Transcript Interactions in Ecosystems - Salisbury Composite High School

Ecosystems and
Populations
Terms
 Ecology: study of
how organisms
interact with each
other and their
non-living
environment
(biotic-living and
abiotic-non living
factors)
 Ecosystem: The biotic community
and all abiotic factors.
 Community: All the living
organisms/populations in an area
 Population: group of organisms of
same species
Roles in Ecosystems
 Habitat: the area
where an organism
lives; its address
(eg. Tropical
rainforest);
 Niche: an
organism’s
profession; what it
eats, what eats it,
the habitat, time
when active, etc.
Competition
 Having differing niches
allows organisms to
reduce competition
 Eg. Hawks vs. owls
Competition
Warblers Yellow rumped –
only in bottoms
of trees
Blackburnian –
only at tops of
trees
Biodiversity
 describes the number and variety of
organisms in an ecosystem.
 Greater biodiversity means more stability
because if one species in a food web is
lost, its predator can switch to another
prey.
Indicator Species
 are species of organisms that provide an
early warning that an ecosystem is being
affected by some factor.
 Usually, these species are very sensitive
to changes in an ecosystem, or to specific
changes of ecosystem conditions.
Exotic Species
 Second only to
habitat loss as
a cause of
extinction
 New species
occupy niches
of natural
populations and
out compete
them
purple loosestrife
zebra mussels
starlings
Species At Risk
Less
severe
risk
Most
severe
risk
Special concern – numbers are
declining at the range / fringe of the
area
Threatened – species may become
endangered if threatening conditions
are not reversed
Extirpated – a species no longer
exists in one particular area, but is
still found in other areas
Endangered – a species is close to
extinction in all parts of their natural
habitat
Extinct – a species no longer exists
Extinct Canadian Species
Great Auk -1844
Sea Mink-1870
Labrador duck-1875
Genetically Modified
Crops
 Transfer of genes
from one organism to
another unrelated
organism
 Eg. Roundup
resistance to canola
 Fish antifreeze
proteins to
strawberries
 Vitamin A gene
to rice
 Green Fluorescent
Protein to
monkeys/pigs
Biological Control
 Using a natural predator to control an
unwanted species.
Population Line Graphs
 typically
have
numbers on
vertical axis
and time on
horizontal
axis
Biotic Potential
 the maximum
number of
offspring that the
species could
produce with
unlimited
resources
Environmental Resistance
 Is the limiting factors
on a population
 Include food, shelter,
water, predation, etc.
 Puts brakes on biotic
potential (B) –
maximum
reproductive rate
Logistic Growth
S shaped
curves are
typical of
stable
populations
with a
constant
food source
Logistic Growth
 Eg. Wild
Horses on
reserve land
in AB
Exponential Growth
 J shaped curve (initially) occurs with
short-lived populations that rapidly
deplete their environment
Exponential Growth
 Eg. Flies on a carcass
Carrying Capacity
 Is the number of
organisms a
habitat can
sustain over the
long term
 “k”
Overshoots
 Result when k is
greatly exceeded
and the
environment
deteriorates
Limiting Factors to
Populations
 Shelford’s Law of
Tolerance: an
organism can
survive within a
certain range of
any abiotic factor
 Greater the range,
the greater the
ability for the
species to survive
Limiting Factors on
Populations
 Law of the Minimum: if any one of many
needed nutrients/limiting factors is
reduced below the required levels, the
population growth rate declines
Limiting Factors
 Can be density independent – those that
will affect a population regardless of its
size
 Eg. Cold winter
 Lack of water
Limiting Factors
 Can be density dependant – those that
increase when the population size
increases
 Eg. Disease
 Predation
 Food Supply
Human Population Growth
Approximately 6.6
billion
Taxonomy - naming

Naming system to identify different
species

Used binomial nomenclature – two
words
Taxonomy


First word is the genus
Second is the species
Equus caballus
Equus burchellii
Taxonomy
Castor canadensis
Ursus maritimus
Species - Definition

A species is a group of organisms that can
interbreed under natural conditions and
produce fertile offspring
Levels of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
(Kings play chess on fine grain sand)
Classification
Giraffe
Horse
Pig
Kingdom
Animalia
Animalia
Animalia
Phylum
Chordata
Chordata
Chordata
Class
Mammalia
Mammalia
Mammalia
Order
Artiodactyla
Perissodactyla
Artiodactyla
Family
Giraffidae
Equidae
Suidae
Genus
Giraffa
Equus
Sus
Species
camelopardalis
caballus
scrofa
The Kingdoms
5 of them:
1.
Monera: Bacteria and
blue-green algae
- sometimes subdivided
into eubacteria and
archaebacteria
- prokaryotic (very simple)
cells
2.
-
-
Protista – mostly
single celled
Eukaryotic (true
nucleus)
Usually aquatic
3.
-
Fungi – most
multicellular
Heterotrophic,
chitin cell walls
4. Plantae:
multicellular,
autotrophs
5. Animalia:
multicellular,
heterotrophs