نتایج جستجو برای: trophic levels

تعداد نتایج: 930571  

Journal: :Marine Ecology Progress Series 1985

In the present study, a trophic structure model for some fish species of the northern Oman Sea is developed through using mass balance modeling software, Ecopath with Ecosim (EwE). In this model, we simulated 16 functional groups spread across an area of 3998.20 km2 from 2017 to 2018. Mean trophic level in the area of the present study was 3.49. Values calculated for system omnivory and connect...

Journal: :Revista de biologia tropical 2011
Camilo B García Cristian Camilo Contreras

Ecological studies on commercial important fish species are of great value to support resource management issues. This study calculated trophic levels of those Colombian Caribbean fish species whose diet has been locally described. Usable diet data of 119 species resulted in 164 trophic level estimates. An ordinary regression model relating trophic level and fish size was formulated. The regres...

Journal: :The American naturalist 2008
D S Srivastava M K Trzcinski B A Richardson B Gilbert

Ecologists have hypothesized that the exponent of species-area power functions (z value) should increase with trophic level. The main explanation for this pattern has been that specialist predators require prior colonization of a patch by their prey, resulting in a compounding of the effects of area up trophic levels. We propose two novel explanations, neither of which assumes trophic coupling ...

Journal: :Proceedings. Biological sciences 2010
K H Andersen M Pedersen

The largest perturbation on upper trophic levels of many marine ecosystems stems from fishing. The reaction of the ecosystem goes beyond the trophic levels directly targeted by the fishery. This reaction has been described either as a change in slope of the overall size spectrum or as a trophic cascade triggered by the removal of top predators. Here we use a novel size- and trait-based model to...

Journal: :The Journal of animal ecology 2015
Guadalupe Peralta Carol M Frost Raphael K Didham Arvind Varsani Jason M Tylianakis

Incorporating the evolutionary history of species into community ecology enhances understanding of community composition, ecosystem functioning and responses to environmental changes. Phylogenetic history might partly explain the impact of fragmentation and land-use change on assemblages of interacting organisms and even determine potential cascading effects across trophic levels. However, it r...

2004
Saskya van Nouhuys

Species experience landscapes differently depending on their needs and behaviors, and on their trophic level. We expect species at high trophic levels in a community to be more sensitive to habitat fragmentation than species at lower trophic levels. But this depends on attributes such as resource breadth, dispersiveness, reproductive rate, and longevity, which may not be related to trophic leve...

Journal: :Science 2009
Andrew A Forbes Thomas H Q Powell Lukasz L Stelinski James J Smith Jeffrey L Feder

A major cause for biodiversity may be biodiversity itself. As new species form, they may create new niches for others to exploit, potentially catalyzing a chain reaction of speciation events across trophic levels. We tested for such sequential radiation in the Rhagoletis pomonella (Diptera: Tephritidae) complex, a model for sympatric speciation via host plant shifting. We report that the parasi...

Journal: :Ecology 2007
Ross M Thompson Martin Hemberg Brian M Starzomski Jonathan B Shurin

The concept of trophic levels is one of the oldest in ecology and informs our understanding of energy flow and top-down control within food webs, but it has been criticized for ignoring omnivory. We tested whether trophic levels were apparent in 58 real food webs in four habitat types by examining patterns of trophic position. A large proportion of taxa (64.4%) occupied integer trophic position...

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