Terrestrial biomesEcology
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Ecology
The scientific study of the interactions between organisms and the
environment.
It is these interactions that determine the distribution of
organisms across an area as well as their abundance in that
area
Distribution and abundance of the red kangaroo in Australia
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Think about it...
If a fox eats a rabbit (predator-prey relationship) then the gene
pool of that rabbit population is altered by the loss of that
rabbits alleles (microevolution)
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animals
plants
Both biotic and abiotic factors help determine the distribution and
abundance of a species
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Ecosystems
Communities
Populations
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Does an organisms environment play a part?
Of course it does!
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temperature: always warm
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precipitation: almost
characteristics: sparse vegetation & animals, cacti,
succulents, drought tolerant, reptiles, insects, rodents,
birds
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Temperate Grassland
temperature: cold winters/hot summers
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temperature: moderate warm summer/cool winter
characteristics: many mammals, insects, birds, etc.; deciduous
trees; fertile soils
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temperature: cool year round
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Arctic Tundra
precipitation: dry
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Alpine Tundra
precipitation: dry
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Population Ecology
Chapter 52
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Changes to
population size
birth
death
immigration
emigration
ex. introduced to a new environment
African elephant
coming back from near extinction
The J–shaped curve of exponential growth is characteristic of some
populations that are introduced into a new or unfilled environment
or whose numbers have been drastically reduced by a catastrophic
event and are rebounding. The graph illustrates the exponential
population growth that occurred in the population of elephants in
Kruger National Park, South Africa, after they were protected from
hunting. After approximately 60 years of exponential growth, the
large number of elephants had caused enough damage to the park
vegetation that a collapse in the elephant food supply was likely,
leading to an end to population growth through starvation. To
protect other species and the park ecosystem before that happened,
park managers began limiting the elephant population by using birth
control and exporting elephants to other countries.
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Carrying capacity
of course NOT!
what sets limit?
resources, predators, parasites
Carrying Capacity (K)
not fixed; varies with
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K-strategy
have few offspring & invest a lot of energy in raising them to
reproductive age
primates
coconut
r-strategy
insects
Relative number of individuals of each age
What do the data imply about population growth in these
countries?
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Human population
1650500 million
20056 billion
Is the human
population reaching
carrying capacity?
The population doubled to 1 billion within the next two centuries,
doubled again to 2 billion between 1850 and 1930, and doubled still
again by 1975 to more than 4 billion. The global population now
numbers over 6 billion people and is increasing by about 73 million
each year. The population grows by approximately 201,000 people
each day, the equivalent of adding a city the size of Amarillo,
Texas, or Madison, Wisconsin. Every week the population increases
by the size of San Antonio, Milwaukee, or Indianapolis. It takes
only four years for world population growth to add the equivalent
of another United States. Population ecologists predict a
population of 7.3–8.4 billion people on Earth by the year
2025.
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Community Ecology
Chapter 53
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Inter-species interactions
Symbiotic interactions
compete for limited resource
2 species cannot coexist in a community if their niches are
identical
predation / parasitism (-/+)
habitat = address, niche = job
Resource partitioning
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Niche & competition
Competitive Exclusion
No two similar species can occupy the same niche at the same
time
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length of food chain limited by inefficiency of energy
transfer
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Energy transfer
Energy in
Energy through
food chain
how much energy is turned into biomass
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Food webs
Who eats whom?
a species may weave into web at more than 1 trophic level
bears
What limits the length of a food chain?
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Dynamics of energy through ecosystems have important implications
for human populations
what food would be more ecologically sound?
We consume more than just food: water, energy, space/habitat
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change due to disturbances
not all are negative
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Ecological cycle
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Ecological succession
transition in species composition over ecological time
years or decades
Mt. St. Helens
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fertility & depth of soil
The species mix of climax forest is dependent on the abiotic
factors of the region
birch, beech, maple, hemlock
in a certain area
Ecology provides a scientific context for evaluating
environmental issues
warned that use of
pesticides such as DDT
Everything must go somewhere
Nature knows best
Laws of Unintended Consequences
PCBs in sediment
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Ozone Depletion
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genetic diversity within population
loss of genetic diversity
non-native species
lack of competitors & predators
1968
1978
