Assessment of individual costs of the anti-predator defence translating into changes in population parameters is meagre.This is because prey responses are likely to be modulated by additional factors,commonly present ...Assessment of individual costs of the anti-predator defence translating into changes in population parameters is meagre.This is because prey responses are likely to be modulated by additional factors,commonly present in the environment,but often neglected in experimental studies.To evaluate the effect of external factors on prey behavior and physiology,we exposed amphipods Dikerogammarus villosus and Gammarus jazdzewskii to the predation cue of Perca fluviatilis in different densities and light conditions.Singletons of both species exposed to the predation cue in light modified their oxygen consumption(D.villosus:reduction,G.jadzewskii:increase)compared to their respiration in predator-free conditions.However,in the presence of conspecifics or in darkness,their respiration became insensitive to the predation cue.On the other hand,the swimming activity of prey was reduced in the presence of the predation cue irrespective of prey density and light conditions,but singletons were consistently more active than groups.Thus,external factors,such as conspecifics and darkness,constantly or periodically occurring in the field,may reduce the costs of predator non-consumptive effects compared to the costs measured under laboratory conditions(in light or absence of conspecifics).Moreover,we showed that behavioral and physiological parameters of prey may change differently in response to predation risk.Thus,conclusions drawn on the basis of single defence mechanisms and/or results obtained in artificial conditions,not reflecting the environmental complexity,strongly depend on the experimental design and endpoint selection and therefore should be treated with care.展开更多
Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Intera...Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Interactions(i)between plants and insect herbivores and(I)between plants and mycorrhizal fungi are ubiquitous in terrestrial ecosystems and may be linked via common host plants.Previous studies suggest that colonization by arbuscular mycorrhizal fungi(AMF)can modifty plants'induced responses to herbivore attack,but these indirect effects of fungal symbionts are poorly understood.I investigated the role of AMF in induced plant response to a gen-eralist herbivore.Methods|manipulated AMF status and herbivory in Cucumis sativus L.(cucumber,Cucurbitaceae)in a greenhouse to investigate induced responses in the presence and absence of the mycorrhi-zal fungus Glomus intraradices(Glomeraceae).Spodoptera exigua Habner(Noctuidae)were used to manipulate prior damage and later as assay caterpillars.I also measured G.intraradices and her-bivory effects on plant N and effects on plant growth.Impor tant Findings AMF status affected the induced response of C.sativus,underscor-ing the importance of incorporating the roles of plant symbionts into plant defense theory.Assay caterpillars ate significantly more leaf tissue only on mycorrhizal plants that had experienced prior damage.Despite more consumption,biomass change in these cat-erpillars did not differ from those feeding on plants with other treat-ment combinations.Leaf N content was reduced by G.intraradices but unaffected by herbivory treatments,suggesting that the observed differences in assay caterpillar feeding were due to changes in defensive chemistry that depended on AMF.展开更多
Beyond direct species interactions,seed dispersal is potentially affected by indirect seed–seed interactions among co-occurring nut-bearing trees which are mediated by scatter-hoarding animals as shared seed disperse...Beyond direct species interactions,seed dispersal is potentially affected by indirect seed–seed interactions among co-occurring nut-bearing trees which are mediated by scatter-hoarding animals as shared seed dispersers.A relevant question in such systems is to what extent different functional traits related to food palatability and profitability affect the kinds of indirect interactions that occur among co-occurring seeds,and the consequences for seed dispersal.We used field experiments to track seed dispersal with individually tagged seeds in both monospecific and mixed seed communities.We measured indirect effects based on 3 seed–seed species pairs from the family Fagaceae with contrasting seed size,tannin level,and dormancy in a subtropical forest in Southwest China.When all else was equal,the presence of adjacently placed seeds with contrasting seed traits created different indirect effects measured through a variety of dispersal-related indicators.Apparent mutualism was reciprocal due to increasing seed dispersal in mixed seed patches with mixed differences in seed tannins and dormancy.However,differences in either seed size or dormancy in co-occurring adjacently placed seeds caused apparent competition with reduced seed removal or seed dispersal(distance)in at least one species.Our study supports the hypothesis that different functional traits related to food palatability and profitability in co-occurring seeds modify foraging decisions of scatter-hoarding animals,and subsequently cause indirect effects on seed dispersal among rodent-dispersed trees.We conclude that such indirect effects mediated by shared seed dispersers may act as an important determinant of seed dispersal for co-fruiting animal-dispersed trees in many natural forests.展开更多
基金Our study was supported by the grants of the National Science Centre,Poland No.2016/21/B/NZ8/00418 and 2020/39/D/NZ8/01226.
文摘Assessment of individual costs of the anti-predator defence translating into changes in population parameters is meagre.This is because prey responses are likely to be modulated by additional factors,commonly present in the environment,but often neglected in experimental studies.To evaluate the effect of external factors on prey behavior and physiology,we exposed amphipods Dikerogammarus villosus and Gammarus jazdzewskii to the predation cue of Perca fluviatilis in different densities and light conditions.Singletons of both species exposed to the predation cue in light modified their oxygen consumption(D.villosus:reduction,G.jadzewskii:increase)compared to their respiration in predator-free conditions.However,in the presence of conspecifics or in darkness,their respiration became insensitive to the predation cue.On the other hand,the swimming activity of prey was reduced in the presence of the predation cue irrespective of prey density and light conditions,but singletons were consistently more active than groups.Thus,external factors,such as conspecifics and darkness,constantly or periodically occurring in the field,may reduce the costs of predator non-consumptive effects compared to the costs measured under laboratory conditions(in light or absence of conspecifics).Moreover,we showed that behavioral and physiological parameters of prey may change differently in response to predation risk.Thus,conclusions drawn on the basis of single defence mechanisms and/or results obtained in artificial conditions,not reflecting the environmental complexity,strongly depend on the experimental design and endpoint selection and therefore should be treated with care.
基金U.S.Department of Agriculture(NRI 2008-02346)Northern Illinois University Department of Biological Sciencesthe Northern Illinois University Institute for the Study of the Environment,Sustainability,and Energy.
文摘Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Interactions(i)between plants and insect herbivores and(I)between plants and mycorrhizal fungi are ubiquitous in terrestrial ecosystems and may be linked via common host plants.Previous studies suggest that colonization by arbuscular mycorrhizal fungi(AMF)can modifty plants'induced responses to herbivore attack,but these indirect effects of fungal symbionts are poorly understood.I investigated the role of AMF in induced plant response to a gen-eralist herbivore.Methods|manipulated AMF status and herbivory in Cucumis sativus L.(cucumber,Cucurbitaceae)in a greenhouse to investigate induced responses in the presence and absence of the mycorrhi-zal fungus Glomus intraradices(Glomeraceae).Spodoptera exigua Habner(Noctuidae)were used to manipulate prior damage and later as assay caterpillars.I also measured G.intraradices and her-bivory effects on plant N and effects on plant growth.Impor tant Findings AMF status affected the induced response of C.sativus,underscor-ing the importance of incorporating the roles of plant symbionts into plant defense theory.Assay caterpillars ate significantly more leaf tissue only on mycorrhizal plants that had experienced prior damage.Despite more consumption,biomass change in these cat-erpillars did not differ from those feeding on plants with other treat-ment combinations.Leaf N content was reduced by G.intraradices but unaffected by herbivory treatments,suggesting that the observed differences in assay caterpillar feeding were due to changes in defensive chemistry that depended on AMF.
基金This research was supported by the National Key Research and Development Program of China(2016YFC0500105,2017YFC0503802)the National Natural Science Foundation of China(31971441,31770565)The State Key Laboratory of IntegratedManagement of Pest Insects and Rodents(ChineseIPM1718).
文摘Beyond direct species interactions,seed dispersal is potentially affected by indirect seed–seed interactions among co-occurring nut-bearing trees which are mediated by scatter-hoarding animals as shared seed dispersers.A relevant question in such systems is to what extent different functional traits related to food palatability and profitability affect the kinds of indirect interactions that occur among co-occurring seeds,and the consequences for seed dispersal.We used field experiments to track seed dispersal with individually tagged seeds in both monospecific and mixed seed communities.We measured indirect effects based on 3 seed–seed species pairs from the family Fagaceae with contrasting seed size,tannin level,and dormancy in a subtropical forest in Southwest China.When all else was equal,the presence of adjacently placed seeds with contrasting seed traits created different indirect effects measured through a variety of dispersal-related indicators.Apparent mutualism was reciprocal due to increasing seed dispersal in mixed seed patches with mixed differences in seed tannins and dormancy.However,differences in either seed size or dormancy in co-occurring adjacently placed seeds caused apparent competition with reduced seed removal or seed dispersal(distance)in at least one species.Our study supports the hypothesis that different functional traits related to food palatability and profitability in co-occurring seeds modify foraging decisions of scatter-hoarding animals,and subsequently cause indirect effects on seed dispersal among rodent-dispersed trees.We conclude that such indirect effects mediated by shared seed dispersers may act as an important determinant of seed dispersal for co-fruiting animal-dispersed trees in many natural forests.
