Transcript SB4a LEQ1 Relationships Fall 2008

Unit 3 Ecology
SB4. Students will assess the
dependence of all organisms on one
another and the flow of energy and
matter within their ecosystem.
a. Investigate relationships
among organisms, populations,
communities, ecosystems, and
biomes.
LEQ1: What relationships
exist among organisms,
populations, communities,
ecosystems, and biomes?
Relationships
• Ecology is the study of relationships among
organisms and their environment.
– Interactions between living things and their
environment
– Interactions among living things
Relationships
• Ecologists study the environments
different levels of organization.
– Organism
– Population
– Community
– Ecosystem
– Biome
– Biosphere
Relationships
• An organism is an individual living thing, such as an
alligator.
– Species: group of similar organisms that can breed
and produce fertile offspring.
Organism
Organism
Relationships
• A population is a group of the same species that lives in
one area.
Population
Population
Organism
Organism
Relationships
• A community is a group of different species that live
together in one area
Community
Population
Community
Population
Organism
Organism
Relationships
• An ecosystem includes all of the organisms as well as the
climate, soil, rocks, water, and other nonliving things in a
given area.
Ecosystem
Community
Population
Ecosystem
Community
Population
Organism
Organism
Relationships
• A biome is a major regional or global community if
organisms characterized by the climate conditions and
plant communities that thrive there.
Biome
Ecosystem
Community
Population
Ecosystem
Community
Population
Organism
Organism
Relationships
• The biosphere contains the combined portions of the
planet in which all of life exists.
Biosphere
– All biomes (land, water, air)
Biome
– The entire planet
Ecosystem
Ecosystem
Community
Community
Population
Population
Organism
Organism
Ecologist Study Relationships
• Observation
– Direct Survey
• Used for easy to spot species
– Indirect Survey
• Used for species that are
difficult to spot or track
• Look for signs of their
presence.
Relationships
• Experimentation
– Conducted in lab which
gives researchers more
control
– Conducted in the field
which is a more accurate
account of natural
interactions
Relationships
• Modeling
– Allows scientists to learn about organisms or
ecosystems in ways that would not be possible in a
lab or natural setting
• Use computer and mathematical models
Ecologists use data transmitted
by GPS receivers worn by
elephants to develop computer
models of the animal’s
movements.
Biotic and Abiotic Factors
• Every ecosystem includes both living and
nonliving factors
Biotic and Abiotic Factors
• Biotic factors are living things.
– Plants
– Animals
– Fungi
– Bacteria
Plants
Biotic and Abiotic Factors
• Abiotic factors are nonliving things
– Moisture
– Temperature
– Wind
– Sunlight
– soil
Sunlight
Moisture
Biotic and Abiotic Factors
• Changing one factor is an ecosystem can
affect many other factors
– Biodiversity is the assortment, or variety, of
living things in an ecosystem.
– Rain forests have more biodiversity than other
locations in the world, but are threatened by
human activities
Biotic and Abiotic Factors
• A keystone species is a species that has
an unusually large effect on its ecosystem.
– They form and maintain a complex web of life
keystone
Biotic and Abiotic Factors
creation of
wetland
ecosystem
increased waterfowl
Population
keystone species
increased
fish
population
nesting sites
for birds
Habitat and Niche
• Every organism has a habitat and a niche.
Habitat and Niche
• A habitat differs from a niche.
• A habitat is all aspects of the area in which
an organism lives
– Biotic factors
– Abiotic factors
• Your address
Habitat and Niche
• An ecological niche includes all of the
factors that a species needs to survive,
stay healthy, and reproduce
– Food
– Abiotic conditions
– Behavior
• Your occupation
Habitat and Niche
• Species can share habitats but cannot
occupy the same niche in the same
ecosystem.
• Competition occurs when two species use
resources in the same way (occupy same
niche)
• Competitive exclusion keeps two species
from occupying the same niche.
Habitat and Niche
Competitive exclusion has three different outcomes:
1. One species is better suited to the niche and the
other will either be pushed out or become extinct.
2. The niche will be divided.
3. The two species will further diverge.
Habitat and Niche
• Ecological equivalents are species that
occupy similar niches but live in different
geographical regions.
Madagascar
South America
Community Interactions
• Organisms interact as individuals and as
populations
Community Interactions
• There are three main ways in which
organisms interact:
– Competition
– Predation
– Symbiosis
• Mutualism
• Commensalism
• Parasitism
Community Interactions
• Resource availability gives structure to a community.
• Competition occurs when two organisms fight for the
same limited resource.
Types of competition:
• Intraspecific
• Interspecific
Community Interactions
• Predation occurs when one organism
captures and eats another organism.
Predator
Prey
Community Interactions
• Symbiosis is a relationship in which two
species live closely.
• Three types:
– Mutualism
– Commensalism
– Parasitism
Community Interactions
• Mutualism: both organisms benefit
Community Interactions
• Commensalism: one organisms benefits,
the other is unharmed.
Human:
Our eyelashes
are home to tiny
mites
that feast on oil
secretions and
dead skin.
Without harming
us, up to 20
mites may be
living in one
eyelash follicle.
Demodicids
Eyelash mites find all
they need to survive
in the tiny follicles
of eyelashes.
Magnified here 225
times, these
creatures measure
0.4 mm in length and
can be seen only
with a microscope.
Community Interactions
• Parasitism: one organism benefits, the
other is harmed.
Hornworm
caterpillar
The host
hornworm will
eventually die as
its organs are
consumed
by wasp larvae.
Braconid wasp
Braconid larvae
feed on their
host and release
themselves
shortly before
reaching
the pupae stage
of development.
Community Interactions
Endoparasites
Hookworms
•
•
•
Endoparasites
Live in tissue and organs of
organism
Feed on nutrients ingested by host
Examples: tapeworms, protozoan,
hookworms
Extoparasites
Leeches
•
•
•
Extoparasites
Exterior of organism
Feed on host fluids
Example: leeches, fleas, ticks
Population Density And Distribution
• Each population has a density, a
dispersion, and a reproductive strategy.
Population Density And Distribution
• Population density is the number of
individuals that live in a defined area.
– a measurement of the number of individuals
living in a defined space.
• Scientists can calculate population density.
Population Density And Distribution
• Geographic dispersion of a
population shows how
individuals in a population are
spaced.
– Population dispersion refers to
how a population is spread in
an area.
• There are three types of
dispersion:
– Clumped
– Uniform
– Random
Clumped
dispersion
Uniform
dispersion
Random
dispersion
Population Density And Distribution
Clumped
Population Density And Distribution
Uniform
Population Density And Distribution
Random
Population Density And Distribution
• Survivorship curves help to describe the
reproductive strategy of a species.
– Diagram showing the number of surviving members
over time from a measured set of births.
Population Density And Distribution
• Survivorship curves can be type I, II or III
• Type I -low level of infant mortality and an older
population
– Common to large mammals and humans
• Type II -survivorship rate is equal at all stages of
life
– Common to birds and reptiles
• Type III -very high birth rate, very high infant
mortality.
– Common to invertebrates and plants
Population Density And Distribution
Population and Growth Patterns
• Populations grow in predictable patterns
Population and Growth Patterns
• The size of a population is
always changing.
• Four factors affect the size
of a population:
– Immigration:
• organisms coming into a
ecosystem
– Births
– Emigration
• Organisms leaving an
ecosystem
– Deaths
Population and Growth Patterns
• Population growth is based on available
resources.
• There are two types of growth:
– Exponential
– Logistic
Population and Growth Patterns
• Exponential growth is a rapid population
increase due to an abundance of
resources.
Population and Growth Patterns
• Logistic growth is due to a population
facing limited resources.
– Population will level out around carrying
capacity.
Population and Growth Patterns
• Carrying capacity is the maximum number
of individuals in a population that the
environment can support.
• A population crash is a dramatic decline in
the size of a population over a short period
of time.
Population and Growth Patterns
• Ecological factors limit population growth.
• A limiting factor is something that keeps
the size of a population down.
• There are two types of limiting factors:
– Density dependent
– Density Independent
Population and Growth Patterns
• Density dependent limiting factors are affected
by the number of individuals in a given area.
• Examples:
– Predation
– Competition
– Parasitism and
disease
Population and Growth Patterns
• Density independent limiting factors limit a
population’s growth regardless of the density.
• Examples:
– Unusual weather
– Natural disasters
– human activities