Ecology, Ecosystems, and Population Dynamics

ECOLOGY: the study of the interactions between living things and their environments

Ecological Hierarchy

Population• A group of individuals that interbreed and

therefore share the same gene pool• A population can evolve as the individuals’

offspring undergo changes in phenotype and genotype

Community • A group of populations that live in a particular

environment that interact with one another in many different ways

Niche• The way an organism lives in its environment,

including its nesting behavior, what type of food it eats, and where it hunts

• Competition between populations in similar niches drives evolution

Community Roles• Producers: have all of the raw

building blocks to make their own food; convert light energy to chemical energy via photosynthesis

• Consumers: forced to find their energy sources in the outside world; digest the carbs of their prey to make organic substances

• Decomposers: break down organic matter into simple products; fungi and bacteria serve as the “garbage collectors” of the environment

• Ecosystem: Self contained region that include both living and nonliving factors; there is an exchange of materials between the components of an ecosystem

• Carbon Cycle: the way carbon is recycled through an ecosystem

Biomes• Massive areas that are classified on the basis

of their climates and plant life; usually arranged along particular latitudes

Types of Biomes

Tundra• Northernmost regions• Grasses/wildflowers; few trees• Contains permafrost• Arctic foxes, snowy owls, reindeer

Types of Biomes

Taiga• Northern forests• Wind blown conifers, stunted in growth with

spikes• Very cold long winters• Caribou, wolves, moose, bears, rabbits, and

lynx

Types of Biomes

Temperate Deciduous Forrest• Northeast and Mideast US, Western Europe• Deciduous trees that drop their leaves in

winter• Moderate precipitation, warm summers, cold

winters• Deer, wolves, bears, small mammals, birds

Types of Biomes

Grasslands• Midwest. US, Eurasia, Africa, South Africa• Grasses• Hot summers, cold winters; unpredictable rain• Prairie dogs, bison, ferrets, grouse, lizards

Types of Biomes

Deserts• Western US• Sparse, includes cacti, drought-resistant plants• Arid, low rainfall, extreme diurnal

temperature shifts• Owls, kangaroos, snakes

Types of Biomes

Tropical Rainforests• South America• High biomass, diverse plant life• High rain and temperatures, impoverished soil• Snakes, monkeys, birds, leopards, insects

Biosphere

• The entire part of the earth where living things exist, including soil, water, light and air

• Relatively small in comparison to overall mass of earth

Food Chain• Tertiary consumer- eat everything• Secondary consumer: feed on primary consumers and producers• Primary consumers: feed directly on producers• Producers (Autotrophs): produce all available food; possess the

highest biomass (total weight of all the organisms in an area) and the greatest numbers

• Decomposers are not considered part of food chain; can decompose ANY organism

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The 10% Rule• Only about ten percent of the energy is transferred

from one level to the next, with other 90 percent being used for respiration, digestion

• In an ecosystem, tertiary= least energy, producers = most energy

Ecological Pyramid: Represents the energy flow, biomass, and numbers of members within an ecosystem; higher up pyramid = less biomass and energy

Symbiotic Relationships

Mutualism: both organisms benefit

Commensalism: one organism lives off another with no harm to the host

Parasitism: the organism actually harms its host

Population Ecology: the study of how populations change, looking at size, density, distribution patterns, and age structure

Survivorship Curves

• Graphs showing number of individuals living to different ages, indicating probability of an individual living to an age

• R= (births – deaths)/ N, where R is the reproductive rate, N is population size

Life History StrategiesR-selected organisms: live in unstable

environments and multiply before competitors arrive to produce a lot of offspring; e.g. dandelions and mice

K-selection: stable environments; produce only a few offspring; equipped to deal with competition;

e.g. redwood trees and human beings

Exponential growth

Ideal, unrestricted growth because of unlimited resources

Logistic growth

In actuality, at some point the population size becomes restricted by limited resources

Carrying Capacity

The maximum population size that a particular environment can sustain

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• Density Independent: affects the population regardless of density of population; e.g. severe storms, extreme climates

• Density Dependent: depends on population density; e.g. resource competition/depletion and predation

Limiting Factors

ECOLOGICAL SUCCCESSION: The predictable procession of plant communities over a relatively short period of time

Primary Succession: the process of ecological succession where no organisms

previously existed

Sere: entire sequence of different plant communities

Pioneers: make the area more habitable, setting the stage for other organisms

Climax community: the final community

Secondary Succession: when a new community develops where another community has been destroyed or disrupted (e.g. after a fire)

HUMAN IMPACT ON ENVIRONMENT

Greenhouse Effect: increases atmospheric competition of carbon dioxide through burning of fossil fuels and forests; causes warming of earth

Acid Rain: burning of fossil fuels produces sulfur dioxide and nitrogen dioxide, which react with water in clouds to produce rain that lowers pH of aquatic ecosystems and soil

Desertification: when land is overgrazed by animals

HUMAN IMPACT ON ENVIRONMENT

Deforestation: clearing of forests causes erosion, floods, weather pattern changes

Pollution: as toxins move up tropic levels, they become more concentrated by biomagnification

Reduction in biodiversity: different habitats are destroyed, causing plants and animals to become extinct; ecosystem becomes more vulnerable to changes and threats

HUMAN IMPACT ON ENVIRONMENT

• http://www.tutorvista.com/content/biology/biology-iv/organisms-environment/organism-and-environment.php

• http://eo.ucar.edu/kids/green/cycles6.htm• http://vcebiology.edublogs.org/category/population/• http://en.wikipedia.org/wiki/File:Survivorship_Curves.jpg• http://worldslife-nisha.blogspot.com/2011_06_01_archive.html• http://www.greenbusgroup.com/human-ecology.html• http://ocw.tufts.edu/Course/21• http://laurenyoung3b.edublogs.org/2012/04/27/levels-of-organization-in-an-environment/• http://fitz6.wordpress.com/2012/01/09/producers-and-consumers/• http://cikgurozaini.blogspot.com/2011/09/ecosystem.html• http://www.marietta.edu/~biol/biomes/biome_main.htm• http://www.blueplanetbiomes.org/tundra.htm• http://www.plantsystematics.org/reveal/pbio/biome/lec35a.html• http://www.marietta.edu/~biol/biomes/tempded.htm• http://www.blueplanetbiomes.org/grasslands.htm• http://www.proprofs.com/quiz-school/story.php?title=identifying-biomes• http://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=9683• http://www.kidsgeo.com/geography-for-kids/0162-food-chains.php• http://www.transtutors.com/homework-help/biology/living-organism-and-environment/

commensalism.aspx• http://www.cbu.edu/~seisen/ExamplesOfParasitism.htm• http://math.tutorvista.com/algebra/exponential-growth.html• hann1900.tripod.com• http://www.globalchange.umich.edu/globalchange1/current/lectures/competition/competition.html• http://www.icarda.org/HomePageStory/Desertification.htm• Princeton Review: AP Biology Exam 2012