Ecology Final Exam Notes (Coloured)

Forbidden combination yield differences in

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forbidden combination yield differences in distribution in geographical space - Gilpin et al. (1986) found experimental support for assembly rules: - Prediction: Remaining species will be randomly drawn from starting pool of 10 Drosophila species. - But between 2 and 7 species combinations consistently appear in the experiment (there is competitive exclusion, and there are assembly rules). Real world: - Similarly, Gotelli and Graves (1993) found that congeneric bird species rarely coexist in the same rainforest habitats. - This supports the existence of assembly rules affecting species composition in a biotic community Lecture 13 Trophic interactions
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- Herbivory and its impacts - Do predators control prey populations? - How do prey populations persist despite predation? - Notice how the lynxes’ pattern closely follows the hares’ pattern, but that the lynxes’ peaks and valleys happen a bit after the hares’ peaks and valleys. Why do you think the lynx population so closely follows the hare population? - The lynx and hare populations have a predator-prey relationship. - Without flux, vegetation wouldn’t have a chance to recover from the hare population’s continuous eating, and without vegetation, the hare population could no longer exist in its habitat, and therefore neither could the lynx population that depends upon the hare population for food. - Every ten years, hares’ reproduction rate increases, more hares born and eating up their food supply - Eat so much that they are forced to supplement food with less nutritious food - Hare population grows, so does lynx population - Hares get hunted and die from illness and disease because of lack of food source, hare population goes into decline - Lynx population also declines, some lynxes starve and die due to disease - Both populations decrease giving time for vegetation to recover, once there is enough vegetation then hare populations increase again, same with lynxes and cycle restarts - Herbivory (consumption of plants) strongly affects plant communities - Herbivory by introduced species can cause serious habitat destruction ex. Introduced goats and Hawaiian honeycreepers - Herbivory can be sufficiently extensive to have global change consequences - What controls the global diversity of herbivores?
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Factors that control the global diversity of herbivore: - Amount of moisture and nutrients that herbivores derive from consuming plants. - Herbivore diversity can be related to the nature of the local plant quality - Plant quality in terms of water and nutrients control the sufficient amount of water and nutrients for herbivores to persist. - In areas where plants have a lot of nutrients you have areas with a lot of herbivore density and vice versa. - Linear relation is presented between nutrients availability and herbivore diversity.
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