The Experts below are selected from a list of 8379 Experts worldwide ranked by ideXlab platform
Johan Ehrlén - One of the best experts on this subject based on the ideXlab platform.
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flowering schedule in a perennial plant life history trade offs Seed Predation and total offspring fitness
Ecology, 2015Co-Authors: Johan Ehrlén, Jana Raabova, Johan P DahlgrenAbstract:Optimal timing of reproduction within a season may be influenced by several abiotic and biotic factors. These factors sometimes affect different components of fitness, making assessments of net selection difficult. We used estimates of offspring fitness to examine how pre-dispersal Seed Predation influences selection on flowering schedule in an herb with a bimodal flowering pattern, Actaea spicata. Within individuals, Seeds from flowers on early terminal inflorescences had a higher germination rate and produced larger Seedlings than Seeds from flowers on late basal inflorescences. Reproductive value, estimated using demographic integral projection models and accounting for size-dependent differences in future performance, was two times higher for intact Seeds from early flowers than for Seeds from late flowers. Fruits from late flowers were, however, much more likely to escape Seed Predation than fruits from early flowers. Reproductive values of early and late flowers balanced at a Predation intensity of 63%. Across 15 natural populations, the strength of selection for allocation to late flowers was positively correlated with mean Seed Predation intensity. Our results suggest that the optimal shape of the flowering schedule, in terms of the allocation between early and late flowers, is determined by the trade-off between offspring number and quality, and that variation in antagonistic interactions among populations influences the balancing of this trade-off. At the same time they illustrate that phenotypic selection analyses that fail to account for differences in offspring fitness might be misleading.
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ecological and evolutionary consequences of spatial and temporal variation in pre dispersal Seed Predation
Perspectives in Plant Ecology Evolution and Systematics, 2007Co-Authors: Annette Kolb, Johan Ehrlén, Ove ErikssonAbstract:Abstract Pre-dispersal Seed Predation may have important effects on population dynamics and trait evolution in plants. In this review, we first present a conceptual framework of the strength of pre-dispersal Seed Predation and its variation in space and time. We consider the interaction between plants and their Seed predators to be “strong” when it affects plant population dynamics or causes changes in plant trait–fitness relationships, and “weak” when it has no such effects, and propose ways of how to adequately assess these effects. Second, we review the ecological literature between 1991 and 2005 to evaluate documented effects of pre-dispersal Seed Predation on plants and draw five major conclusions. (1) Pre-dispersal Seed Predation rates are usually low but sometimes high, and show a considerable variation in space and time. (2) Direct evidence suggests that pre-dispersal Seed Predation can have a significant effect on recruitment and plant population growth rate. Accumulating evidence of Seed-limited recruitment suggests that such effects are common. (3) Pre-dispersal Seed Predation affects selection on several plant traits, such as flowering phenology and flower number, which are usually interpreted mainly in the context of plant–pollinator interactions. (4) The patterns of variation in the interactions between plants and pre-dispersal Seed predators suggest that geographic selection mosaics may be common. (5) Although there are numerous studies estimating Seed Predation, there are still rather few studies that have aimed at examining the interaction explicitly in terms of effects on plant population dynamics and trait selection. From these we know that Seed predators can have important, and often variable, effects on plant population dynamics and trait evolution. However, it still remains to assess how important they are across study systems and relative to other aspects of the plant's biotic and abiotic environment.
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among population variation in specialist and generalist Seed Predation the importance of host plant distribution alternative hosts and environmental variation
Oikos, 2005Co-Authors: Hannah Östergård, Johan EhrlénAbstract:Among population variation in specialist and generalist Seed Predation - the importance of host plant distribution, alternative hosts and environmental variation
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pollen limitation Seed Predation and scape length in primula farinosa
Oikos, 2002Co-Authors: Johan Ehrlén, Sofia Kack, Jon AgrenAbstract:Floral display and reward production may affect the attractiveness of a plant to a range of interacting animals including pollinators, herbivores, and vectors of pathogenic fungi. The optimal floral phenotype should therefore depend on the relative importance of selection exerted by both mutualistic and antagonistic animals. The perennial, rosette herb Primula farinosa is polymorphic for scape length. Natural populations may include both plants with flowers displayed well above the ground (the long-scaped morph) and those with flowers positioned very close to the ground (the short-scaped morph). In this study, we conducted a field experiment to examine how the relative fitness of the two scape morphs is affected by interactions with pollinators and fruit predators in two different microhabitats (high and low vegetation). As predicted based on the difference in floral display, supplemental hand-pollination showed that fruit initiation was more strongly pollen-limited in the short-scaped than in the long-scaped morph, and that this difference was significantly larger in high than in low vegetation. Moreover, plants with a short scape experienced lower levels of fruit Predation than plants with a long scape. Among open-pollinated controls, there was no significant difference in Seed output between the two scape morphs. However, among plants receiving supplemental hand-pollination, short-scaped plants produced significantly more Seeds than long-scaped plants. The results suggest that the positive and negative effects of a prominent floral display (increased pollination and Seed Predation, respectively) balance in the study population, but also that the short-scaped morph would have an advantage at higher pollination intensities. Spatial and temporal variation in pollinator activity and Seed Predation should result in associated variation in the relative fecundity of the two scape morphs.
Bo Wang - One of the best experts on this subject based on the ideXlab platform.
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Seed density affects post dispersal Seed Predation evidence from a Seed removal experiment of 62 species
Integrative Zoology, 2020Co-Authors: Bo WangAbstract:Post-dispersal Seed Predation plays an important role in plant demography and biodiversity maintenance. However, the effects of Seed density on Seed Predation from previous studies have been inconsistent. We dissected the effects of density on the 2-step processes of Seed Predation using 101 520 Seeds from 62 plant species in an alpine pine forest for 3 consecutive years. In this study we explained the current controversy surrounding the effects of density on Seed Predation. Seed encounter frequency (at least 1 Seed being predated from an experiment depot) showed positive density dependence, while Seed exploitation (the proportion of Seeds being predated of the encountered depots) showed negative density dependence. Both density effects showed a consistent trend but with different magnitudes of effect across years. Final Seed Predation is the combination of Seed encounter and Seed exploitation. Final Seed Predation could be either positively or negatively density-dependent and was contingent on the magnitude of the difference between positive density-dependent Seed encounter and negative density-dependent Seed exploitation. Our results also indicated that studies including only a few species would produce biased results, because the density effect on Seed Predation differed greatly among plant species. Future studies should include a large number of plant species that possess a wide range of diverse Seed traits to avoid potential bias and produce more comprehensive and accurate results.
Fernando Cornejo - One of the best experts on this subject based on the ideXlab platform.
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Seed Predation on Brazil Nuts (Bertholletia excelsa) by Macaws (Psittacidae) in Madre de Dios, Peru
Biotropica, 2004Co-Authors: Mandar R. Trivedi, Fernando Cornejo, Andrew R. WatkinsonAbstract:We investigated the impact of Seed Predation by large macaws (Ara spp.) on Brazil nut, the Seed of Bertholletia excelsa (Lecythidaceae). Counts of macaw-damaged fruit below 50 focal trees in a Peruvian Brazil nut harvesting concession indicated that macaws destroyed about 10 percent of the concession's crop. We compared this impact to other sources of variation in profits from harvesting and suggest methods to compensate harvesters while encouraging them to conserve macaws in their concessions.
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effect of distance aggregation and habitat on levels of Seed Predation for two mammal dispersed neotropical rain forest tree species
Oecologia, 1996Co-Authors: Evan Notman, David L Gorchov, Fernando CornejoAbstract:The effect of Seed aggregation and distance from conspecific trees on Seed Predation was experimentally examined for two neotropical tree species, Macoubea guianensis (Apocynaceae) and Pouteria sp. (Sapotaceae) in a lowland tropical rain forest in northeastern Peru. Results of these experiments are discussed in the context of the Janzen-Connell model (Janzen 1970; Connell 1971), which predicts decreased Seed survival near parent trees due to either density-or distance-responsive mortality, and Howe's model (Howe 1989) which predicts that trees with Seeds dispersed in clumps (aggregated) will not suffer density-dependent Predation, and will have higher survival of Seeds near the parent tree than other trees. We also examined whether Predation on Seeds of these species was affected by Seed placement in or near 30-m-wide strips regenerating after clear-cutting. Both species appeared to be mammal-dispersed but differed in how frugivores handled Seeds, Seed size, overall fruit crop size, and gemination time. Neither of the two species studied appeared to suffer Seed Predation in a manner predicted by the Janzen-Connell model, and patterns of Seed Predation for only one of the species was similar to predictions of Howe's model. For neither species did Seed Predation along the edge of, or in the center of, regenerating clear cuts differ from Predation 15 m into the primary forest. For Pouteria, Seed Predation in and near regnerating strips was significantly greater than around forest trees, but the opposite pattern held for Macoubea. Overall, Seed Predation was much greater on Macoubea. The difference in Seed Predation for these two species was most likely a result of differences in the types of Seed predators that attacked these two species.
Cesar A Dominguez - One of the best experts on this subject based on the ideXlab platform.
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Pre-dispersal Seed Predation reduces the reproductive compensatory advantage of thrum individuals in Erythroxylum havanense (Erythroxylaceae)
Evolutionary Ecology, 2008Co-Authors: Karina Boege, Cesar A DominguezAbstract:Male-sterility mutations in hermaphroditic species represent the first step in the evolution of gender specialization. Male-sterile individuals commonly compensate the loss of the male function by increasing the number or quality of Seeds. Because the magnitude of compensation determines the maintenance of females within populations and the evolution of sexual specialization, plant-animal interactions may affect these evolutionary processes if animals are sensitive to such reproductive asymmetries. Here we explore the effect of Seed Predation on the reproductive compensation of Erythroxylum havanense , a distylous shrub with morph-biased partial male sterility, during two consecutive years. Seed Predation reduced the compensatory advantage of thrums in 1987, but not in 1988. Annual differences in the intensity of Seed Predation seem to be accounted for differences in the onset and synchrony of flowering. Thus, although Seed predators may reduce the compensatory advantage of thrums, their impact is modulated by the environmental cues triggering flowering and insect emergence.
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simulated Seed Predation reveals a variety of germination responses of neotropical rain forest species
American Journal of Botany, 2006Co-Authors: Mario Vallejomarin, Cesar A Dominguez, Rodolfo DirzoAbstract:Seed Predation, an omnipresent phenomenon in tropical rain forests, is an important determinant of plant recruitment and forest regeneration. Although Seed Predation destroys large amounts of the Seed crop of numerous tropical species, in many cases individual Seed damage is only partial. The extent to which partial Seed Predation affects the recruitment of new individuals in the population depends on the type and magnitude of alteration of the germination behavior of the damaged Seeds. We analyzed the germination dynamics of 11 tropical woody species subject to increasing levels of simulated Seed Predation (0–10% Seed mass removal). Germination response to Seed damage varied considerably among species but could be grouped into four distinct types: (1) complete inability to germinate under damage � 1%, (2) no effect on germination dynamics, (3) reduced germination with increasing damage, and (4) reduced final germination but faster germination with increasing damage. We conclude that partial Seed Predation is often nonlethal and argue that different responses to Predation may represent different proximal mechanisms for coping with partial damage, with potential to shape, in the long run, morphological and physiological adaptations in tropical, large-Seeded species.
Philip E Hulme - One of the best experts on this subject based on the ideXlab platform.
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post dispersal Seed Predation consequences for plant demography and evolution
Perspectives in Plant Ecology Evolution and Systematics, 1998Co-Authors: Philip E HulmeAbstract:Abstract Post-dispersal Seed Predation is only one of many factors underlying plant demography and evolution. Nevertheless, the generalist feeding habits of many post-dispersal Seed predators and the limited ability of plants either to compensate for or to respond to post-dispersal Seed losses directly suggest that post-dispersal Seed Predation may have a considerable impact on plant populations. Seed predators probably have little direct influence on the demography of plants that regenerate exclusively by vegetative means or are buffered by a large active Seed bank, but such species are only a minority in most plant communities. In general, ants are significant post-dispersal Seed predators in arid and semi-arid ecosystems while they act mainly as Seed dispersers rather than as predators in temperate ecosystems. Although studies have probably underestimated the importance of invertebrates and birds as Seed predators, rodents appear to have greater potential to influence Seed dynamics, and are particularly important in temperate ecosystems. For example, production of mast Seed crops is more effective at satiating specialist invertebrate Seed predators than generalist vertebrates, and recruitment may be limited by post-dispersal Seed Predation even during mast years. Both spatial variation in post-dispersal Seed Predation and differences in Predation between species are important elements which facilitate the coexistence of different plant species. Where microsites are limiting, selective post-dispersal Seed predators can influence pre-emptive competition for these microsites. Seed size determines the extent of density-dependent Predation and the exploitation of buried Seed. This suggests that post-dispersal Seed predators may also play a role in the evolution of Seed characteristics. However, conclusions regarding the ecological and evolutionary impact of post-dispersal Seed predators will remain speculative without a more substantial empirical base.
