Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affect...Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affecting prey choice. Two methods were used, an assessment of the extent to which an individual octopus made choices of species representative of those population （PSi and IS） and 25% cutoff values for number of choices and percentage intake of individual on their prey. In one population of Octopus cfvulgaris in Bermuda individuals were generalist by IS=0.77, but most chose many prey of the same species, and were specialists on it by 〉75% intake. Another population had a wider prey selection, still generalist with PSi=0.66, but two individuals specialized by choices. In Bonaire, there was a wide range of prey species chosen, and the population was specialists by IS=0.42. Individual choices revealed seven specialists and four generalists. A population of Octopus cyanea in Hawaii all had similar choices of crustaceans, so the population was generalist by IS with 0.74. But by individual choices, three were considered a spe-cialist. A population of Enteroctopus dofleini from Puget Sound had a wide range of preferences, in which seven were also spe-cialists, IS=0.53, By individual choices, thirteen were also specialists. Given the octopus specialty of learning during foraging, we hypothesize that both localized prey availability and individual personality differences could influence the exploration for prey and this translates into different prey choices across individuals and populations showed in this study.展开更多
Micro-eukaryotic communities are highly sensitive to environmental changes, and their structure offers crucial insights into the impact of human activities on aquatic habitats. Despite their significance, the assembly...Micro-eukaryotic communities are highly sensitive to environmental changes, and their structure offers crucial insights into the impact of human activities on aquatic habitats. Despite their significance, the assembly mechanisms of micro-eukaryotic communities in lake ecosystems heavily influenced by human activities are not well understood. In this study, we utilized 18S rDNA amplicon sequencing to examine the biodiversity of micro-eukaryotes over a one-year period in Lake Weishan, one of the largest freshwater lakes in northern China. We analyzed the ecological processes governing community assembly among key ecological groups, specifically habitat generalists and specialists. Our findings revealed substantial temporal variation in microbial diversity and community composition, likely driven by water temperature, dissolved oxygen, and the concentrations of several ions (e.g., Ca^(2+) and F^(−)). Notably, community assembly in this canal-disturbed lake was predominantly influenced by stochastic processes (58.18%) rather than deterministic processes (20.46%). Habitat specialists (425 operational taxonomic units, OTUs) exhibited significantly greater diversity compared to habitat generalists (189 OTUs) and were predominantly shaped by stochastic processes (52.47%). In contrast, habitat generalists were less influenced by these processes (17.69%). Altogether, these results suggest that the ecological processes governing micro-eukaryotic community assembly differ markedly between habitat generalists and specialists, primarily due to their varied adaptability to environmental changes.展开更多
Avian species diversity in Southern Africa is remarkably high,yet the mechanisms responsible for that diversity are poorly understood.While this is particularly true with respect to species endemic to the subregion,it...Avian species diversity in Southern Africa is remarkably high,yet the mechanisms responsible for that diversity are poorly understood.While this is particularly true with respect to species endemic to the subregion,it is unclear as to how more broadly distributed African species may have colonized southern Africa.One process that may in part account for the high bird species diversity in southern Africa is a“species pump”model,wherein the region was repeatedly colonized by lineages from areas further north:a pattern related to climate cycling and the eastern African arid corridor.Once occupying southern Africa,with its many varied biomes,it is possible that climate cycling further affected lineages by generating genetic diversity in multiple refugia,a pattern recently shown for several southern African bird species.Here,we used mtDNA to address these questions in a widespread,sedentary habitat generalist bird species,the familiar chat(Oenanthe familiaris).The phylogenetic structure suggests a northto-south colonization pattern,supporting the“species pump”model.Haplotype diversity was partitioned into two distinct clusters:southern Africa and Malawi(East Africa).Southern African haplotypes were not geographically partitioned,and we hypothesize that this pattern has arisen because this species is a habitat generalist,and as such resilient to habitat-altering climate perturbations.Based on our phylogenetic results,we discuss the validity of currently recognized subspecies.展开更多
Aims The superior performance of many non-indigenous species in a new range can be attributed to different factors such as pre-adaptation to environmental conditions in new areas or to factors inherent to displacement...Aims The superior performance of many non-indigenous species in a new range can be attributed to different factors such as pre-adaptation to environmental conditions in new areas or to factors inherent to displacement mechanisms such as loss of co-evolved pathogens and herbivores that increase the speed of evolutionary change towards a shift in allocation from defence to growth and reproduction.To assess the importance of the different mechanisms governing the success of Conyza canadensis,a globally successful invader,we simultaneously tested several recent hypotheses potentially explaining the factors leading to biological invasion.Methods We tested(i)whether plants from the non-native range showed a higher fitness than plants from the native North American range,(ii)whether they differed in resistance against an invasive generalist herbivore,the slug Arion lusitanicus and against a recently established specialist aphid herbivore,Uroleucon erigeronense and(iii)experimentally assessed whether C.canadensis releases allelopathic chemicals that have harmful effects on competing species in the nonnative range.We compared populations along a similar latitudinal gradient both in the native North American and invasive European range and analysed patterns of adaptive clinal variation in biomass production.Important Findings The invasion success of C.canadensis in Europe cannot be attributed to a single trait,but to a combination of factors.Invasive plants benefited from increased growth and above all,increased reproduction(a key trait in an annual plant)and were less attacked by a co-migrated specialist enemy.The observed loss of defence against generalist slugs did not translate into a decreased fitness as invasive C.canadensis plants showed a high re-growth potential.In contrast to earlier in vitro studies,we detected no allelopathic effects on the competing flora in the non-native range.The latitudinal cline in vegetative biomass production in the non-native range observed in our common garden study indicates a high adaptive potential.However,only further genetic studies will provide conclusive evidence whether the differentiation in the non-native range is caused by pre-adaptation and sorting-out processes of putatively repeatedly introduced populations of this composite,long-distance disperser with highly volatile seeds or evolved de novo as a rapid response to new selection pressures in the nonnative range.展开更多
Successful invasions by exotic plants are often attributed to a loss of co-evolved specialists and a re-allocation of resources from defense to growth and reproduction. However, invasive plants are rarely completely r...Successful invasions by exotic plants are often attributed to a loss of co-evolved specialists and a re-allocation of resources from defense to growth and reproduction. However, invasive plants are rarely completely released from insect herbivory because they are frequently attacked by generalists in their introduced ranges. The novel generalist community may also affect the invasive plant＇s defensive strategies and resource allocation. Here, we tested this hypothesis using American pokeweed （Phytolacca americana L.）, a species that has become invasive in China, which is native to North America. We examined resistance, tolerance, growth and reproduction of plant populations from both China and the USA when plants were exposed to natural generalist herbivores in China. We found that leaf damage was greater for invasive populations than for native populations, indicating that plants from invasive ranges had lower resistance to herbivory than those from native ranges. A regression of the percentage of leaf damage against mass showed that there was no significant difference in tolerance between invasive and native populations, even though the shoot, root, fruit and total mass were larger for invasive populations than for native populations. These results suggest that generalist herbivores are important drivers mediating the defensive strategies and resource allocation of the invasive American pokeweed.展开更多
Current evidence suggests that pollen is both chemically and structurally protected. Despite increasing interest in studying bee-flower networks, the constraints for bee development related to pollen nutritional conte...Current evidence suggests that pollen is both chemically and structurally protected. Despite increasing interest in studying bee-flower networks, the constraints for bee development related to pollen nutritional content, toxicity and digestibility as well as their role in the shaping of bee-flower interactions have been poorly studied. In this study we combined bioassays of the generalist bee Bombus terrestris on pollen of Cirsium, Trifolium, Salix, and Cistus genera with an assessment of nutritional content, toxicity, and digestibility of pollen. Microcolonies showed significant differences in their development, non-host pollen of Cirsium being the most unfavorable. This pollen was characterized by the presence of quite rare 37-sterols and a low digestibility. Cirsium consumption seemed increase syrup collection, which is probably related to a detoxification mixing behavior. These results strongly suggest that pollen traits may act as drivers of plant selection by bees and partly explain why Asteraceae pollen is rare in bee generalist diet.展开更多
We investigated the performance trade-offs of fleas(Siphonaptera)while adapting to a novel host using two host generalists(Xenopsylla conformis and Xenopsylla ramesis)and one host specialist(Parapulex chephrenis)maint...We investigated the performance trade-offs of fleas(Siphonaptera)while adapting to a novel host using two host generalists(Xenopsylla conformis and Xenopsylla ramesis)and one host specialist(Parapulex chephrenis)maintained on their principal hosts(Meriones crassus for Xenopsylla and Acomys cahirinus for P.chephrenis).We asked whether,over generations,(i)a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and(ii)a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host.We established an experimental line of each species on a novel host(Acomys russatus for Xenopsylla and M.crassus for P.chephrenis)and maintained this line on this host during 23 generations.We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size,hatching success,offspring production,and offspring size.We found changes in performance over generations in female offspring size only.Xenopsylla conformis demonstrated a tendency to become a host specialist(increased performance on the novel host with a concomitant decreased performance on the original host),whereas P.chephrenis demonstrated a tendency to become a host generalist(increased performance on the novel host without a concomitant decreased performance on the original host).We conclude that the probability of generalist to specialist transition,and vice versa,is context-dependent and varies between species.展开更多
This paper studies the dynamics of the generalist predator–prey systems modeled in[E.Alexandra,F.Lutscher and G.Seo,Bistability and limit cycles in generalist predator–prey dynamics,Ecol.Complex.14(2013)48–55].When...This paper studies the dynamics of the generalist predator–prey systems modeled in[E.Alexandra,F.Lutscher and G.Seo,Bistability and limit cycles in generalist predator–prey dynamics,Ecol.Complex.14(2013)48–55].When prey reproduces much faster than predator,by combining the normal form theory of slow-fast systems,the geometric singular perturbation theory and the results near non-hyperbolic points developed by Krupa and Szmolyan[Relaxation oscillation and canard explosion,J.Differential Equations174(2)(2001)312–368;Extending geometric singular perturbation theory to nonhyperbolic points—fold and canard points in two dimensions,SIAM J.Math.Anal.33(2)(2001)286–314],we provide a detailed mathematical analysis to show the existence of homoclinic orbits,heteroclinic orbits and canard limit cycles and relaxation oscillations bifurcating from the singular homoclinic cycles.Moreover,on global stability of the unique positive equilibrium,we provide some new results.Numerical simulations are also carried out to support the theoretical results.展开更多
In this paper,we investigate the influence of the nonlocal prey competition on the spatiotemporal dynamics for a generalist predator-prey system.The condition of stability and bifurcations is clearly determined.Our re...In this paper,we investigate the influence of the nonlocal prey competition on the spatiotemporal dynamics for a generalist predator-prey system.The condition of stability and bifurcations is clearly determined.Our results show that when the prey spreads quickly,the nonlocal intraspecific competition of the prey does not affect the dynamics,however,when the prey spreads slowly,it can affect the dynamics.Besides,no Hopf bifurcation occurs if the ratio of the growth rate of the predator to prey is larger,otherwise,system has Hopf bifurcation and Hopf Bogdanov-Takens bifurcation and so on.It is surprised that the system only with the nonlocal prey competition has more rich dynamics than the system with the nonlocal competitions in both the prey and the predator.The coexistence of bistable spatially inhomogeneous steady states is also found.展开更多
文摘Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affecting prey choice. Two methods were used, an assessment of the extent to which an individual octopus made choices of species representative of those population （PSi and IS） and 25% cutoff values for number of choices and percentage intake of individual on their prey. In one population of Octopus cfvulgaris in Bermuda individuals were generalist by IS=0.77, but most chose many prey of the same species, and were specialists on it by 〉75% intake. Another population had a wider prey selection, still generalist with PSi=0.66, but two individuals specialized by choices. In Bonaire, there was a wide range of prey species chosen, and the population was specialists by IS=0.42. Individual choices revealed seven specialists and four generalists. A population of Octopus cyanea in Hawaii all had similar choices of crustaceans, so the population was generalist by IS with 0.74. But by individual choices, three were considered a spe-cialist. A population of Enteroctopus dofleini from Puget Sound had a wide range of preferences, in which seven were also spe-cialists, IS=0.53, By individual choices, thirteen were also specialists. Given the octopus specialty of learning during foraging, we hypothesize that both localized prey availability and individual personality differences could influence the exploration for prey and this translates into different prey choices across individuals and populations showed in this study.
基金supported by the National Natural Science Foundation of China(No.32030015,32470545)Science&Technology Fundamental Resources Investigation Program(Grant No.2022FY100400)+1 种基金the Key Projects of Science and Technology Research from the Education Department of Hubei Province(D20221002)the Project(No:RSP2025R7)of the King Saud University,Saudi Arabia.
文摘Micro-eukaryotic communities are highly sensitive to environmental changes, and their structure offers crucial insights into the impact of human activities on aquatic habitats. Despite their significance, the assembly mechanisms of micro-eukaryotic communities in lake ecosystems heavily influenced by human activities are not well understood. In this study, we utilized 18S rDNA amplicon sequencing to examine the biodiversity of micro-eukaryotes over a one-year period in Lake Weishan, one of the largest freshwater lakes in northern China. We analyzed the ecological processes governing community assembly among key ecological groups, specifically habitat generalists and specialists. Our findings revealed substantial temporal variation in microbial diversity and community composition, likely driven by water temperature, dissolved oxygen, and the concentrations of several ions (e.g., Ca^(2+) and F^(−)). Notably, community assembly in this canal-disturbed lake was predominantly influenced by stochastic processes (58.18%) rather than deterministic processes (20.46%). Habitat specialists (425 operational taxonomic units, OTUs) exhibited significantly greater diversity compared to habitat generalists (189 OTUs) and were predominantly shaped by stochastic processes (52.47%). In contrast, habitat generalists were less influenced by these processes (17.69%). Altogether, these results suggest that the ecological processes governing micro-eukaryotic community assembly differ markedly between habitat generalists and specialists, primarily due to their varied adaptability to environmental changes.
基金supported by NSF DEB-0613668,through collaborative grants NSF DEB-1120356 and 1119931(all to G.V.and R.C.K.B.)the DST/NRF Centre of Excellence at the FitzPatrick Institute,University of Cape Town(to R.C.K.B.).
文摘Avian species diversity in Southern Africa is remarkably high,yet the mechanisms responsible for that diversity are poorly understood.While this is particularly true with respect to species endemic to the subregion,it is unclear as to how more broadly distributed African species may have colonized southern Africa.One process that may in part account for the high bird species diversity in southern Africa is a“species pump”model,wherein the region was repeatedly colonized by lineages from areas further north:a pattern related to climate cycling and the eastern African arid corridor.Once occupying southern Africa,with its many varied biomes,it is possible that climate cycling further affected lineages by generating genetic diversity in multiple refugia,a pattern recently shown for several southern African bird species.Here,we used mtDNA to address these questions in a widespread,sedentary habitat generalist bird species,the familiar chat(Oenanthe familiaris).The phylogenetic structure suggests a northto-south colonization pattern,supporting the“species pump”model.Haplotype diversity was partitioned into two distinct clusters:southern Africa and Malawi(East Africa).Southern African haplotypes were not geographically partitioned,and we hypothesize that this pattern has arisen because this species is a habitat generalist,and as such resilient to habitat-altering climate perturbations.Based on our phylogenetic results,we discuss the validity of currently recognized subspecies.
基金This work was supported by a grant from the Swiss National Science Foundation to J.J.(nr.3100AO-104006).
文摘Aims The superior performance of many non-indigenous species in a new range can be attributed to different factors such as pre-adaptation to environmental conditions in new areas or to factors inherent to displacement mechanisms such as loss of co-evolved pathogens and herbivores that increase the speed of evolutionary change towards a shift in allocation from defence to growth and reproduction.To assess the importance of the different mechanisms governing the success of Conyza canadensis,a globally successful invader,we simultaneously tested several recent hypotheses potentially explaining the factors leading to biological invasion.Methods We tested(i)whether plants from the non-native range showed a higher fitness than plants from the native North American range,(ii)whether they differed in resistance against an invasive generalist herbivore,the slug Arion lusitanicus and against a recently established specialist aphid herbivore,Uroleucon erigeronense and(iii)experimentally assessed whether C.canadensis releases allelopathic chemicals that have harmful effects on competing species in the nonnative range.We compared populations along a similar latitudinal gradient both in the native North American and invasive European range and analysed patterns of adaptive clinal variation in biomass production.Important Findings The invasion success of C.canadensis in Europe cannot be attributed to a single trait,but to a combination of factors.Invasive plants benefited from increased growth and above all,increased reproduction(a key trait in an annual plant)and were less attacked by a co-migrated specialist enemy.The observed loss of defence against generalist slugs did not translate into a decreased fitness as invasive C.canadensis plants showed a high re-growth potential.In contrast to earlier in vitro studies,we detected no allelopathic effects on the competing flora in the non-native range.The latitudinal cline in vegetative biomass production in the non-native range observed in our common garden study indicates a high adaptive potential.However,only further genetic studies will provide conclusive evidence whether the differentiation in the non-native range is caused by pre-adaptation and sorting-out processes of putatively repeatedly introduced populations of this composite,long-distance disperser with highly volatile seeds or evolved de novo as a rapid response to new selection pressures in the nonnative range.
基金We would like to thank Xue-Fang Yang and Shun-Liang Feng for plant harvests. We also thank English editing by Van Driesche Scientific Editing. This work was sup- ported by the National Natural Science Foundation of China （31470447 and 31200286 to W. Huang, 31370404 to J. Ding）.
文摘Successful invasions by exotic plants are often attributed to a loss of co-evolved specialists and a re-allocation of resources from defense to growth and reproduction. However, invasive plants are rarely completely released from insect herbivory because they are frequently attacked by generalists in their introduced ranges. The novel generalist community may also affect the invasive plant＇s defensive strategies and resource allocation. Here, we tested this hypothesis using American pokeweed （Phytolacca americana L.）, a species that has become invasive in China, which is native to North America. We examined resistance, tolerance, growth and reproduction of plant populations from both China and the USA when plants were exposed to natural generalist herbivores in China. We found that leaf damage was greater for invasive populations than for native populations, indicating that plants from invasive ranges had lower resistance to herbivory than those from native ranges. A regression of the percentage of leaf damage against mass showed that there was no significant difference in tolerance between invasive and native populations, even though the shoot, root, fruit and total mass were larger for invasive populations than for native populations. These results suggest that generalist herbivores are important drivers mediating the defensive strategies and resource allocation of the invasive American pokeweed.
文摘Current evidence suggests that pollen is both chemically and structurally protected. Despite increasing interest in studying bee-flower networks, the constraints for bee development related to pollen nutritional content, toxicity and digestibility as well as their role in the shaping of bee-flower interactions have been poorly studied. In this study we combined bioassays of the generalist bee Bombus terrestris on pollen of Cirsium, Trifolium, Salix, and Cistus genera with an assessment of nutritional content, toxicity, and digestibility of pollen. Microcolonies showed significant differences in their development, non-host pollen of Cirsium being the most unfavorable. This pollen was characterized by the presence of quite rare 37-sterols and a low digestibility. Cirsium consumption seemed increase syrup collection, which is probably related to a detoxification mixing behavior. These results strongly suggest that pollen traits may act as drivers of plant selection by bees and partly explain why Asteraceae pollen is rare in bee generalist diet.
基金supported by Israel Science Foundation(grant 149/17 to ISK and BRK).
文摘We investigated the performance trade-offs of fleas(Siphonaptera)while adapting to a novel host using two host generalists(Xenopsylla conformis and Xenopsylla ramesis)and one host specialist(Parapulex chephrenis)maintained on their principal hosts(Meriones crassus for Xenopsylla and Acomys cahirinus for P.chephrenis).We asked whether,over generations,(i)a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and(ii)a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host.We established an experimental line of each species on a novel host(Acomys russatus for Xenopsylla and M.crassus for P.chephrenis)and maintained this line on this host during 23 generations.We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size,hatching success,offspring production,and offspring size.We found changes in performance over generations in female offspring size only.Xenopsylla conformis demonstrated a tendency to become a host specialist(increased performance on the novel host with a concomitant decreased performance on the original host),whereas P.chephrenis demonstrated a tendency to become a host generalist(increased performance on the novel host without a concomitant decreased performance on the original host).We conclude that the probability of generalist to specialist transition,and vice versa,is context-dependent and varies between species.
文摘This paper studies the dynamics of the generalist predator–prey systems modeled in[E.Alexandra,F.Lutscher and G.Seo,Bistability and limit cycles in generalist predator–prey dynamics,Ecol.Complex.14(2013)48–55].When prey reproduces much faster than predator,by combining the normal form theory of slow-fast systems,the geometric singular perturbation theory and the results near non-hyperbolic points developed by Krupa and Szmolyan[Relaxation oscillation and canard explosion,J.Differential Equations174(2)(2001)312–368;Extending geometric singular perturbation theory to nonhyperbolic points—fold and canard points in two dimensions,SIAM J.Math.Anal.33(2)(2001)286–314],we provide a detailed mathematical analysis to show the existence of homoclinic orbits,heteroclinic orbits and canard limit cycles and relaxation oscillations bifurcating from the singular homoclinic cycles.Moreover,on global stability of the unique positive equilibrium,we provide some new results.Numerical simulations are also carried out to support the theoretical results.
基金supported by grants from the National Natural Science Foundation of China(Nos.11971143 and 12071105)the Natural Science Foundation of Zhejiang Province(No.LZ23A010001).
文摘In this paper,we investigate the influence of the nonlocal prey competition on the spatiotemporal dynamics for a generalist predator-prey system.The condition of stability and bifurcations is clearly determined.Our results show that when the prey spreads quickly,the nonlocal intraspecific competition of the prey does not affect the dynamics,however,when the prey spreads slowly,it can affect the dynamics.Besides,no Hopf bifurcation occurs if the ratio of the growth rate of the predator to prey is larger,otherwise,system has Hopf bifurcation and Hopf Bogdanov-Takens bifurcation and so on.It is surprised that the system only with the nonlocal prey competition has more rich dynamics than the system with the nonlocal competitions in both the prey and the predator.The coexistence of bistable spatially inhomogeneous steady states is also found.
