Pub Date : 2010-01-14DOI: 10.2174/1874213001003020001
V. Rull
Despite what their names might suggest, ecology and palaeoecology have progressed historically as well separated disciplines. This unfortunate disjunction is analyzed here from a theoretical point of view. Among the factors that have facilitated the separation are: 1) the past-present dissociation characteristic of the human mind, 2) the diversity of fields of provenance of palaeoecologists, 3) the contrasting nature of the evidence and associated methodological differences, and 4) misunderstandings caused by the use of prefix palaeo-. The principle of uniformitarianism emphasizes that past, present and future are not discrete units but a time continuum through which species and communities flow, change and evolve; and that ecology and palaeoecology are only different approaches with a common objective, which is the ecological understanding of the biosphere. Therefore, a terminological clarification is needed. Ecology in a broad sense, includes inferences about the past (palaeoecology), present studies (neoecology or contemporary ecology) and future projections (predictive ecology). Palaeoecology is thus a means by which ecology studies the past using proxies. Other disciplines beginning with the prefix palaeo- (notably palaeoclimatology and palaeoenvironmental reconstruction) are not necessarily ecological. It is recommended that ecologists and palaeoecologists develop joint projects, and that palaeoecologists increase their participation in ecological journals, books and meetings. These collaborations will demonstrate that a palaeoecologist is not simply a palaeoscientist whose data may be of interest for ecology but is primarily an ecologist working on another time scale, with different methods.
{"title":"Ecology and Palaeoecology: Two Approaches, One Objective","authors":"V. Rull","doi":"10.2174/1874213001003020001","DOIUrl":"https://doi.org/10.2174/1874213001003020001","url":null,"abstract":"Despite what their names might suggest, ecology and palaeoecology have progressed historically as well separated disciplines. This unfortunate disjunction is analyzed here from a theoretical point of view. Among the factors that have facilitated the separation are: 1) the past-present dissociation characteristic of the human mind, 2) the diversity of fields of provenance of palaeoecologists, 3) the contrasting nature of the evidence and associated methodological differences, and 4) misunderstandings caused by the use of prefix palaeo-. The principle of uniformitarianism emphasizes that past, present and future are not discrete units but a time continuum through which species and communities flow, change and evolve; and that ecology and palaeoecology are only different approaches with a common objective, which is the ecological understanding of the biosphere. Therefore, a terminological clarification is needed. Ecology in a broad sense, includes inferences about the past (palaeoecology), present studies (neoecology or contemporary ecology) and future projections (predictive ecology). Palaeoecology is thus a means by which ecology studies the past using proxies. Other disciplines beginning with the prefix palaeo- (notably palaeoclimatology and palaeoenvironmental reconstruction) are not necessarily ecological. It is recommended that ecologists and palaeoecologists develop joint projects, and that palaeoecologists increase their participation in ecological journals, books and meetings. These collaborations will demonstrate that a palaeoecologist is not simply a palaeoscientist whose data may be of interest for ecology but is primarily an ecologist working on another time scale, with different methods.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"3 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2010-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68054922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-01-01DOI: 10.2174/1874213001003030031
W. Ripple, Luke E. Painter, R. Beschta, C. Gates
Wolves were reintroduced into Yellowstone National Park in 1995/96, likely reestablishing a trophic cascade involving wolves, elk, and woody browse species. The return of wolves may have also triggered a secondary trophic cascade involving bison, which are generally a minor prey species for wolves in northern Yellowstone. We hypothesize a sequence of events in northern Yellowstone where: 1) wolves prey on elk, changing elk behavior and reducing elk numbers, 2) causing reduced elk herbivory and more forage available to bison, and 3) allowing higher bison densities and additional bison effects on the ecosystem. This secondary trophic cascade, whereby wolf predation may have indirectly allowed bison numbers to increase through a reduction in inter-specific competition with elk, may represent an example of an alternative top-down pathway by which predators can influence multiple trophic levels through mediating the competitive interaction between two prey species. Both wolves and bison can have important effects on ecosystems, and there is growing interest in restoring these animals to wider portions of their former range. However, there are many potential routes for interactions between species and it is important to consider the conservation implications of other cascading effects when reintroducing such ecologically influential species into wild landscapes. The potential benefits of bison to their native ecosystems may not be realized in situations with low predation pressure, high bison densities, and constraints on bison movement and migration, thus likely contributing to impairment of resources.
{"title":"Wolves, Elk, Bison, and Secondary Trophic Cascades in Yellowstone National Park","authors":"W. Ripple, Luke E. Painter, R. Beschta, C. Gates","doi":"10.2174/1874213001003030031","DOIUrl":"https://doi.org/10.2174/1874213001003030031","url":null,"abstract":"Wolves were reintroduced into Yellowstone National Park in 1995/96, likely reestablishing a trophic cascade involving wolves, elk, and woody browse species. The return of wolves may have also triggered a secondary trophic cascade involving bison, which are generally a minor prey species for wolves in northern Yellowstone. We hypothesize a sequence of events in northern Yellowstone where: 1) wolves prey on elk, changing elk behavior and reducing elk numbers, 2) causing reduced elk herbivory and more forage available to bison, and 3) allowing higher bison densities and additional bison effects on the ecosystem. This secondary trophic cascade, whereby wolf predation may have indirectly allowed bison numbers to increase through a reduction in inter-specific competition with elk, may represent an example of an alternative top-down pathway by which predators can influence multiple trophic levels through mediating the competitive interaction between two prey species. Both wolves and bison can have important effects on ecosystems, and there is growing interest in restoring these animals to wider portions of their former range. However, there are many potential routes for interactions between species and it is important to consider the conservation implications of other cascading effects when reintroducing such ecologically influential species into wild landscapes. The potential benefits of bison to their native ecosystems may not be realized in situations with low predation pressure, high bison densities, and constraints on bison movement and migration, thus likely contributing to impairment of resources.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"3 1","pages":"31-37"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68055141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-12-15DOI: 10.2174/1874213000902010112
Debal Deb
Modern rice farms are characterized by the use of synthetic agrochemicals, which eliminate a large segment of biodiversity on-farm. In contrast, organic rice farms tend to preserve much of natural biodiversity. While biodiversity- productivity relationship in organic vs. chemicalised rice farms is contested, the relationship of on-farm biodiversity with food web structural properties and ecosystem services remains to be explored. To understand the functional significance of species richness and ecosystem complexity of rice farms, I examine here the architectural properties of rice food webs from West Bengal, based on replicated plots of folk variety (organic) and modern (chemicalised) rice systems. All rice food webs, constructed from observational data collected over three years, show prominent scale dependence of dietary links, link density, web height, diversity of natural enemies to pests, predator-pest ratio, and the numbers of omnivores and omnivory levels. Organic folk rice webs tend to have greater mean species richness, predator diversity, predator-pest ratio and chain length than modern rice farm webs, yet both systems show homogeneity of distribution of the web properties. Analyses of 16,400 computerized analog webs, following non-random rules of species association drawn on real-life, seasonally distinct rice food webs, validate the robustness of conclusions.
{"title":"Biodiversity and Complexity of Rice Farm Ecosystems: An Empirical Assessment","authors":"Debal Deb","doi":"10.2174/1874213000902010112","DOIUrl":"https://doi.org/10.2174/1874213000902010112","url":null,"abstract":"Modern rice farms are characterized by the use of synthetic agrochemicals, which eliminate a large segment of biodiversity on-farm. In contrast, organic rice farms tend to preserve much of natural biodiversity. While biodiversity- productivity relationship in organic vs. chemicalised rice farms is contested, the relationship of on-farm biodiversity with food web structural properties and ecosystem services remains to be explored. To understand the functional significance of species richness and ecosystem complexity of rice farms, I examine here the architectural properties of rice food webs from West Bengal, based on replicated plots of folk variety (organic) and modern (chemicalised) rice systems. All rice food webs, constructed from observational data collected over three years, show prominent scale dependence of dietary links, link density, web height, diversity of natural enemies to pests, predator-pest ratio, and the numbers of omnivores and omnivory levels. Organic folk rice webs tend to have greater mean species richness, predator diversity, predator-pest ratio and chain length than modern rice farm webs, yet both systems show homogeneity of distribution of the web properties. Analyses of 16,400 computerized analog webs, following non-random rules of species association drawn on real-life, seasonally distinct rice food webs, validate the robustness of conclusions.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"112-129"},"PeriodicalIF":0.0,"publicationDate":"2009-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68053854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-12-02DOI: 10.2174/1874213000902010091
Leslie Smith, J. D. Blue, J. Carlson, Grace Metz, J. Haywood, Daniel S. Bush, C. Paradise
The effects of predation on water-filled treehole communities in North Carolina were examined using mesocosm experiments and observations in natural treeholes. The presence of the predator Toxorhynchites rutilus and leaf litter abundance were manipulated in mesocosms to examine interactions between resources and predation. Long-term examination of interactions in unmanipulated treeholes provided data on natural variation in water volume and predator density. Toxorhynchites rutilus preys upon two common treehole insects, Aedes triseriatus and Culicoides guttipennis. We predicted that T. rutilus would act as a keystone predator and reduce the density of these dominant species. This would allow other species to coexist and lead to an increase in diversity. We also predicted that effects of predation would be reduced in habitats with high levels of resources, due to either increased refugia or decreased competition. The results did not entirely support the predictions. In both mesocosms and treeholes T. rutilus depressed densities of the most abundant prey type, A. triseriatus. In treeholes, the presence of T. rutilus depressed densities of the midge C. guttipennis, and predator densities were positively associated with insect diversity in treeholes. Strikingly, higher diversity was also associated with high densities of the dominant prey in treeholes. In addition, mesocosms showed no relationship between T. rutilus presence and species diversity. The relationship between the predator and diversity in treeholes appears to be unrelated to predation on the dominant competitors and is instead caused by some other habitat characteristic. While there were effects of resources on densities and diversity in both mesocosms and treeholes, neither of the resources analyzed, leaf litter or water, appear to be the sole characteristic that mutually allows for large populations of T. rutilus and high species diversity. We conclude that though T. rutilus is an aggressive predator, it does not cause an increase in prey species diversity as a keystone predator would. Further research is needed to determine the conditions that favor the presence of predator and high prey diversity.
{"title":"Density-Dependent Predation of a Dominant Species does not Facilitate Increased Diversity in Treeholes","authors":"Leslie Smith, J. D. Blue, J. Carlson, Grace Metz, J. Haywood, Daniel S. Bush, C. Paradise","doi":"10.2174/1874213000902010091","DOIUrl":"https://doi.org/10.2174/1874213000902010091","url":null,"abstract":"The effects of predation on water-filled treehole communities in North Carolina were examined using mesocosm experiments and observations in natural treeholes. The presence of the predator Toxorhynchites rutilus and leaf litter abundance were manipulated in mesocosms to examine interactions between resources and predation. Long-term examination of interactions in unmanipulated treeholes provided data on natural variation in water volume and predator density. Toxorhynchites rutilus preys upon two common treehole insects, Aedes triseriatus and Culicoides guttipennis. We predicted that T. rutilus would act as a keystone predator and reduce the density of these dominant species. This would allow other species to coexist and lead to an increase in diversity. We also predicted that effects of predation would be reduced in habitats with high levels of resources, due to either increased refugia or decreased competition. The results did not entirely support the predictions. In both mesocosms and treeholes T. rutilus depressed densities of the most abundant prey type, A. triseriatus. In treeholes, the presence of T. rutilus depressed densities of the midge C. guttipennis, and predator densities were positively associated with insect diversity in treeholes. Strikingly, higher diversity was also associated with high densities of the dominant prey in treeholes. In addition, mesocosms showed no relationship between T. rutilus presence and species diversity. The relationship between the predator and diversity in treeholes appears to be unrelated to predation on the dominant competitors and is instead caused by some other habitat characteristic. While there were effects of resources on densities and diversity in both mesocosms and treeholes, neither of the resources analyzed, leaf litter or water, appear to be the sole characteristic that mutually allows for large populations of T. rutilus and high species diversity. We conclude that though T. rutilus is an aggressive predator, it does not cause an increase in prey species diversity as a keystone predator would. Further research is needed to determine the conditions that favor the presence of predator and high prey diversity.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"91-99"},"PeriodicalIF":0.0,"publicationDate":"2009-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68054143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-12-02DOI: 10.2174/1874213000902010100
P. Crowley, Y. Saeki
The trade-off between the number of offspring in a brood and the sizes of those offspring has been documented in a diverse array of species. Here we consider the factors that might account for the way that the trade-off achieves a particular size-number balance for female offspring. In particular, we determine whether bet hedging, along with traits influencing the expected short-term reproductive success of the brood, could select for a brood size and body mass that maximize long-term fitness. We also evaluate whether the optima based on these characteristics agree qualitatively with documented responses to brood resource levels. To develop a model incorporating these phenomena and keep it as simple and general as possible, we consider an organism that produces clonal broods, eliminating the complexities associated with parent-offspring and sibling conflict. We use the polyembryonic parasitoid wasp Copidosoma bakeri as the focal example. We find that bet hedging effects and key reproductive traits (the number of searching females, their host-finding efficiency, and survival prospects) are often sufficient to produce an optimal size-number balance and can account for the frequent tendency of both brood size and body mass to increase with brood resources (host size). Under some conditions, however, balancing the trade-off requires an additional minimum body-size constraint. Future empirical work and spatially explicit models must better establish the parameter magnitudes and functional relationships so that a deeper understanding and more precise predictions are obtained.
{"title":"Balancing the Size-Number Tradeoff in Clonal Broods","authors":"P. Crowley, Y. Saeki","doi":"10.2174/1874213000902010100","DOIUrl":"https://doi.org/10.2174/1874213000902010100","url":null,"abstract":"The trade-off between the number of offspring in a brood and the sizes of those offspring has been documented in a diverse array of species. Here we consider the factors that might account for the way that the trade-off achieves a particular size-number balance for female offspring. In particular, we determine whether bet hedging, along with traits influencing the expected short-term reproductive success of the brood, could select for a brood size and body mass that maximize long-term fitness. We also evaluate whether the optima based on these characteristics agree qualitatively with documented responses to brood resource levels. To develop a model incorporating these phenomena and keep it as simple and general as possible, we consider an organism that produces clonal broods, eliminating the complexities associated with parent-offspring and sibling conflict. We use the polyembryonic parasitoid wasp Copidosoma bakeri as the focal example. We find that bet hedging effects and key reproductive traits (the number of searching females, their host-finding efficiency, and survival prospects) are often sufficient to produce an optimal size-number balance and can account for the frequent tendency of both brood size and body mass to increase with brood resources (host size). Under some conditions, however, balancing the trade-off requires an additional minimum body-size constraint. Future empirical work and spatially explicit models must better establish the parameter magnitudes and functional relationships so that a deeper understanding and more precise predictions are obtained.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"100-111"},"PeriodicalIF":0.0,"publicationDate":"2009-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68053660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-10-21DOI: 10.2174/1874213000902010086
R. Thomas Palo, Gert E. Olsson
We found that concentrations of nitrogen (N) in the stomach of voles varied between forest sites. Concentrations of nitrogen as well as the ratio of nitrogen to carbon (C) in stomach content were not different between the sexes or with season. Body mass varied between sites and between seasons but were unrelated to N concentration in spite that the body mass of voles in the spring season were on average 4.8 g heavier than in the autumn A positive relationship was found between N and C concentrations in the stomach content implying the diet quality could be related to this ratio. N concentrations in the stomach per unit body mass were positively and significantly related to catch per unit effort of voles. We suggest that sites with high N concentrations in stomach content and with higher NC-ratio imply better habitats that support higher population densities of voles.
{"title":"Nitrogen and Carbon Concentrations in the Stomach Content of Bank Voles (Myodes glareolus). Does Food Quality Determine Abundance","authors":"R. Thomas Palo, Gert E. Olsson","doi":"10.2174/1874213000902010086","DOIUrl":"https://doi.org/10.2174/1874213000902010086","url":null,"abstract":"We found that concentrations of nitrogen (N) in the stomach of voles varied between forest sites. Concentrations of nitrogen as well as the ratio of nitrogen to carbon (C) in stomach content were not different between the sexes or with season. Body mass varied between sites and between seasons but were unrelated to N concentration in spite that the body mass of voles in the spring season were on average 4.8 g heavier than in the autumn A positive relationship was found between N and C concentrations in the stomach content implying the diet quality could be related to this ratio. N concentrations in the stomach per unit body mass were positively and significantly related to catch per unit effort of voles. We suggest that sites with high N concentrations in stomach content and with higher NC-ratio imply better habitats that support higher population densities of voles.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"86-90"},"PeriodicalIF":0.0,"publicationDate":"2009-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68054100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-10-13DOI: 10.2174/1874213000902010083
P. Munguia, A. Ojanguren, A. Evans, L. Ryckman, B. Gemmell, Colt Cook, G. Hensgen
Current ecological literature considers facilitation to be a positive interaction alongside symbiosis or mutualism. But unlike these interactions, the fitness of one of the species involved in facilitation remains unaffected which precludes coevolution. Therefore, we believe that facilitation is not a true species interaction and should be kept within the framework of succession.
{"title":"Is Facilitation a True Species Interaction","authors":"P. Munguia, A. Ojanguren, A. Evans, L. Ryckman, B. Gemmell, Colt Cook, G. Hensgen","doi":"10.2174/1874213000902010083","DOIUrl":"https://doi.org/10.2174/1874213000902010083","url":null,"abstract":"Current ecological literature considers facilitation to be a positive interaction alongside symbiosis or mutualism. But unlike these interactions, the fitness of one of the species involved in facilitation remains unaffected which precludes coevolution. Therefore, we believe that facilitation is not a true species interaction and should be kept within the framework of succession.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"83-85"},"PeriodicalIF":0.0,"publicationDate":"2009-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68054086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-08-25DOI: 10.2174/1874213000902010074
L. Hein
Pollination is an ecosystem service that is essential to support the production of a wide range of crops. The service is increasingly under threat, as a consequence of among others habitat loss of pollinators and increasing use of pesticides. In order to support maintaining the pollination service in agriculture, there is a need to better understand the economic value generated by the pollination service. This paper discusses the appropriate valuation methods for pollination at different scales, and presents an analysis of the value of the pollination service based on a literature review. At the local scale, the value of the service is highly variable depending on the crop and the market conditions. At the national scale, value estimates of the pollination service range from 1% to 16% of the market value of agricultural production. At the global scale, there is currently no reliable estimate of the value of this service. When the economic value of the pollination service is analysed, it is critical to adjust the valuation approach to the scale of the analysis.
{"title":"The Economic Value of the Pollination Service, a Review Across Scales","authors":"L. Hein","doi":"10.2174/1874213000902010074","DOIUrl":"https://doi.org/10.2174/1874213000902010074","url":null,"abstract":"Pollination is an ecosystem service that is essential to support the production of a wide range of crops. The service is increasingly under threat, as a consequence of among others habitat loss of pollinators and increasing use of pesticides. In order to support maintaining the pollination service in agriculture, there is a need to better understand the economic value generated by the pollination service. This paper discusses the appropriate valuation methods for pollination at different scales, and presents an analysis of the value of the pollination service based on a literature review. At the local scale, the value of the service is highly variable depending on the crop and the market conditions. At the national scale, value estimates of the pollination service range from 1% to 16% of the market value of agricultural production. At the global scale, there is currently no reliable estimate of the value of this service. When the economic value of the pollination service is analysed, it is critical to adjust the valuation approach to the scale of the analysis.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"74-82"},"PeriodicalIF":0.0,"publicationDate":"2009-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68054020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-07-29DOI: 10.2174/1874213000902010047
S. Renner
I captured birds in a central Guatemalan cloud forest (Sierra Yalijux) in two adjacent habitats, with different habitat structure to assess the influence of land use on bird populations. The regional population of Common Bush- Tanager (Chlorospingus ophthalmicus) showed a pattern of spatial separation of 1 st -year individuals vs. adults, a pattern not shown so far for any bird species. During the early post-breeding season, I captured similar numbers of adult individuals in both natural and young secondary forest (38 vs. 43), while 1 st -year individuals were captured mainly in young secondary vegetation (3 vs. 40). The findings indicate that inexperienced, young or less competitive individuals may use other habitats than adults, at least temporarily.
{"title":"Spatial Post-Breeding Segregation of 1st-Year and Adult Common Bush-Tanagers in a Guatemalan Cloud Forest","authors":"S. Renner","doi":"10.2174/1874213000902010047","DOIUrl":"https://doi.org/10.2174/1874213000902010047","url":null,"abstract":"I captured birds in a central Guatemalan cloud forest (Sierra Yalijux) in two adjacent habitats, with different habitat structure to assess the influence of land use on bird populations. The regional population of Common Bush- Tanager (Chlorospingus ophthalmicus) showed a pattern of spatial separation of 1 st -year individuals vs. adults, a pattern not shown so far for any bird species. During the early post-breeding season, I captured similar numbers of adult individuals in both natural and young secondary forest (38 vs. 43), while 1 st -year individuals were captured mainly in young secondary vegetation (3 vs. 40). The findings indicate that inexperienced, young or less competitive individuals may use other habitats than adults, at least temporarily.","PeriodicalId":39335,"journal":{"name":"Open Ecology Journal","volume":"2 1","pages":"47-51"},"PeriodicalIF":0.0,"publicationDate":"2009-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68053943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-07-29DOI: 10.2174/1874213000902010062
D. Jackson, J. Vandermeer, I. Perfecto
Recent studies have shown that the spatial pattern of nests of an arboreal ant, Azteca instabilis (Hymenoptera: Formicidae), in a tropical coffee agroecosystem may emerge through self-organization. The proposed self-organization process involves both local expansion and density-dependent mortality of the ant colonies. We explored a possible mechanism for the density-dependent mortality involving the entomopathogenic fungus Lecanicillium lecanii. L. lecanii attacks a scale insect, Coccus viridis (Coccidae, Hemiptera), which is tended by A. instabilis in a mutualistic association. By attacking C. viridis, L. lecanii may have an indirect, negative effect on ant colony survival. To explore this hypothesis, we conducted investigations into the spatial and temporal distributions of L. lecanii. We measured incidence and severity at 4 spatial scales: (1) throughout a 45 hectare study plot; (2) in two 40 X 50 meter plots; (3) on coffee bushes within 4 m of two ant nests; and (3) on individual branches in a single coffee bush. The plot-level censuses did not reveal a clear spatial pattern, but the finer scale surveys show distinct patterns in the spread of infection over time. We also developed a simple cellular automata model of the coupled ant nest-L. lecanii system which is able to produce spatial patterns qualitatively and quantitatively similar to that found in the field. The accumulated evidence suggests that L. lecanii may very well be responsible for the density-dependent control thought necessary for spatial pattern formation of ant nests in this system.
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