Transcript Population Distribution

Unit 6
Populations Dynamics
Define these 26 terms:
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Commensalism
Habitat
Herbivory
Mutualism
Niche
Parasitism
Predator
Prey
Resource
Partitioning
• Symbiosis
• Age structure
• Population
density
• Population
distribution
• Population size
• Sex ratio
• Carrying
capacity
• Emigration
• Immigration
• Migration
• Age structure
diagram
• Population
• Biotic
potential
• Density
dependent
factor
• Survivorship
curve
• Invasive
species
• Succession
Population Dynamics
Species Interactions
Unit 6A
Chp. 5.2
REVIEW
Ecosystems:
Everything is Connected
What is an ecosystem?
An ecosystem includes all
the different organisms
living in a certain area,
along with their physical
environment
Two parts of an ecosystem:
Biotic Factors:
The living parts of an ecosystem
which interact with each other
and the nonliving parts
Abiotic Factors:
The nonliving parts of the
ecosystem
Hierarchy
• Biosphere
• Ecosystem
• Community
• Population
• Species
• Organism
Niche v.s. Habitat………
• Niche:
• all of the organism’s
relationships with its
environment (both living and
nonliving), a way of life
• Examples: what it eats, what
its parasites are, rotting when
it dies, when & how it
reproduces, biorhythms, …
• Habitat:
• The actual place an organism
lives
• Examples: rain forest,
freshwater pond, coral
reef,…
Tolerance & Competition
• Tolerance – ability to survive
and reproduce under changing
environmental conditions
– Specialists – very restricted
tolerance ranges
• Competition – when multiple
organisms seek the same
limited resources
Competitive Exclusion
• When a competitor species is
very effective and excludes
another species from the
resource use entirely.
– Example: the invasive
species zebra mussels
outcompeted 20 native
mussels in Lake St. Clair by
1997.
Resource Partitioning
• When competing species
partition or divide the
resource they use in
common by specializing in
different ways
• Ex. – birds specialize by
particular types of insects &
parts of the tree ; can lead
to evolution - Galapagos Is.
SYMBIOSIS
A long-term and
physically close
relationship between
two organisms from
different species in
which at least one
organism benefits.
Ways species interact
with each other:
• Predation
• Competition
• Parasitism
• Mutualism
• Commensalism
Predation
1. Predation – one organism
kills and eats another
organism
2. Prey – the organism that
is eaten
3. Predator – the organism
that does the eating
4. Example: lynx and hare
Competition:
A relationship between
species in which they
attempt to use the
same limited resource
Can be direct or indirect
Parasitism
1. Parasite – organisms that live
in or on another organism and
feed on it without immediately
killing it
2. Host – the organism the
parasite takes its nourishment
from
3. Parasitism – the relationship
between parasite & its host
Mutualism
• A cooperative
partnership between
two species
• Both benefit
• Examples?
• Barn cat and farmer
• Sea Anemone and
Anemonefish
Commensalism
• A relationship in which
one species benefits
and the other is
neither harmed nor
helped
• Example?
• Bromeliad and tree
• Shark and ramoras
Herbivory
• The interaction when an animal
feeds on a plant
• Most common type: insects
• In most cases, herbivory does
not kill a plant directly but it may
affect its growth and
reproduction
• Plant defenses: toxic chemicals,
thorns, spines, irritating hairs,
hormones that stimulate growth
Unit 6A (5.2) Review
1. Explain how competition can affect an
organism’s niche.
2. How are predation, parasitism, &
herbivory similar? Different?
3. Human digestive tract is filled with
bacteria that get nutrients by helping
digest food. Is this symbiotic?
Mutualism or commensalism? Explain.
• When finished with this small group
work, quietly work on your vocabulary
Population Dynamics
Unit 6B
Describing Populations
Chp. 4.2
Population Size
• The # of individual organisms
present in a given population at
a given time
• May increase, decrease,
undergo cyclical change or
remain the same over time
(healthy pop.)
• If a population declines rapidly,
it can mean extinction is coming
(ex. Passenger pigeon)
Determining Population Size
• In almost all cases, population
size is estimated using sampling
techniques.
– Ecologists count the # in a
smaller sample area, then
estimate the # in the larger
overall area
– Sometimes it is easier to find
signs of organisms instead of
the organisms themselves
Population Density
• # of individuals within a
population per unit area
• Higher population
densities make it easier
to find mates or group
together, however
crowding leads to
parasites and
competition
Population Distribution
• Describes how organisms are
arranged within an area
• Random distribution – individuals
arranged in no particular pattern
• Uniform distribution – organisms
are spread evenly in an area
• Clumped distribution – individuals
arrange themselves based on
availability of resources
Age Structure & Sex Ratios
• # of organisms of each
age within a population
• Age structure diagrams –
tools scientists use to
show the age structure
of populations
• Sex ratio – proportion of
males to females
4.2 Review
• How is a population’s size related to its
well-being?
• Which population of flamingos is more
dense: 15 flamingos in a 5-square-meter
area, or 40 flamingos in a 10-squaremeter area?
• Describe the 3 patterns of population
distribution. Which of these is the most
common distribution in nature?
• 4.2 review packet
Population Dynamics
Unit 6C
Population Growth
Chp. 4.3
Factors that determine
Population Growth
• Births, deaths, immigration,
emigration
• Natality – rate of birth
• Mortality – rate of death
• Survivorship curve – shows
how likelihood of death
varies with age, Types I, II,
& III
• Type I – individuals are
most likely to die when
they are old
• Type II – mortality
remains constant
throughout an individual’s
lifetime
• Type III – mortality is
highest for young
members of the population
Migration
• Seasonal movement into or
out of an area
• Immigration – arrival of
individuals from outside a
given area
• Emigration – departure of
individuals from a given area
• Births & immigrations add
individuals to a population;
deaths & emigrations subtract
Calculating Population Growth
individuals added – individuals subtracted
• Tells us net change in population size
• Ex. – annual birthrate = 18/1000, annual
death rate = 10/1000, annual
immigration rate = 5/1000, annual
emigration rate = 7/1000. Calculate
annual growth rate
• (18 + 5) – (10 + 7) = 6
• Usually expressed as a percent
• (6/1000) x 100% = 0.006 x 100% = 0.6%
How Populations Grow
• Exponential Growth – when a
population increases by a fixed
% each year, J curve
• Logistic Growth – describes how a
population’s exponential growth is
slowed and finally stopped by
limiting factors which determine
its ultimate carrying capacity
• In nature, usually populations
fluctuate or rise & crash
Limiting Factors
• Density-dependent factors –
high population density increase
competition for resources;
ex. – predation, disease, food
& water
• Density-independent factors –
limiting factors whose influence
is not affected by pop. density;
ex. – floods, fires, landslides,
climate change
Biotic Potential
• The maximum ability of an
organism to produce
offspring in ideal conditions
• Influenced by gestation
time (embryo to birth) and
generation time (birth to
sexual maturity), as well as
# of offspring born at a
time
4.3 Review
• A population has a birthrate of 10/1000, a
death rate of 9/1000, an immigration rate of
3/1000, and an emigration rate of 7/1000.
What is its growth rate? Is the population
getting larger or smaller?
• What is the difference between exponential
growth & logistic growth? Which is more
common over long terms in nature?
• In your own words, define limiting factor
and biotic potential.
• 4.3 review packet
Population Dynamics
Unit 6D
Community Stability
Chp. 5.4
Ecological Succession
• Somewhat predictable series of
changes over time experienced
by a community
• Primary succession – when a
disturbance is so severe, no
vegetation or soil life remains
• Secondary succession – begins
when a disturbance dramatically
alters an existing community but
does not destroy all living things
• Pioneer species – colonize newly
exposed land first in primary
succession; ex. – lichen take
firm hold on rock, capture
moisture, release acids, soil
begins to form
• Climax community – a stable
community that “completes”
the succession process;
ex. – beech-maple forests,
old growth forests
Invasive Species
• Non-native organisms that spread
widely in a community because
they lack limiting factors
• Not all exotic species become
invasive as some stay small &
localized
• Not all invasive species are bad,
ex. – European honeybee
• Bad ex’s – zebra mussels, cane
toad, kudzu vine
5.4 Review
• Explain how disturbances can throw a
community out of a balanced state and into a
period of adjustment.
• List examples of primary & secondary
succession and describe the stages; identify
the factors that determine the type of
succession that will occur.
• Identify a pioneer species & list several
examples in different ecosystems.
• Describe the how, when, where of climax
communities.
• List examples of invasive species in Florida.