Download Organism

Chapter 23
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Ecology

Environment
- branch of
biology that studies
relationships between
organisms and environment
- factors
that affect an organism
during its lifetime
◦ Biotic factors
 Living things that affect
an organism
◦ Abiotic factors
 Non-living things that
affect an organism

Organism
◦ Smallest living unit

Populations
 Groups of organisms of same species

Communities
 Interacting groups of populations of different
species
 Niche - role in community for each organism

Ecosystem
 All interacting organisms in an area and their
interactions with their abiotic surroundings
Sequence of organisms feeding on one
another

At the bottom of Food Chain: Producers
• Convert sunlight into energy via photosynthesis
– Produce organic material from inorganic
material
•Green plants, algae, some bacteria
Above the Producers will be the
Consumers
 Cannot get energy directly from
sun
 Obtain energy in form of organic
matter
◦ Animals
 Primary consumers
(Herbivores: plant eaters)
 Secondary consumers
(Carnivores: meat eaters)
 Omnivores (eat both plants and
animals)
At the top will be the Decomposers
 Organisms that decompose
dead bodies into CO2, H2O,
ammonia and other inorganic
compounds
 Bacteria, fungi

Trophic level – stage of energy flow through
an ecosystem
◦ Trophic Levels:
• First level: producers (plants)
• Second level: herbivores (eat plants)
• Third level: primary carnivores (eat
herbivores)
• Fourth level: secondary carnivores (eat
primary carnivores)

Two physical laws
◦ 1. Energy can neither be created or destroyed
 Follow energy through tropic levels
◦ 2. Natural processes lead to a disordered state
(entropy)
 As energy passes form one trophic level to another,
there is a reduction in the amount of available
energy in living things and an increase in the
amount of heat in the surroundings
 About a 90% loss in available energy from
one trophic level to another

Biomes: large regional ecosystems that
share similar characteristics:
◦ Temperature
◦ Vegetation
◦ Animals
◦ Terrestrial
◦ Aquatic

1. Tropical Rainforest
◦ Near equator in Central and South
America, Africa, parts of southern Asia
and some Pacific islands
◦ Over 80 (up to 200) inches of rain
◦ Temperature has little fluctuation
◦ Greatest biodiversity in Flora and Fauna
 Flora: balsa, teak, ferns, orchids, vines,
mosses
 Fauna: tree frogs, bats, lizards, snakes,
birds, monkeys, insects
2. Desert
◦ Northern Africa, inland China,
Australia, Antarctica
◦ Less than 10 inches of rain—nothing
to do with temperature!
◦ Huge fluctuation in temperature
◦ Flora: scattered, thorny plants that
lack leaves, i.e. cactus
◦ Fauna: insects, snakes, lizards,
hawks, rabbits

3. Savanna
◦ Central Africa, Northern Australia
and parts of South America
◦ 40 inches of rain during one period
◦ Dry and Rainy Season
◦ Grasses with a few scattered trees
(Acacia)
◦ Antelope, zebra, buffalo, termites,
snakes

4. Temperate Deciduous Forest
◦ Eastern North America, Europe, Japan,
Korea and parts of China
◦ 30-40 inches of rainfall throughout year
◦ Cold winter, hot summer
◦ Deciduous trees – lose their leaves in the
fall
 Maple, oak, hickory, birch, walnut, etc.
◦ Frogs, deer, owls, opossums, skunks, etc.
5. Temperate Grassland
◦ Western North America, Eurasia, Africa,
Australia and South America
◦ 10-30 inches of rainfall
◦ Warm summers—cold winters
◦ Mainly grasses with a few trees along
streams
◦ Prairie dog, antelope grasshopper,
rattlesnake, meadowlark, etc.
6. Chaparral
◦ Mediterranean coast, southern California,
southern tip of Africa, west coast of Chile
and southern Australia
◦ 15 to 40 inches of rain
◦ Wet, cool winters—hot dry summers
◦ Woody shrubs
◦ Reptiles, insects, coyotes, rodents, spiders
7. Temperate Rainforest
◦ Western coastal areas of North America, southern
Chile and west coast of New Zealand
◦ 80 inches of rain
◦ Mild temperatures throughout year
◦ Sitka spruce, Douglas fir, western hemlock,
redwoods, red alder, maple, cottonwood. Mosses,
ferns
◦ Deer, skunks, frogs, opossums, owls, beetles,
mosquitos
8. Boreal Coniferous Forest (Taiga)
◦ Southern Canada, mountains of U.S.,
Northern Europe and Asia
◦ 10-40 inches of rain (lots of snow)
◦ Short, cool, humid summers—long, cold
winters
◦ Small lakes and bogs
◦ Spruce and fir
◦ Bears, mice, wolves, moose, squirrels,
midges, flies
9. Tundra
◦ Extreme northern North America, northern
Europe and Asia (Artic circle)
◦ Less than 10 inches of rain (snow)
◦ Permafrost
◦ Freezing temps most of the year (summer
nights)
◦ Dwarf willow, shrubs, moss, lichen
◦ Caribou, wolves, musk oxen, fox, snowy
owls, mice, insects
Environmental Factors in Aquatic
Ecosystems
•
•
•
•
•
Ability of sunlight to penetrate water
Depth of water
Nature of bottom substrate
Water temperature
Salinity



Marine
◦ High salt content
Freshwater
◦ Low salt content
◦ Standing water (lakes, ponds, reservoirs)
◦ Running water (streams, rivers)
Estuaries
◦ Shallow partially enclosed area where freshwater
enters ocean
◦ Salinity varies with tide and water flow from river
◦ Productive ecosystem
 Sunlight penetrates
 Nutrients collect from river flow


Pelagic - organisms that float or swim in open ocean
◦ Larger, active swimmers
◦ Smaller, weaker swimmers
 Plankton: very small, very weak swimmers, carried by
current
 Phytoplankton
Common in euphotic zone (where sunlight
penetrates)
Carry on photosynthesis (plant like)
 Zooplankton
Feed on phytoplankton (animal like)
Benthic
◦ Organisms that live on bottom
 Seaweed,
 clams,
 crustaceans, etc. (lobsters, shrimps)
 Coral reefs
1. Stationary water (lakes, ponds)
Deep lake
Similar to ocean
Euphotic zone- top
Plankton
Littoral zone- along sides
Rooted vegetation, algae
Limnetic Zone- inner, deeper water
No rooted vegetation
2.
3.
Water running downhill (streams and rivers)
Moving water
 Light reaches bottom
 But most streams not productive
 Major nutrients from terrestrial sources (Leaves,
vegetation, insects)
Estuaries
Freshwater enters the ocean
more salt
tides
Lots of nutrients
Shallow water so light reaches to bottom
Major nursery sites for a number of fish and
crustaceans


Habitat – place or part of an ecosystem
occupied by an organism
Niche – specific functional role of an organism

Predation

Parasitism

Commensalism

Mutualism

Competition
◦ One animal (predator) captures, kills and eats another
(prey)
◦ One organism (parasite) derives nourishment by living
in or on another organism (host)
◦ One organism benefits while the other is not affected
◦ Two species live in close association and both benefit
◦ Interaction between organisms in which both are
harmed to some extent
 Both organisms require a resource in short supply
Environmental resistance- all limiting factors affecting a
population
Carrying capacity - maximum sustainable population of an area
Limiting factors include:
•
•
•
•
•
•
•
Food
Space
Oxygen supply
Climate variations
Disease
Environmental changes
Predators
World population ~ 7 billion
◦ Expected to grow to ~8 billion by 2025
(25% increase
in 20 years)
◦ Divided into two distinct segments:

Developed
2010
1.237 B
2025
1.290 B
Fertility
1.7
Infant m
6/1000
Death
10/1000
% Over 65 17
GNI
$31,200
Less Developed
5.656 B
6.819 B
2.7
50/1000
8/1000
6
$4,760

Almost all earth’s surface affected by humans
◦ More than 80% of land modified

Habitat Destruction
◦ Other species displaced
◦ More resources diverted or destroyed by humans

Global Climate Change (?)
◦ Increased amounts of greenhouse gases (CO2, Methane)


Pollutants (organics, mercury, DDT, etc.)
Consumption of the developed world
◦ Less than 20% of population consumes ~60% of energy
 US has <5% world’s population but consumes ~25% of its energy
◦ Food