Ecology Exam Review

Abiotic
•Temp•Light•Water•Wind•Nutrients
Factorsinfluencing popstructure &process:
•Extinction•Distribution•Growth
Landscape Ecology
The study of theexchanges of materials,energy or organismsamong ecosystems
Boreal or Taiga
dominated by black spruce; cold climate;moist soils)
Arctic tundra
(small plants & no trees, poorly developedsoils
Desert
hot, low soil moisture, sandy soils
Tropical Rain Forest
wet, warm; very biologically diverse
Climate
is defined as the average weatherpattern over a long period of time at a particularlocation, normally in terms of temperature andprecipitation.Toronto’s climate: cold winters, warm summers,approx.

900 mm of precipitation per year.

Weather
is defined as the meteorologicalconditions at a point in time (weather forecast fortoday is cloudy, warm, windy, with 30% chanceof precipitation, etc)
What affects distribution ofclimate around the earth?
Spherical shape of the earth and tilt of earth’saxis cause uneven heating of earth’s surface.Uneven heating drives major global aircirculation patterns and consequentlyprecipitation and biome distribution patterns.

Tropical Hadley Cell in northern hemisphere
Circulation pattern in cell caused by:• Warm, moist air rises.• Moisture cools, condenses, and falls asrain.• Some of the dry ascending air travelsnorthward. Then cooler, dry air falls back to surface.Once air has been set in motion, it undergoes anapparent deflection from its path, as seen by anobserver on the earth. This apparent deflectionis called the “Coriolis force” and is a result of the earth’s rotation or daily spin.

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–deflected to the right in northern hemisphere and left in southern

Major water (moisture) pools
– Clouds/atmospheric moisture– Rivers, streams, glaciers– Groundwater– Oceans
Controls of aquatic organism distributions
temperature- salinity- physical conditions (light, current)- water chemistry (nutrients, acidity)
Spontaneous generation
anearly hypothesis used to explainhow species arose
Special creation
cannot betested (based on faith, notobservation) and thereforeoutside the realm of science
Lamarck
inheritance ofacquired characteristics ofindividuals
Gregor Mendel
characteristicspass from parent to offspring in theform of discrete packages (genes).Genes come in alternative forms= alleles
Gregor Mendel
characteristicspass from parent to offspring in theform of discrete packages (genes).Genes come in alternative forms= alleles
Genotype
genes (DNA) of anorganism for a particular trait or traits,which may or may not be expressed
Phenotypic
visibleexpression of a genotype
Variation
•Variation exists in populations•Some variation has a genetic basis& is therefore inheritable•Variation can be neutral, beneficialor detrimental•All genetic variation arises bychance
Excess offspring
All species have the capacity toproduce more offspring than cansurvive to reproduction
Competition
There is competition amongindividuals in a population for thelimited resources
Natural Selection
Some individuals will be successful atobtaining enough resources andsurviving to reproduction & producingoffspring. Others will not.
Allele frequency
Natural selection on phenotypesresults in changes in allelefrequency from generation togeneration.
Changing environment
As the environment changes,organisms over time adapt to localenvironment
Speciation
•The origin of species•Speciation can be an outcome ofevolution – when a populationchanges sufficiently over time
Genetic Drift
Mechanism of evolution due to random changes in the allelic frequencies of apopulation
What limits population growth
Density – dependent factors:•Disease•Predation•Competition•Behavioral
Richness
number of species
Evenness
– relative abundance in a community
Shannon-Wiener Index:
•Index of species diversity•Takes into account both richness &evenness
Limits to population growth Density – dependent factors:
•Disease•Predation•Competition•Behavioral
limits to population growth, Independent Factors
•Floods•Extreme temperatures
Intraspecific competition
competition –compete with members of ownspecies (conspecifics)
Interspecific competition
compete with other species
Interference Competition
direct aggressive interactionbetween individuals
Exploitative Competition
accessto resources without directaggressive interactions (e.g.,some forms of territoriality)
Competitive Exclusion Principle
States that no two species withidentical ecologies can coexistOr• Two species with similar needsfor the same limiting resourcecannot coexist
Fundamental Niche
physicalconditions under which a speciesmight live in the absence ofinteractions of other species
Realized Niche
interactions that may restrict theenvironments in which a specieslives
Character Displacement
tendency for characteristics oftwo species to be more different inan area of sympatry than when theyare allopatricSympatry – in the same place• Allopatry – in different regions
BATESIAN MIMICRY
Occurs when one organism which isharmless (the mimic which does nottaste disgusting or sting) looks like onethat is harmful (the model).
MULLERIAN MIMICRY
Occurs whenseveral nastytasting orstingingorganismsevolve to looklike oneanother
Symbiosis
close interactionsbetween species
Commensalism
one speciesbenefits the other neitherbenefits or harmed
Facultative
can live withoutpartnership
Obligate
Obligate – cannot live inabsence of partnership
Primary Productivity
Primary production: Fixation ofenergy by autotrophs in anecosystem
Organisms and LandscapeStructure
African elephants knock down tress– Change woodland to grasslandKangaroo Rats dig burrow systemsthat modify soil structure and plantdistributions