packet #81 chapters #54 & #50 community ecology. review & introduction community assemblage...
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PACKET #81CHAPTERS #54 & #50
Community Ecology
Review & Introduction
Community Assemblage of
populations, of different species, that live and interact in the same place at the same time
Community Ecology Description and
analysis of patterns and processes within the community
Introduction II
Communities are difficult to study Large number of organisms and many different
species that interact with one another and are interdependent in a variety of ways Species compete for food, water, living space and other
resources Communities vary in size Lack precise boundaries Rarely completely isolated Within a community, no species exists independently
of other species.
COMMUNITY STRUCTURE & FUNCTIONING
Community Ecology
Niche
The role of a species within a community
Describes all aspects of an organism’s existence Not only habitat, but
much moreFundamental Niche
Niche that an organism would occupy in the absence of competition
Realized Niche Niche that an organism
occupies in the presence of competition
Niche II
Limiting resources restrict the ecological niche of a species Soil composition Climatic extremes Any environmental resource that is scarce or
unfavorable
Biotic and abiotic factors may influence an organism’s niche
Competition
Intraspecific Competition between
members of same species Interspecific
Competition between members of different species
Competition between two species with overlapping niches may lead to competition exclusion Results in the exclusion of
one species due to interspecific competition
Coexistence occurs when overlap between niches is reduced
Natural Selection
DEFENSE MECHANISMS
Community Ecology
Defense MechanismsHiding
Use of warning colors Aposmatic Colors
A warning coloration such as a 'striking' color pattern designed to attract attention and to warn predators away.
Defense MechanismsHiding
Batesian mimicry Resemblance of a
harmless organism to a harmful or unpalatable organism
Defense MechanismsHiding
Mullerian mimicry Similar morphology of
a group of harmful or unpalatable organism Monarch & Viceroy
butterflies
Symbiosis
Any intimate relationship or association between members of two or more species Greek sym = together Greek bios = life
Types of Symbiosis I
Mutualism Benefits are shared
Nitrogen fixing bacteria & legumes
Zooxanthellae and reef-building coral
Mycorrhizae facilitate mutalistic relationships between fungi and the roots of a wide variety of plants
Types of Symbiosis II
Commensalism Taking without harm
Epiphytes living on tropical tress benefit from the habitat of the host, but the host is not harmed or benefited
Types of Symbiosis III
Parasitism Taking at another’s
expense Parasite benefits while
host is harmed Well adapted parasite
does not kill the host Parasite that causes
the death of the host is a pathogen
Keystone Species
Affect the character of the communityHave a great effect on other species in the
community Commonly are the top predators
Dominant species influence the community as a result of their greater size or abundance Trees are the dominant species in forests because
they change the local environment Coral, an animal, in coral reefs
COMMUNITY DEVELOPMENT
Community Ecology
Succession
Process of community development over time, with one species being replaced by another
Succession II
Primary Succession Occurs when a
community develops in a “lifeless” environment Occurs on bare rock
when rock is eventually transformed into soil
Occurs on newly formed volcanic larva and recently glaciated rock
Succession III
Secondary Succession Occurs when a
community develops where a previous community existed
Occurs where soil already exists Areas denuded or
modified by fire or agriculture
Abandoned farmlandKeep in mind that
disturbances impact succession
Studying Succession
Ecologists continue to study community structure
Clements Developed organismic model
Emphasizes the interdependence of species within the community
Gleason Developed individualistic model
Emphasizes species individually Most research is conducted here
Review
Review
Students are encouraged to place their own questions and charts on the following slides.