Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines.Although studies exploring the dynamics and competitio...Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines.Although studies exploring the dynamics and competition between tigers(Panthera tigris)and leopards(P.pardus)span decades,there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale,as well as the drivers determining their exploitative and interference competition.We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models;we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards.Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms.Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche.In addition,they showed a higher dietary overlap in the prey-rich regions.We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures.Meanwhile,studies with multiple metrics would promote the detection of interference competition.Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale.Policy-makers and managers should pay more attention to the factors of elevation,prey abundance,and habitat structures for the conservation of tigers and leopards.展开更多
There is accumulating evidence that sexual interactions among species （reproductive interference） could have dramatic effects for species＇ coexistence. It has been shown that the fitness of individuals can be subst...There is accumulating evidence that sexual interactions among species （reproductive interference） could have dramatic effects for species＇ coexistence. It has been shown that the fitness of individuals can be substantially reduced as a consequence of reproductive interference. This might subsequently lead to displacement of a species （sexual exclusion）. On the other hand, some evolutionary and ecological mechanisms might enable species to coexist, such as the divergence of mate recognition systems （reproductive character displacement）, habitat partitioning, clumped dispersion patterns or different colonization capabilities. We have previously shown that the two ground-hopper species Tetrix subulata and Tetrix ceperoi interact sexually in the laboratory as well as in the field. At sites where both species co-occur niche overlap was high, suggesting that coexistence is maintained by different niche breadths rather than by habitat partitioning. To test the hypothesis that habitat partitioning does not contribute to species＇ coexistence, we examined whether allotopic and syntopic populations of these two species differ in niche overlap （competitive release）, Our results show that niche overlap is higher in syntopic than in allotopic populations, suggesting that the site-specific habitat structure （heterogeneity） has a stronger influence on microhabitat utilization than the presence of heterospecifics. Hence, our data do not support the hypothesis that habitat partitioning plays a substantial role for the coexistence of these sexually interacting species.展开更多
In this paper, the existence of coexistence states in the Voterra Lotka competition model under Dirichlet boundary conditions is the major concern. Attention will be focused on the logistic equation. With a comparison...In this paper, the existence of coexistence states in the Voterra Lotka competition model under Dirichlet boundary conditions is the major concern. Attention will be focused on the logistic equation. With a comparison theorem an inequality satisfied by the solution of logistic equation is established. Some improved sufficient conditions for the existence of coexistence states are obtained.展开更多
Aims Lianas are expected to influence composition,structure and func-tioning of forest systems due to unequal distribution across the potential set of host plants.However,our understanding of mecha-nisms associated wi...Aims Lianas are expected to influence composition,structure and func-tioning of forest systems due to unequal distribution across the potential set of host plants.However,our understanding of mecha-nisms associated with preferences for specific hosts is still limited,and so is our ability to discern between endogenous and exogenous forces driving forest dynamics in the long run.In this paper,we eval-uated whether the dominant liana Hedera helix can indirectly con-tribute to the eventual dominance of the small multi-stemmed tree Corylus avellana in a remnant temperate forest in central Iberian Peninsula from comparatively reduced liana infestation on C.avel-lana relative to co-occurring woody species.Methods through principal component analysis and co-occurrence ana-lysis,we studied the distribution and spatial association between woody species and the liana H.helix.We analyzed the relationship between the number of species in a plot and the number of species infested by the liana to test the hypothesis that H.helix is a gen-eralist liana.through generalized linear mixed models,we tested the dynamic-multi-stemmed growth form of C.avellana as a plaus-ible life strategy to withstand,in the long run,the liana infestation.In particular,we tested(i)the relationship between stem size and the probability of H.helix infestation including all the tree species within plots and(ii)the relationship between stem size and mortal-ity as evidence of the stem turn over in the tree C.avellana.Important Findings Our results indicate that H.helix and C.avellana significantly co-occur in mature stands of this remnant temperate forest where pion-eer woody species are absent.Hedera helix severely infests all the woody species whenever stem size exceed≈25 cm perimeter and there is physical contact at the base of the stem.this implies that all the trees in the community are potential hosts for H.helix.Mixed models indicate that both,infestation by H.helix and stem mortality,are positively related to C.avellana stem perimeter.Reduced lon展开更多
It has been suggested that spatial heterogeneity is key to the coexistence at local spatial scales of subordinate and dominant predator species by allowing the former to shift to more protective habitats when the risk...It has been suggested that spatial heterogeneity is key to the coexistence at local spatial scales of subordinate and dominant predator species by allowing the former to shift to more protective habitats when the risk of intraguild predation exists. Here, we show how the smaller carnivore Egyptian mongoose (Herpestes ichneumon) may coexist on a local scale with its intraguild pre- dator, the Iberian lynx (Lynx pardinus), by using places with different microhabitat character- istics. We expect that mongooses living within lynx home ranges will use denser and more protective habitats when active in order to di- minish their risk of being killed by lynx com- pared to those living in areas similar in vege- tation and prey availability but where lynx are absent. The scrubland cover of points used by mongooses outside lynx areas, and that of points located within lynx areas but not used by mongooses, were significantly lower than, or similar to, cover of points used by mongooses within lynx areas. The probability of finding mon- goose tracks was constant across levels of scrubland cover when lynx were absent, but more mongoose tracks were likely to be found in thicker scrubland within lynx areas, especially if these areas were intensively used by lynx. This result agrees with the hypothesis on shifts in microhabitat use of subordinate carnivores to prevent fatal or risky encounters with dominant ones.展开更多
基金supported by grants from the National Natural Science Foundation of China(31971539)the National Science and Technology Basic Resources Survey Program of China(2019FY101700 and 2021FY100702)the Research Project of Tianjin Normal University(52XB2010).
文摘Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines.Although studies exploring the dynamics and competition between tigers(Panthera tigris)and leopards(P.pardus)span decades,there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale,as well as the drivers determining their exploitative and interference competition.We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models;we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards.Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms.Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche.In addition,they showed a higher dietary overlap in the prey-rich regions.We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures.Meanwhile,studies with multiple metrics would promote the detection of interference competition.Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale.Policy-makers and managers should pay more attention to the factors of elevation,prey abundance,and habitat structures for the conservation of tigers and leopards.
文摘There is accumulating evidence that sexual interactions among species （reproductive interference） could have dramatic effects for species＇ coexistence. It has been shown that the fitness of individuals can be substantially reduced as a consequence of reproductive interference. This might subsequently lead to displacement of a species （sexual exclusion）. On the other hand, some evolutionary and ecological mechanisms might enable species to coexist, such as the divergence of mate recognition systems （reproductive character displacement）, habitat partitioning, clumped dispersion patterns or different colonization capabilities. We have previously shown that the two ground-hopper species Tetrix subulata and Tetrix ceperoi interact sexually in the laboratory as well as in the field. At sites where both species co-occur niche overlap was high, suggesting that coexistence is maintained by different niche breadths rather than by habitat partitioning. To test the hypothesis that habitat partitioning does not contribute to species＇ coexistence, we examined whether allotopic and syntopic populations of these two species differ in niche overlap （competitive release）, Our results show that niche overlap is higher in syntopic than in allotopic populations, suggesting that the site-specific habitat structure （heterogeneity） has a stronger influence on microhabitat utilization than the presence of heterospecifics. Hence, our data do not support the hypothesis that habitat partitioning plays a substantial role for the coexistence of these sexually interacting species.
文摘In this paper, the existence of coexistence states in the Voterra Lotka competition model under Dirichlet boundary conditions is the major concern. Attention will be focused on the logistic equation. With a comparison theorem an inequality satisfied by the solution of logistic equation is established. Some improved sufficient conditions for the existence of coexistence states are obtained.
基金J.M.G.was granted with a Postdoctoral Fellowship at the University of Alcalá.E.G.thanks support of FONDECYT grant 1140070The last sampling period was funded by the FUNDIVER project(MINECO:CGL2015-69186-C2-2-R).
文摘Aims Lianas are expected to influence composition,structure and func-tioning of forest systems due to unequal distribution across the potential set of host plants.However,our understanding of mecha-nisms associated with preferences for specific hosts is still limited,and so is our ability to discern between endogenous and exogenous forces driving forest dynamics in the long run.In this paper,we eval-uated whether the dominant liana Hedera helix can indirectly con-tribute to the eventual dominance of the small multi-stemmed tree Corylus avellana in a remnant temperate forest in central Iberian Peninsula from comparatively reduced liana infestation on C.avel-lana relative to co-occurring woody species.Methods through principal component analysis and co-occurrence ana-lysis,we studied the distribution and spatial association between woody species and the liana H.helix.We analyzed the relationship between the number of species in a plot and the number of species infested by the liana to test the hypothesis that H.helix is a gen-eralist liana.through generalized linear mixed models,we tested the dynamic-multi-stemmed growth form of C.avellana as a plaus-ible life strategy to withstand,in the long run,the liana infestation.In particular,we tested(i)the relationship between stem size and the probability of H.helix infestation including all the tree species within plots and(ii)the relationship between stem size and mortal-ity as evidence of the stem turn over in the tree C.avellana.Important Findings Our results indicate that H.helix and C.avellana significantly co-occur in mature stands of this remnant temperate forest where pion-eer woody species are absent.Hedera helix severely infests all the woody species whenever stem size exceed≈25 cm perimeter and there is physical contact at the base of the stem.this implies that all the trees in the community are potential hosts for H.helix.Mixed models indicate that both,infestation by H.helix and stem mortality,are positively related to C.avellana stem perimeter.Reduced lon
基金funded by project CGL2004-00346/BOS of Ministry of Education and Sciencesupported by a predoctoral grant of CSIC-Spanish Council for Research,“I3P”programsupported by a FPU and a post-doctoral fellowships from the Spanish Ministry of Education.
文摘It has been suggested that spatial heterogeneity is key to the coexistence at local spatial scales of subordinate and dominant predator species by allowing the former to shift to more protective habitats when the risk of intraguild predation exists. Here, we show how the smaller carnivore Egyptian mongoose (Herpestes ichneumon) may coexist on a local scale with its intraguild pre- dator, the Iberian lynx (Lynx pardinus), by using places with different microhabitat character- istics. We expect that mongooses living within lynx home ranges will use denser and more protective habitats when active in order to di- minish their risk of being killed by lynx com- pared to those living in areas similar in vege- tation and prey availability but where lynx are absent. The scrubland cover of points used by mongooses outside lynx areas, and that of points located within lynx areas but not used by mongooses, were significantly lower than, or similar to, cover of points used by mongooses within lynx areas. The probability of finding mon- goose tracks was constant across levels of scrubland cover when lynx were absent, but more mongoose tracks were likely to be found in thicker scrubland within lynx areas, especially if these areas were intensively used by lynx. This result agrees with the hypothesis on shifts in microhabitat use of subordinate carnivores to prevent fatal or risky encounters with dominant ones.
