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Chapter 50, 51, 52, 53, 54, 55

BIOLOGY 1M03 Chapter 50, 51, 52, 53, 54, 55: Bio 1M03


Department
Biology
Course Code
BIOLOGY 1M03
Professor
Jon Stone
Chapter
50, 51, 52, 53, 54, 55

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Chapter 50 – An Introduction to Ecology
Ecology: the study of how organisms interact with their environment, goal to understand the
distribution and abundance of organisms
-Key Concepts
oEcology’s goal is to explain the distribution and abundance of organisms. It is the
branch of biology that provides a scientific foundation for conservation efforts
oPhysical structure – particularly water depth – is the primary factor that limits the
distribution and abundance of aquatic species. Climate – specifically, the average
value and annual variation in temperature and in moisture – is the primary factor
that limits the distribution and abundance of terrestrial species
oClimate varies with latitude, elevation and other factors – such as proximity to
oceans and mountains. Climate is changing rapidly around the globe
oA species’ distribution is constrained by historical and biotic factors, as well as by
abiotic factors such as physical structure and climate
-4 main levels of ecology
oOrganismal Ecology
Explore the morphological, physiological and behavioural adaptations that
allow individuals to live in a particular area
How do individuals interact with each other and their physical
environment?
Ex. Salmon migrate from saltwater to freshwater environments to breed
oPopulation Ecology
Focus on how the numbers of individuals in a population change over time
How and why does population size change over time?
Ex. Each female salmon produces thousands of eggs but only a few will
survive to adulthood
oCommunity Ecology
Nature of interactions between species and consequences between those
actions
oEcosystems Ecology
An extension of organismal, population and community ecology
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An ecosystem consists of all the organisms in a particular region along
with nonliving components (abiotic)
Study how nutrients and energy move among organisms and through the
surrounding atmosphere and soil or water
-Conservation biology: the effort to study, preserve and restore threatened populations,
communities and ecosystems
o4 levels of ecological study are synthesized and applied in conservation biology
-Nutrient Availability
oIn many aquatic ecosystems, nutrients such as nitrogen and phosphorus are in
short supply, washed away or at the bottom
-Ocean upwelling
oProcess in which deep, cold water rises towards the surface
oWind blowing across the ocean surface push water away
oWater rises up from beneath surface to replace water
oUpwelling water is nutrient rich
-Lake Turnover
oSpring and fall lake turnovers
oOccurs in response to changes in air temperature
oWithout the spring and fall turnovers, most freshwater nutrients would remain on
the bottom of lakes
oWater is most dense at 4 degrees Celsius
1) Winter Stratification
-Dense at 4 degrees, water at the bottom becomes nutrient rich while colder
water near surface becomes oxygenated
-Thermocline: gradient in temperature
2) Spring Turnover
-Surface water warms to 4 degrees Celsius and sinks, carrying oxygen
down and driving nutrients up
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-Flush of nutrients triggers a rapid increase in the growth of photosynthetic
algae and bacteria that biologists call the spring bloom
3) Summer Stratification
-Dense 4 degrees water at bottom becomes nutrient rich
-Warmer water near surface becomes oxygenated
4) Fall Turnover
-Surface water cools to 4 degrees and sinks, carrying oxygen down and
driving nutrients up
-Water Flow
-A critical factor in aquatic ecosystems because it presents a physical challenge: it
can literally sweep organisms away
-Water Depth
-Water absorbs and scatters light, so the amount and types of wavelengths
available to organisms change dramatically as depth increases
-Light has a major influence of productivity – the total amount of carbon fixed by
photosynthesis per unit area per year
-5 different zones of water depth in lakes and ponds:
Littoral (“seashore”) zone: consists of the shallow waters along
the shore, where plants are rooted
Limnetic (“lake”) zone: offshore and comprises water that
receives enough light to support photosynthesis
Benthic (“depths”) zone: made up of substrate
Photic zone: regions of the littoral, limnetic and benthic zones that
receive sunlight
Aphotic zone: portions of a lake or pond that do not receive
sunlight
-Wetlands: shallow water habitats where the soil is saturated with water for
at least part of the year
-Presence of “indicator” plants that grow only in saturated soils
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