Transcript ECOLOGY - Bishop Amat Memorial High School

ECOLOGY
ECOLOGY examines…
1.
2.
3.
4.
Distribution of organisms
Frequency of organisms
Interactions between
organisms (biotic influences)
Interactions between
organisms and environment
(abiotic influences)
Levels of Ecological Study:
Organismal
Ecology
Population Ecology
Community Ecology
Ecosystem Ecology
Important Terms
Species
 a group of organisms which can interbreed
and produce fertile offspring
Population
 a group of organisms of the same species
who live in the same area at the same time
Community
 a group of populations living and interacting
with each other in an area
Ecosystem
 a community, along with the ways in which
all of the organisms interact with each
other and the ways they interact with their
abiotic environment
The Biosphere

Entire portion of Earth inhabited by life



Atmosphere up to an altitude of several km
Land down to and including water-bearing rocks 3km below
ground
Lakes, streams, caves and oceans down to a depth of several
km
The biosphere consists of
all the world’s
ecosystems, which are
interdependent and
interrelated
Ecosystems function together in
the biosphere

Ecosystems are rarely isolated
because organisms can move
back and forth between them
Examples of organisms moving
between ecosystems
 Swallows
spend winter in Africa
and summer in Europe
Examples of organisms moving
between ecosystems
 Blackpoll
warbler breeds in
northern U.S. and in Canada, but
migrates to South America for
winter
Examples of organisms moving
between ecosystems
 Amphibians
and several insects have
larval stages in water, but as adults are
on land or in the air
Result of organisms moving
between ecosystems
 Since
the organisms feed and die,
energy and nutrients move between
ecosystems.
Divisions of
Biosphere
BIOMES
Tropical Rain Forests
Deserts
Savannas
Taigas
Grasslands
Tundras
Deciduous Forests
Aquatic (fresh H2O/marine)
http://earthobserv
atory.nasa.gov/La
boratory/Biome/
Population Ecology
Pertains
to the number and
age groups of particular
species found in a specific
area, using the same
resources.
Offers explanations as to why
the above changes over time.
Population Size, Density, and
Dispersion
Size (N):
total number of individuals in the
population
Density:
number of individuals per unit of
habitat area at a given time
Dispersion:
Pattern of spacing among
individuals w/in geographic
boundaries of population
Dispersion Types:
Random
Uniform
Clumped (aka Aggregated)
Population Density as
described by Age Structure
What is Age Structure?
no. of individuals @ each age
What does AS tell about PD?
Large portion of
the population
is young…
RAPID
POPULATION
GROWTH
Large number of
old, small
number of
young …
DECLINING
POPULATION
GROWTH
Equal numbers
of old and
young …
ZERO
POPULATION
GROWTH
Population Density as described
by Survivorship Curves
Survivorship Curves:
measure the mortality rates of
individuals w/in a population
Type I Survivorship Curve:
Species where most individuals
survive to middle age.
After middle age, mortality
increases
Type II Survivorship Curve
Random survival length for
individuals in population.
Death is likely at any age.
Type III Survivorship Curve
Most individuals die young.
Few survive to reproduce.
Measuring Change in
Populations
Critical Factors:
Natality *
Mortality *
Immigrants
Emigrants
Population Growth Equation:
N
T = B-D
N
T
= bN - dN
Growth Rate Equation:
r = b-d
N
r = reproductive (growth) rate
Biotic Potential
maximum rate at which a
population could increase
under ideal conditions. (rmax)
Aka : Intrinsic Rate of Growth
What affects Biotic Potential?
Age at reproductive maturity
No. of offspring @ each
reproductive event
Frequency of reproduction
Reproductive lifetime
Survival of offspring to repro. age
Biotic Potential cont’d.
Limiting Factors:
those conditions that prevent a
population from attaining its
biotic potential
May be density dependent or
density
independent
Limiting Factors
Density
Dependent
Limiting effect
becomes more
intense as
population density
increases
Predation
Disease
Competition
(intraspecific &
interspecific)
Density
Independent
Occur independent
of population
density
Natural Disasters
Extreme Climates
Carrying Capacity (K)
Maximum no. of individuals of a
population that can be
maintained for an indefinite
period of time by a particular
environment
-
Population Growth Patterns
A.
Exponential Growth:
occurs whenever r > 0
Exponential Growth Curve
B.
Logistic Growth:
occurs when limiting factors
restrict size of population to
the carrying capacity
Growth slows as K is
reached.
Logistic Growth Curve
How does Logistic Growth
influence reproductive rate (r) ?
Equation.
When N is low, K-N
K
is large and :. r is only
slightly changed from rmax
When N is large and when
resources are limited,
K–N
K
Is small and :. Significantly
lower than rmax
So what does this all mean?
Some species populations are
naturally
“r - selected”
Ex: insects, weeds
Some species populations are
naturally
“K – selected”
Ex: humans