Ecology
description
Transcript of Ecology
Ecolo
gy
WHAT IS ECOLOGY?
Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer
Ecology is a science of relationships
Organism
Population
Community
Biosphere
Ecosystem
Organism - any unicellular or multicellular form exhibiting all of the characteristics of life, an individual.•The lowest level of organization
POPULATION a group of organisms of one species living in the same place at the same time that interbreed
Produce fertile offspring
Compete with each other for resources (food, mates, shelter, etc.)
Community - several interacting populations that inhabit a common environment and are interdependent.
Ecosystem - populations in a community and the abiotic factors with which they interact (ex. marine, terrestrial)
Biosphere - life supporting portions of Earth composed of air, land, fresh water, and salt water.•The highest level of organization
•All organisms found here
II. Biomes and Aquatic Life Systems
A. Biomes:Land portion of the biosphereDistinct climate and specific life-forms
adapted for life within that climate.Climate - long-term patterns of weather is
the primary factor determining the type of life
B. Aquatic life zones:Marine and Freshwater
15,000 ft10,000 ft5,000 ft
Coastalmountainranges
SierraNevadaMountain
GreatAmericanDesert
RockyMountains
GreatPlains
MississippiRiver Valley
AppalachianMountains
Coastal chaparraland scrub
DesertConiferousforest
Coniferousforest
Prairiegrassland
Deciduousforest
Average annual precipitaion
100-125 cm (40-50 in.)
75-100 cm (30-40 in.)
50-75 cm (20-30 in.)
25-50 cm (10-20 in.)
below 25 cm (0-10 in.)
Ecosystem Concepts and Components
Fig. 4.9, p. 76
C. Ecotone• Transitional zone between two
ecosystems• A mixture of species found in both
ecosystems as well as organisms that are unique to the ecotones.
Ecosystem Boundaries: Ecotones
Land zone Transition zone Aquatic zone
Numberof species
Species in land zoneSpecies in aquatic zone
Species in transition zone only
Fig. 4.10, p. 77
List the factors affect the survival of the organisms in this aquarium?
WHAT DO YOU MEAN BY ENVIRONMENT?
The environment is made up of two factors:
• Biotic factors- all living organisms inhabiting the Earth
• Abiotic factors- nonliving parts of the environment (i.e. temperature, soil, light, moisture, air currents)
Abiotic Factors
• The non living factors, called abiotic , are the physical and chemical characteristics of the environment
• Examples: Temperature, humidity, pH, salinity, oxygen concentration, amount of sunlight, available nitrogen, and precipitation
Habitat vs. NicheNiche - the role a species plays in a community; its total way of life
Habitat- the place in which an organism lives out its life
Habitat vs. NicheA niche is determined by the tolerance limitations of an organism, or a limiting factor.
Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.
•Each population has a “Range of Tolerance” to abiotic factors.•These are the minimum and maximum levels that can be tolerated by an organism. *Limiting Factors of Water;
D.O. SalinityLight Penetration Nutrients
*Limiting Factors of Land;Precipitation Temp.Latitude Sunlight
A. Major Non-Living Components
Examples of limiting factors -
•Amount of water•Amount of food•Temperature•Amount of space•Availability of mates
Habitat vs. Niche
Popu
latio
n si
ze
Low High Temperature
Zone ofintolerance
Zone ofphysiological stress
Optimum range Zone ofphysiological stress
Zone ofintolerance
Noorganisms
Feworganisms
Lower limitof tolerance
Abundance of organismsFew
organismsNo
organisms
Upper limitof tolerance
Feeding Relationships• There are 3 main types of
feeding relationships1. Producer - Consumer
2. Predator - Prey3. Parasite - Host
Feeding RelationshipsProducer- all
autotrophs (plants), they trap energy from the sun
• Bottom of the food chain
Feeding RelationshipsConsumer- all heterotrophs:
they ingest food containing the sun’s energy
HerbivoresCarnivoresOmnivoresDecomposers
Feeding Relationships
CONSUMERS 1. Primary
consumers• Eat plants• Herbivores
• Secondary, tertiary … consumers
• Prey animals• Carnivores
Feeding RelationshipsConsumer-Carnivores-eat
meat• Predators
–Hunt prey animals for food.
Feeding RelationshipsConsumer- Carnivores- eat
meat• Scavengers
–Feed on carrion, dead animals
Feeding Relationships
Consumer- Omnivores -eat both plants and animals
Feeding Relationships
Consumer- Decomposers
• Breakdown the complex compounds of dead and decaying plants and animals into simpler molecules that can be absorbed
Symbiotic RelationshipsSymbiosis- two species living
together3 Types of symbiosis:1. Commensalism2. Parasitism3. Mutualism
Symbiotic RelationshipsCommensalism-
one species benefits and the other is neither harmed nor helped
Ex. orchids on a treeEpiphytes: A plant, such as a tropical orchid or a bromeliad, that grows on another plant upon which it depends for mechanical support but not for nutrients. Also called xerophyte, air plant.
Symbiotic RelationshipsCommensalism-
one species benefits and the other is neither harmed nor helped
Ex. polar bears and cyanobacteria
Symbiotic RelationshipsParasitism- one species benefits (parasite)
and the other is harmed (host)
• Parasite-Host relationship
Symbiotic RelationshipsParasitism- parasite-hostEx. lampreys, leeches, fleas,ticks, tapeworm
Symbiotic RelationshipsMutualism-
beneficial to both species
Ex. cleaning birds and cleaner shrimp
Symbiotic RelationshipsMutualism-
beneficial to both species
Ex. lichen
• This relationship enables each to tolerate harsh conditions where neither could survive alone. In this partnership, the fungus furnishes the alga with water, prevents overexposure to sunlight, and provides simple mineral nutrients, while the photosynthesizing alga supplies food to the fungus even if no other organic material is available.
Type of relationship
Species harmed
Species benefits
Species neutral
CommensalismParasitism
Mutualism
= 1 species
Trophic Levels
• Each link in a food chain is known as a trophic level.
• Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.
Trophic LevelsBiomass- the amount of organic
matter comprising a group of organisms in a habitat.
• As you move up a food chain, both available energy and biomass decrease.
• Energy is transferred upwards but is diminished with each transfer.
Trophic Levels
Producers- Autotrophs
Primary consumers- Herbivores
Secondary consumers-small
carnivores
Tertiary consumers-
top carnivores
ENERGY
Pyramid of Energy – Diagram used to show the flow of energy from one trophic level to another.
Ecological Efficiency:• % of usable energy transferred from level to
level• Typically 5-20%• Measured as Biomass – the dry weight of tissue
and other organic matter
The shape of the Pyramid of Energy Flow Explains why:
1.) So few top carnivores2.) Why these species are the first to suffer when
there is disruption3.) Why they are vulnerable to extinction
Trophic LevelsFood chain- simple model
that shows how matter and energy move through an ecosystem
Trophic Levels
Food web- shows all possible feeding relationships in a community at each trophic level
• Represents a network of interconnected food chains
Food chain Food web(just 1 path of energy) (all possible energy
paths)
Nutrient CyclesCycling maintains homeostasis (balance) in the environment.
•5 cycles to investigate:1. Water cycle2. Carbon cycle3. Nitrogen cycle4. Phosphorus5. Oxygen
Water cycle-
•Evaporation, transpiration, condensation, precipitation
Water cycle-
Carbon cycle-
•Photosynthesis and respiration cycle carbon and
oxygen through the environment.
Carbon cycle-
Nitrogen cycle- Atmospheric nitrogen (N2) makes up nearly 78%-80% of air. Organisms can not use it in that form.Lightning and bacteria convert nitrogen into usable forms.
Nitrogen cycle- Only in certain bacteria and industrial technologies can fix nitrogen.Nitrogen fixation-convert atmospheric nitrogen (N2) into ammonium (NH4
+) which can be used to make organic compounds like amino acids.
N2 NH4+
Nitrogen cycle-Nitrogen-fixing bacteria:Some live in a symbiotic relationship with plants of the legume family (e.g., soybeans, clover, peanuts).
Nitrogen cycle- •Some nitrogen-fixing bacteria live free in the soil.
•Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies.
Atmospheric nitrogenLightning
Nitrogen fixing
bacteria
Ammonium Nitrification by bacteria
Nitrites Nitrates
Denitrification by bacteria
Plants
Animals
Decomposers
Nitrogen Cycle
Phosphorus Cycle
Phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean.
Oxygen Cycle
• A plant does photosynthesis to let off Oxygen for organisms to use
• The humans use up the oxygen through respiration and let off CO2.
• The CO2 is then passed from the humans to the plants again.
Toxins in food chains- While energy decreases as it moves up the food chain, toxins increase in potency. •This is called biological magnification
Ex: DDT & Bald Eagles
Population Dynamics• The study of short‐ and long‐term
changes in the number of individuals for a given population, as affected by birth, death, immigration, and emigration
• birth, death, immigration, and emigration.
Battle at Kruger
• Kruger National Park is one of the largest game reserves in Africa. It covers an area of 19,485 square kilometres (7,523 sq mi)
• http://www.youtube.com/watch?v=LU8DDYz68kM
I. Population Dynamics
A. Characteristics of a population
1. Size - number of individuals2. Density - number of
individuals per space3. Age Distribution – portions
of individuals of each age
4. Dispersion – spatial patterns of organisms
B. Factors that govern population size
Births
Emigration
Immigration
Deaths
Models for Population Growth RatesA. Exponential Growth Model:
Observed in populations with few or no resource limitations.
Starts slow and then increases “J-shaped curve”
CHOICE B
• $18,446,74 4,073,709,551,615 dollars!!
Exponential Growth
Exponential Growth (J-shape Curve)
Often described in terms of…1. Biotic Potential: How large a population could grow to if there were unlimited
resources
Populations typically can’t grow exponentially forever.
2. Environmental Resistance:All of the living and non-living factors working to hold a population size down.
Carrying Capacity “K”Number of individuals of a given species that can be
sustained in a given space indefinitelyDetermined by biotic potential and environmental resistance
working against each other
2.0
1.5
1.0
.5
Num
ber
of sh
eep
(mill
ions
)
1800 1825 1850 1875 1900 1925
Populations can Crash
• Limiting factors restrain the growth of a population
• As the population grows, competition for resources increases. Thus, reproduction shrinks over time.
• This may lead to species extinction
Reindeer in Alaska
Fig. 9.6, p. 201
2,000
1,500
Num
ber o
f rei
ndee
r
1910 1920 1930 1940 1950
Year
1,000
500
http://www.youtube.com/watch?v=-hO-vCPuuQQ
http://www.youtube.com/watch?v=gfbQA-Krx9Q
What is Ecological Succession?
• Natural, gradual changes in the types of species that live in an area
• Can be primary or secondary • The gradual replacement of
one plant community by another through natural processes over time
Primary Succession• Begins in a place without any
soil: »Sides of volcanoes»Landslides»Flooding
• First, lichens that do not need soil to survive grow on rocks
• Next, mosses grow to hold newly made soil
• Known as PIONEER SPECIES
Pioneer Species
Lichens break down rock to form soil.
Low, growing moss plants trap
moisture and prevent soil
erosion
Primary Succession• Simple plants like mosses and
ferns can grow in the new soil
Primary Succession• The simple plants die, adding
more organic material (nutrients to the soil)
• The soil layer thickens, and grasses, wildflowers, and other plants begin to take over
Primary Succession• These plants die, and they add
more nutrients to the soil• Shrubs and trees can survive
now
Secondary Succession• Begins in a place that
already has soil and was once the home of living organisms
• Occurs faster and has different pioneer species than primary succession
• Example: after forest fires
Climax Community• A stable group of plants
and animals that is the end result of the succession process
• Does not always mean big trees–Grasses in prairies–Cacti in deserts