Community Interactions Learning Objectives - General Biology | BIOL 1001, Study notes of Biology

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Chapter Learning Objectives Chapter 27: Community Interactions 27.1 Why are community interactions important?  Define ecological community o All the interacting populations within an ecosystem o The biotic, or living, component of an ecosystem  List the categories of interspecific interactions and explain how each interaction may affect the population densities of the two species involved o Competition- harms A and B o Predation by A on B- benefits A, harms B o Parasitism by A on B- benefits A, harms B o Mutualism between A and B- benefits A and B 27.2 What is the relationship between ecological niche and competition?  Explain the competitive exclusion principle and describe the experiment that illustrates this principle o If 2 species occupy the same niche, one will win and the other will die out o One paramecium competitively excludes another species of paramecium  Define an ecological niche o Role of a particular species within an ecosystem; interactions with biotic and abiotic components  Define resource partitioning and explain how interspecific competition may lead to resource partitioning o When species with similar ecological niches coexist and compete, each species occupies a smaller niche than it would by itself o Competing species evolve physical and behavioral adaptations that reduce their competitive interactions  Explain how competition may reduce population sizes and distribution of the species involved o Although natural selection leads to a reduction of niche overlap between different species, those with similar niches still compete of limited resources, causing both populations to be restricted 27.3 What are the results of interactions between predators and their prey?  Explain the roles of predators and prey in a community o Predators eat other organisms (prey)  Give specific examples of adaptations of predators and prey o Camouflage- coloration and/or shape that renders an organism inconspicuous in its environment o Warning coloration- bright coloration that warns predators that the potential prey is distasteful, poisonous, or otherwise dangerous o Warning mimicry- some animals gain protection by resembling other dangerous animals that display warning coloration o Startle coloration- mimics eyes to look like larger, dangerous animals

o Chemical warfare o Aggressive mimicry- entice their prey to come close by resembling something attractive to the prey 27.4 What is parasitism?  Give a general definition of parasitism o One species benefits, while the other is harmed  Describe how parasites and their hosts act as agents of natural selection on each other o Cause mutations 27.5 What is mutualism?  Define mutualism and provide an example o Relationship benefits both species (ruminants) 27.6 How do keystone species influence community structure?  Define keystone species o Species whose influence on community structure is greater than its abundance would suggest  Explain how keystone species exert strong control on community structure. Describe an example. o If a keystone species is removed from its community, normal community interactions are significantly altered and the relative abundance of other species changes dramatically o Elephants maintain grasslands by eating trees and shrubs 27.7 Succession: how do community interactions cause change over time?  Define ecological succession and explain how environmental disturbances influence it o Succession is a structural change in a community and its nonliving environment over time o Succession is preceded and started by an ecological disturbance, an event that disrupts the ecosystem by altering its community, its abiotic structure, or both  Distinguish between primary and secondary succession o Primary succession  Starts on bare rock, barren environments  No previously establish ecosystem  Occurs over a longer period of time (thousands of years) o Secondary succession  Starts in a disturbed, established ecosystem  Plowed field, logged forest, etc.  Occurs over shorter time (hundreds of years)