BIOB50H3 Lecture Notes - Lecture 11: Intraspecific Competition
20 Oct 2015
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Document Summary
< species on earth obtain energy by feeding on other organisms: through exploitation. Population cycles can be caused by feeding relationships: a specific effect of exploitation can be population cycles. Limitations include dependency on initial numbers: predators rarely cause extinctions of prey in natural systems, habitat complexity. When prey are easy to find, predators typically drive them extinct, then themselves go extinct: example, huffaker (1958) and the mites on oranges. Increased complexity = better habitat for prey, poorer for predators: spatial refuges, prey switching, prey responding to predation, evolution. Hairston et al. discovered asynchronous population cycles. Why: predator egg viability increases with prey density, algal nutrition quality increases with [n, accumulation of toxins alters algal physiology, algae might evolve in response to predation. Yoshida et al (2003) tested all these in two ways. Use of single algal genotype to observe/test for evolution to different genotypes. When prey did not evolve, prey-pred cycles resulted. Br of hares drop during the decline.
