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Vesmír č. 10
Vesmír č. 10
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2. 10. 2017
Novinky
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Enemy-free space by Jan Šipoš, Tomáš Kuras and Monika Mazalová.

A distribution of particular individuals in nature is not governed by stochastic events. Proper taxon for studies of distribution of organisms is herbivorous insects. Many ecologists try to explain: i) spatial distribution; ii) temporal distribution; iii) specialization of herbivorous insects in an environment. A distribution of herbivores can be affected by vegetation which negatively influences fitness of herbivores thanks to low ratio of nitrogen to carbon and because of a content of toxic chemical substances. Predators can influence abundance of herbivores directly (killing the prey) or indirectly (stress factor). Interactions between herbivores, vegetation and predators can be changed by abiotic environmental factors. Environmental conditions can mitigate effect of predators and vegetation on herbivorous insect or can increase importance of one of these factors. From the perspective of the Enemy-free space theory the most important factor controlling distribution and abundance of insects is a predation. Herbivores can avoid predators by choosing a safe microhabitat or time period which is free from predators. Other possibility for herbivores is to specialize on particular plant and use its chemical defence against predators. Interaction between predators and its prey is not invariant but is very variable in time and space and we can describe it more like a mosaic. Therefore it is very difficult to proof if the enemy-free space exist.