Chapter 53 Notes

Chapter 53 Notes - Chapter 53 Notes Community Ecology...

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Chapter 53 Notes Community Ecology Community: interacting species, usually living within a defined area 53.1 Species Interactions The species in a community interact almost constantly Fitness: the ability to survive and produce offsprings Competition: when individuals use the same resources – resulting in lower fitness for both (-/-) Consumption: when one organism eats or absorbs nutrients from another – the interaction increases the consumer’s fitness but decreases the victim’s fitness (+/-) Mutualism: when two species interact in a way that confers fitness benefits to both (+/ +) bees and flowers Commensalism: when one species benefits but the other species is unaffected (+/0) Three Themes ***As you analyze each type of species interaction, watch for three key themes o Species interaction can affect the distribution and abundance of a particular species Yucca plant/yucca moth + hare and lynx Species act as agents of natural selection when they interact o Ex: deer w/ wolves and cougars o Coevolution: a pattern of evolution in which two interacting species reciprocally influence each other’s adaptations over time o Coevolutionary arms race: a repeating cycle of reciprocal adaptation In humans: weapons and technology In biology: predators and prey, parasites and hosts, and other types of interacting species The outcome of interactions among species is dynamic and conditional o Ex: army ants and birds Competition Intraspecific competition: “within species” competition that occurs between members of the same species Interspecific competition: “between species” occurs when individuals from different species use the same limiting resources Using the niche concept to analyze interspecific competition Niche: the range of resources that the species is able to use or the range of conditions it can tolerate Interspecific competition occurs when the niches of two species overlap What happens when one species is a better competitor? G. F. Gause claimed it is not possible for species with the same niche to coexist o Competitive exclusion principal ^^^ Asymmetric competition: one species suffers a much greater fitness decline than the other species does
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Symmetric competition: each of the interacting species experiences a roughly equal decrease in fitness A species’ fundamental niche is the combination of resources or areas used or conditions tolerated in the absence of competitors A species’ realized niche is the portion of resources or areas used or conditions tolerated when competition occurs Experimental studies of competition This is a common experimental strategy in competition studies: one of the competitors is removed, and the response by the remaining species is observed Fitness trade-offs in competition Fitness trade-offs: inevitable compromises in adaptation If individuals are extremely good at competing for a particular resource, then they are
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This note was uploaded on 02/12/2012 for the course SCI 2341 taught by Professor Yates during the Spring '11 term at Alabama.

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Chapter 53 Notes - Chapter 53 Notes Community Ecology...

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