on Male fitness. Our results demonstrate the importance of incorporating Male function into ecological and evolutionary studies to provide a more accurate understanding of the effects of environmental factors on total fitness.
-
beyond biomass measuring the effects of community level nitrogen enrichment on floral traits pollinator visitation and Plant reproduction
Journal of Ecology, 2010Co-Authors: Laura A. Burkle, Rebecca E IrwinAbstract:Summary 1. Nitrogen (N) limits primary productivity in many systems and can have dramatic effects on Plant–herbivore interactions, but its effects on mutualistic interactions at the community level are not well-understood. The reproduction of many Plants depends on both soil N and pollination, and N may affect floral traits, such as flower number or size, which are important for pollinator attraction to Plant individuals and communities. 2. Thus, N may influence Plant biomass and reproduction directly as well as indirectly via changes in pollination. The degree to which the effects of N enrichment scale from Plant individuals to assemblages through emerging community-level changes in species interactions, like pollination, is relatively unknown. 3. For 4 years, we tested how N addition to subalpine Plant assemblages in Colorado, USA, affected primary productivity and species diversity, floral traits and Plant–pollinator interactions, and components of feMale and Male Plant reproduction. 4. At the community level, we found that high-N addition favoured the biomass and seed production of grasses, whereas low-N addition promoted forb growth, flower production and pollinator visitation. However, using a pollen supplementation experiment, we found no evidence that N addition altered patterns of pollen limitation of seed production. Pollinators distributed themselves evenly across floral resources such that per-flower visitation rate did not differ among N treatments. Thus, individual Plants did not incur any extra benefit or cost from community-level changes in Plant–pollinator interactions that resulted from N enrichment, and the effects of N on forb reproduction were direct. 5. Synthesis. Understanding how mutualistic and antagonistic species interactions influence individual and community responses to abiotic resources may provide insight to the dominant forces structuring communities and is especially important in the context of predicting the effects of environmental change. In this case, the direct effects of N addition on Plants were stronger than the indirect effects mediated through Plant–pollinator interactions, thus supporting the concept of bottom-up resource limitation controlling Plant response.
-
Beyond biomass: measuring the effects of community‐level nitrogen enrichment on floral traits, pollinator visitation and Plant reproduction
Journal of Ecology, 2010Co-Authors: Laura A. Burkle, Rebecca E IrwinAbstract:Summary 1. Nitrogen (N) limits primary productivity in many systems and can have dramatic effects on Plant–herbivore interactions, but its effects on mutualistic interactions at the community level are not well-understood. The reproduction of many Plants depends on both soil N and pollination, and N may affect floral traits, such as flower number or size, which are important for pollinator attraction to Plant individuals and communities. 2. Thus, N may influence Plant biomass and reproduction directly as well as indirectly via changes in pollination. The degree to which the effects of N enrichment scale from Plant individuals to assemblages through emerging community-level changes in species interactions, like pollination, is relatively unknown. 3. For 4 years, we tested how N addition to subalpine Plant assemblages in Colorado, USA, affected primary productivity and species diversity, floral traits and Plant–pollinator interactions, and components of feMale and Male Plant reproduction. 4. At the community level, we found that high-N addition favoured the biomass and seed production of grasses, whereas low-N addition promoted forb growth, flower production and pollinator visitation. However, using a pollen supplementation experiment, we found no evidence that N addition altered patterns of pollen limitation of seed production. Pollinators distributed themselves evenly across floral resources such that per-flower visitation rate did not differ among N treatments. Thus, individual Plants did not incur any extra benefit or cost from community-level changes in Plant–pollinator interactions that resulted from N enrichment, and the effects of N on forb reproduction were direct. 5. Synthesis. Understanding how mutualistic and antagonistic species interactions influence individual and community responses to abiotic resources may provide insight to the dominant forces structuring communities and is especially important in the context of predicting the effects of environmental change. In this case, the direct effects of N addition on Plants were stronger than the indirect effects mediated through Plant–pollinator interactions, thus supporting the concept of bottom-up resource limitation controlling Plant response.
Scott E Nielsen - One of the best experts on this subject based on the ideXlab platform.
-
direct and indirect effects of overstory canopy and sex biased density dependence on reproduction in the dioecious shrub shepherdia canadensis elaeagnaceae
Diversity, 2020Co-Authors: Tyler J Bateman, Scott E NielsenAbstract:This study assessed the reproductive success of a temperate dioecious shrub, Canada buffaloberry, Shepherdia canadensis (L.) Nutt., in central Alberta, Canada, by examining the effects of spatial patterns and overstory canopy on flower and fruit production. S. canadensis is more abundant and productive (more fruit) at forest edges and in forest gaps, suggesting a dependence on higher light conditions than is typical of late-seral forests. We used path analysis to demonstrate that flower and fruit production exhibited density-dependent effects at a scale of 50 m2 around focal feMale Plants. Fruit production was positively affected by Male intraspecific density (pollen supply) and negatively affected by feMale intraspecific density (pollen competition), but not correlated with overall intraspecific density. The effects of sex-differentiated density are partly due to pollinator responses to Male Plant density. Flower production was positively affected by overall intraspecific density. A pollen supplementation trial doubled fruit production relative to a control, demonstrating that local Male density (pollen availability) and pollinator activity can limit fruit production in S. canadensis. Canopy cover was negatively related to both flower and total fruit production, with approximately one-third (34%) of the total effect of canopy on fruit production due to the effect of canopy on flower production. The commonly observed negative association between canopy cover and fruit production in buffaloberry, therefore, is partly a result of the reduction first in flower number and second in fruit set. This study clarifies the mechanisms associated with the often-noted observation, but not previously assessed at the level of individuals, that reproductive output in S. canadensis is density dependent, limited by canopy cover through reductions in both flowering and fruit set, and pollinator limited. These findings hold implications for managing animal species that depend on the fruit of S. canadensis and suggest future directions for research on dioecious and actinorhizal species.
-
demographic effects on fruit set in the dioecious shrub canada buffaloberry shepherdia canadensis
PeerJ, 2014Co-Authors: Kate M Johnson, Scott E NielsenAbstract:The effects of pollen limitation on reproductive success in Plants have been well-documented using pollen supplementation experiments. However, the role of local demographics in determining pollen limitation, particularly in terms of the additive and interactive effects of pollen availability and competition are not well known. We measured fruit set in the dioecious shrub Canada buffaloberry (Shepherdia canadensis) in Central Alberta, Canada to evaluate whether local demographics measured at three spatial scales (25, 50, and 100 m(2)) affect fruit set in buffaloberry. We test whether density-dependence (population density), pollen donor (measured as Male density, distance to nearest Male Plant and size of nearest Male Plant), feMale competitor (measured as feMale density and distance to nearest feMale Plant), or the combined pollen donor and competitor hypotheses best explain natural variations in fruit set for a population of Canada buffaloberry. Support was highest for the combined pollen donor and competitor hypothesis at an intermediate spatial scale of 50 m(2). Proportion fruit set increased with Male shrub density (pollen donors) and decreased with feMale shrub density (pollen competitors), but was more affected by the presence of Males than feMales. This illustrates that access to Male shrubs within a 3.99 m radius affects pollen availability, while nearby feMales compete intra-specifically for pollen.
Irene Padavic - One of the best experts on this subject based on the ideXlab platform.
-
WHITE-COLLAR WORK VALUES AND WOMEN'S INTEREST IN BLUE-COLLAR JOBS
Gender & Society, 1992Co-Authors: Irene PadavicAbstract:Based on a case study of a large utility company, this article analyzes the effect of a preference for white-collar work on women's job decisions. The sample consists of a group of women who worked temporarily in traditionally Male Plant jobs in the company and a group of women who remained in white-collar jobs in the same firm. Results indicate that both groups did indeed value job attributes that are found principally in office jobs, such as clean conditions, the chance to socialize on the job, and working with similar people, but these preferences did not significantly influence whether they would consider switching to traditionally Male Plant jobs. Much more influential were practical considerations, such as economic need. Since many women–especially ones in economic need–would find such jobs desirable, an explanation that takes into account barriers to women's entry is necessary to understand the causes of women's low representation in traditionally Male Plant jobs.
Tyler J Bateman - One of the best experts on this subject based on the ideXlab platform.
-
direct and indirect effects of overstory canopy and sex biased density dependence on reproduction in the dioecious shrub shepherdia canadensis elaeagnaceae
Diversity, 2020Co-Authors: Tyler J Bateman, Scott E NielsenAbstract:This study assessed the reproductive success of a temperate dioecious shrub, Canada buffaloberry, Shepherdia canadensis (L.) Nutt., in central Alberta, Canada, by examining the effects of spatial patterns and overstory canopy on flower and fruit production. S. canadensis is more abundant and productive (more fruit) at forest edges and in forest gaps, suggesting a dependence on higher light conditions than is typical of late-seral forests. We used path analysis to demonstrate that flower and fruit production exhibited density-dependent effects at a scale of 50 m2 around focal feMale Plants. Fruit production was positively affected by Male intraspecific density (pollen supply) and negatively affected by feMale intraspecific density (pollen competition), but not correlated with overall intraspecific density. The effects of sex-differentiated density are partly due to pollinator responses to Male Plant density. Flower production was positively affected by overall intraspecific density. A pollen supplementation trial doubled fruit production relative to a control, demonstrating that local Male density (pollen availability) and pollinator activity can limit fruit production in S. canadensis. Canopy cover was negatively related to both flower and total fruit production, with approximately one-third (34%) of the total effect of canopy on fruit production due to the effect of canopy on flower production. The commonly observed negative association between canopy cover and fruit production in buffaloberry, therefore, is partly a result of the reduction first in flower number and second in fruit set. This study clarifies the mechanisms associated with the often-noted observation, but not previously assessed at the level of individuals, that reproductive output in S. canadensis is density dependent, limited by canopy cover through reductions in both flowering and fruit set, and pollinator limited. These findings hold implications for managing animal species that depend on the fruit of S. canadensis and suggest future directions for research on dioecious and actinorhizal species.
Don W Smith - One of the best experts on this subject based on the ideXlab platform.
-
differential estrogenic activities of Male and feMale Plant extracts from two dioecious species
Plant Science, 1995Co-Authors: Camelia Gabrielaanca Maier, Kent D Chapman, Don W SmithAbstract:Abstract The reconstituted steroid transcription unit in Saccharomyces cerevisiae transformed with both a human estrogen receptor expression plasmid (YEPE10) and a reporter plasmid (YRPE2) was used to screen for estrogen compounds in cell extracts prepared from feMale and Male Plants of osage-orange, Maclura pomifera (Raf.) Scheind. and mulberry, Morus microphylla Buckl. ( Moraceae ). Phytoestrogens in the Plant extracts induced the transcription of the reporter gene in transgenic yeast. The transcriptional activity increased proportionally with increased amounts of Plant extracts added to the yeast cells. FeMale mulberry and osage-orange Plant extracts activated transcription of the steroid reporter gene about 15 times and 4 times, respectively, compared to the corresponding Male Plant extracts. The putative phytoestrogen from Maclura was lipid soluble, and co-migrated with sterols (17 β-estradiol) and isoflavones (genistein) in TLC separations. The active fractions recovered from TLC plates exhibited UV-absorption spectra similar to authentic estradiol and genistein. The putative phytoestrogen appeared to be synthesized at specific developmental stages in feMale Maclura Plants; levels of transcriptional activity were higher at times prior to and during flowering (February–April). Moreover, extracts from monoecious members of Moraceae , Ficus species (fig and rubber tree) did not activate transcription of the steroid reporter gene in the yeast system. Collectively, these data correlate the occurrence and levels of endogenous phytoestrogens with feMale individuals of two dioecious species, suggesting a possible pattern or strategy in the reproductive ecology of these dioecious species.