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Chapter 55

Chapter 55 Study Guide

5 Pages
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Department
Biological Sciences
Course Code
BIOA02H3
Professor
Dr.Persaud

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Chapter 55 Community Ecology
Host sweet host
-floral nectar attracts pollinators, animals that plant relies on in order to reproduce
-extrafloral nectars are grown on their non-reproductive (vegetative parts) to attract ants to find
food and nesting sites
-ants patrol plants and attack herbivores, pathogens and competing plants
-mutualism exists between host plant and ant species
-ant-hosting plants depend on a single ant species
-plants ensure attraction of the right host species by controlling the composition of nectars
55.1 What Are Ecological Communities?
-community is the area where species live and interact with other biotic and abiotic factors
Communities are loose assemblages of species
2 theories about nature of communities
1. Communities are loose assemblages of species
-each species was individually distributed according to its unique interactions with physical
environment
2. Communities are tightly integrated
-communities in similar environments would have the same species composition unless they had
been recently disturbed
-different combinations of plant species are found at different locations
-species enter and drop out of communities independently over environmental gradients
-first theory is supported
-ecological communities are not assemblages of organisms if species move together as units
when environmental conditions change
-each species has unique interactions with its biotic and abiotic environments
The organisms in a community use diverse sources of energy
-trophic level consists organisms whose energy source has passed through the same number of
steps to reach them
-autotrophs get energy directly from sunlight
-consist a trophic level called photosynthesizers/ primary producers
-produce energy-rich organic molecules that other organisms consume
-heterotrophs consume energy from autotrophs
-herbivores (primary consumers) eat plants
-secondary consumers eat herbivores
-tertiary consumers eat secondary consumers
-detritivores (decomposers) eat dead bodies of organisms/ waste products
-omnivores obtain food from more than one trophic level
-food chain is a sequence of interaction between trophic level of a set of organisms
-food chain makes up food web that shows interaction of species in a community
www.notesolution.com
-communities have only 3-5 trophic levels
-loss of energy between trophic level is the reason for the few established level
-biomass is weight of living matter, also distribution of energy
-photosynthetic plants dominate in energy and biomass in terrestrial ecosystem
-biomass at primary producer level is wood
-biomass of herbivores is larger in grasslands than in forests in relative to biomass of plant
-dominant photosynthesizers in aquatic ecosystems are bacteria and protists
-high rates of cell division leads to smaller biomass
-energy ingested by organisms is eventually consumed by decomposers
-detritivores transform detritus (dead remains and waste products of organisms) into mineral
nutrients available to plants
55.2 What Processes Influence Community Structure?
-predation (parasitism): one harmed, the other benefits (+/- interactions)
-competition: 2 organisms use same resources that are insufficient to supply combined needs (-/-
interactions)
-mutualism: both participants benefit (+/+)
-commensalism: one participant benefits but the other is unaffected (+/0)
-amensalism: one participant is harmed but the other is unaffected (0/-)
-competitors are predators that share diets
-predators feed on many species of prey in the diet
Predation and parasitism are universal
-parasites are smaller than host
-feed on hosts without killing them
-microparasites are pathogenic viruses, bacteria, protists
-herbivores feed on plants without killing them
-predators of animals kill prey
Predator and Prey Populations Often Oscillate
-predators depress population of prey
-cause fluctuation in prey population densities
-predator-prey interactions may increase prey population
-growth of predator population lags behind growth in its prey populations
-population density fluctuation is common in environment with only a few species of predators
and prey
-oscillations are driven by predation and interactions between preys and their food supply
Predators may Restrict Species Ranges
-predators restrict habitat and geographic distribution of prey
Mimicry Evolves in Response to Predation
1. Batesian mimicry is when a palatable species mimic an unpalatable/ noxious one
2. Mullerian mimicry is when 2/ more unpalatable species converge to resemble on one another
www.notesolution.com

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Description
Chapter 55 Community Ecology Host sweet host -floral nectar attracts pollinators, animals that plant relies on in order to reproduce -extrafloral nectars are grown on their non-reproductive (vegetative parts) to attract ants to find food and nesting sites -ants patrol plants and attack herbivores, pathogens and competing plants -mutualism exists between host plant and ant species -ant-hosting plants depend on a single ant species -plants ensure attraction of the right host species by controlling the composition of nectars 55.1 What Are Ecological Communities? -community is the area where species live and interact with other biotic and abiotic factors Communities are loose assemblages of species 2 theories about nature of communities 1. Communities are loose assemblages of species -each species was individually distributed according to its unique interactions with physical environment 2. Communities are tightly integrated -communities in similar environments would have the same species composition unless they had been recently disturbed -different combinations of plant species are found at different locations -species enter and drop out of communities independently over environmental gradients -first theory is supported -ecological communities are not assemblages of organisms if species move together as units when environmental conditions change -each species has unique interactions with its biotic and abiotic environments The organisms in a community use diverse sources of energy -trophic level consists organisms whose energy source has passed through the same number of steps to reach them -autotrophs get energy directly from sunlight -consist a trophic level called photosynthesizers primary producers -produce energy-rich organic molecules that other organisms consume -heterotrophs consume energy from autotrophs -herbivores (primary consumers) eat plants -secondary consumers eat herbivores -tertiary consumers eat secondary consumers -detritivores (decomposers) eat dead bodies of organisms waste products -omnivores obtain food from more than one trophic level -food chain is a sequence of interaction between trophic level of a set of organisms -food chain makes up food web that shows interaction of species in a community www.notesolution.com
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