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Chapter 50

BIOLOGY 1M03 Chapter Notes - Chapter 50: Biotic Component, Crypsis, Amazon River

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Jon Stone

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Chapter 50: An Introduction to Ecology
Ecology is the study of how organisms interact with their environment
Areas of Ecological Study
Organismal Ecology
oHow individuals interact with each other and their physical environment
oResearchers explore the morphological, physiological and behavioural
adaptations that allow individuals to live successfully in a particular area
oAlso focuses on physiological adaptations that allow individuals to thrive in
heat, drought, cold or other demanding physical conditions
oEx. Sockeye Salmon
After spending four or five years feeding and growing in the ocean,
salmon travel long distances to return to stream where they
Females create nests in the gravel stream bottom and lay eggs
Nearby males compete for the chance to fertilize eggs as they are
When breeding is finished, all adults die
oBiologists want to know how these individuals interact with their physical
surroundings and with other organisms in and around the stream
Which females get best nesting sites and lay most eggs
Which males are most successful in fertilizing eggs
How do individuals cope with transition from living in saltwater to
living in freshwater
Population Ecology
oA population is a group of individuals of the same species that live in the
same area at the same time
oBiologists focus on how the number of individuals in a population change
over time
oMathematical models of population growth have been used to predict the
future of particular salmon populations

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oMany salmon populations have declined as their habitats have become
dammed or polluted
oIf the factors that affect population size can be described accurately
enough, mathematical models can assess the impact of proposed dams,
changes in weather patterns, altered harvest levels or specific types of
protection efforts
Community Ecology
oA biological community consists of the species that interact with each
other within a particular area
oResearchers ask how species interact with each other and the
consequences of those interactions
May concentrate on predation, parasitism or competition
oBiologists might also analyze how groups of species respond to
disturbances such as fires, floods and volcanic eruptions
oEx. When they are at sea, salmon eat smaller fish and are themselves
hunted and eaten by orcas, sea lions, humans and other mammals
When they return to freshwater to breed, they are preyed on by
bears and bald eagles
In both habitats, they are subject to parasitism and disease
Ecosystem Ecology
oAn ecosystem consists of all the organisms in a particular region along
with non-living components
oThese physical or abiotic components include air, water and soil
oBiologists study how energy and nutrients cycle through the environment
oEx. Salmon form a link between marine and freshwater ecosystems
They harvest nutrients in the ocean and when they die and
decompose, they transport these molecules to streams
In this way, salmon transport chemical energy and nutrients from
one habitat to another
Conservation biology is the effort to study, preserve and restore threatened
populations, communities and ecosystems

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Ecologists study how interactions between organisms and their environments
result in a particular species being found in a particular area at a particular
population size
Conservation biologists apply these data to preserve species and restore
Types of Aquatic Ecosystems
An organism’s environment has both physical and biological components
The abiotic or physical components include temperature, precipitation,
sunlight and wind
The biotic components consist of other members of the organism’s own
species as well as individuals of other species
In aquatic ecosystems, water depth and rate of water movement qualify as
key physical factors that shape the environment
Water depth dictates how much light reaches the organisms that live in a
particular region
Water movement presents a physical challenge, it can sweep organisms off
their feet
Freshwater Environments
oLakes and Ponds
Ponds are small, lakes are large enough that the water in them
can be mixed by wind and wave action
Most occur in northern latitudes, formed in depressions that
were created by the scouring action of glaciers thousands of
years ago
Water depth
Littoral zone consists of the shallow waters along the
shore, where flowering plants are rooted
Limnetic zone is offshore and comprises water that
receives enough light to support photosynthesis
Benthic zone is made up of the substrate
Regions of the littoral, limnetic and benthic zones that
receive sunlight are part of the photic zone
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