Download Ecology

Ecology
Behavior, Communities,
Ecosystems
 Behavioral
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ecology
Scientific study of behavior in natural
environments from an evolutionary
perspective
Behavior
• What an animal does
• How it does it
• Usually in response to stimuli from the
environment
 Cost-benefit
analysis to determine
whether a behavior is adaptive
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Contribute to direct fitness
Animal’s reproductive success
measured by the number of viable
offspring
When benefits outweigh costs, behavior
is adaptive
 Behavior
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Results from the interaction of innate
behavior and environmental factors
Learned behavior
• Behavior is modified in response to
environmental experience
Imprinting
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Establishes a parent-offspring bond
Ensures that the offspring recognizes
the parent
 Selfish
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behavior
Increases individuals chances of
survival
Social groups; selfish herd; dominance
hierarchies
 Altruistic
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behavior
Sacrifice for the good of the group
Bees
Inclusive fitness – passing on the genes
that make organism care for relatives
 Social
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behavior
Adaptive interaction, usually among
members of the same species
Animal communication involves exchange
of recognizable signals
Pheromones are chemical signals that
convey information between members of
a species
Are mating and parental behavior
under genetic influence?
 Those
that can attract more mates,
reproduce more, pass on those genes
 Parenting is an energy consuming role,
but it ensures offspring survive to pass on
genes
What is the relationship between
ecology and evolution?
 The
reason species evolve is due to
environmental pressures

Food is scarce – maybe better digestive tract
or teeth help some survive – they pass on
those traits
5 factors that shape community
structure
 Interaction
between climate and
topography
 Food
 Adaptive traits of species
 Species interactions
 Pattern of population size
 Ecological
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niche
Distinctive lifestyle and role of an organism in
a community
Takes into account all abiotic and biotic
aspects
For example, an organism’s habitat is one
parameter used to describe the niche
 Interspecific
competition – between 2
populations

Requirements of 2 species are close, but
never exactly the same
 Competitive
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exclusion principle
Two species cannot occupy the same niche
in the same community for an indefinite
period
One species is excluded by another as a
result of competition
Resource
partitioning
 Predation
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Defenses
Camouflage
Warning coloration
Mimicry
Moment of truth
Predator response to prey
Mimicry
Camouflage
 Symbiosis
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Mutualism
• Both partners benefit
Commensalism
• One partner benefits and the other is
unaffected
Parasitism
• One partner benefits while the other
is harmed
 Keystone
species
 Present in small numbers but are
crucial in determining the species
composition and ecosystem
functioning
• Beaver – creates new ecosystems
that animals rely on
 Dominant
species
 Affect the community because they
are so common
 Ecological
succession
 Primary succession
• Occurs in an area not previously
inhabited
 Secondary succession
• Occurs where there is a preexisting community and wellformed soil
Energy flow through an ecosystem
 Ecological
pyramids
 Express the progressive reduction
in numbers of organisms, biomass,
and energy found in successive
trophic levels
Biomagnification
 Gross
primary productivity (GPP)
 Rate at which photosynthesis
captures energy
 Net primary (ecosystem) productivity
(NPP)
 Energy that remains after plants
and other producers carry out
cellular respiration
 Carbon
cycle
 Carbon dioxide is the most
important gas
 Carbon enters plants, etc., as CO2
 Cellular respiration, combustion,
and erosion of limestone return
CO2 to the environment
 Nitrogen

cycle
Five steps
• Nitrogen fixation – converting N2 to
ammonia
• Nitrification – convert ammonia to
nitrates (which plants use)
• Assimilation – nitrogen taken by
organism to make organic
compounds
• Ammonification – ammonia ions
• Denitrification – ammonia to N2
 Hydrologic
cycle
 Renews the supply of water
 Involves an exchange of water
between the land, ocean,
atmosphere, and organisms
 Water enters the atmosphere by
evaporation and transpiration
 Water leaves the atmosphere as
precipitation