Transcript PPT

Principles of Biology
By
Frank H. Osborne, Ph. D.
Ecology
Definition of Ecology
Ecology is the science that deals in the
interrelationships between organisms and
their environment. The environment contains
physical factors and living factors.
Physical Factors
The physical environment consists of the soil
and rocks in the surroundings of the
organism. The light, heat and water in the
surroundings are also part of the physical
environment.
Living Factors
The living environment consists of all
plants and animals nearby which
interact with the organism. This is
a community. All of the organisms of the
same species within the community constitute
a population.
Energy in the Environment
Path of Energy: Sun  Plant  Insect  Frog  Snake
Food Chains
•All energy on the surface of the Earth is derived
from the Sun. Photosynthesis occurs in the
primary producers that are green plants.
•Primary consumers eat the plants.
•Predators eat the primary consumers. The
predators are secondary consumers.
•This constitutes a food chain.
Food Chains
•There may be tertiary or quaternary
consumers.
•In North America, most food chains end with
a predatory bird, such as the eagle.
Flow of Energy in Food Chains
•Energy in food chains always begins with the
Sun. Sunlight is absorbed by green plants.
The green plant uses photosynthesis to trap
solar energy and convert it to glucose. The
glucose molecule contains stored chemical
energy.
Flow of Energy in Food Chains
•The primary consumer eats the green plant
and gains some of the energy from it. The
primary consumer is a herbivore because it
eats plants. Most of the energy of the plant is
lost when it is eaten.
Flow of Energy in Food Chains
•The secondary consumer eats the primary
consumer. It is a carnivore. The carnivore
obtains some of the energy stored in the
animal it eats but most of the stored energy is
lost.
Flow of Energy in Food Chains
•Thus, energy is lost as the food chain grows
longer. In order to obtain the maximum
amount of energy stored by the original
producer plant, you have to eat the plant
directly.
Flow of Energy in Food Chains
•Organisms die eventually. Their remains are
recycled and returned to the environment by
decay organisms, particularly bacteria and
fungi that derive energy from dead organic
material.
Food Webs
•Food webs are more complicated than food
chains because some consumers may be eaten
by several predators. This causes branches in
food chains.
Succession of Plants (1)
•Newly exposed rock
will first be colonized
by lichens.
Succession of Plants (2)
•These are joined by
small plants like
mosses and liverworts.
After some soil begins
to form, ferns and
grasses move in.
Succession of Plants (3)
•More soil forms
and then shrubs and
pine trees begin to
grow. The thickness
of the soil continues
to increase.
Succession of Plants (4)
•The shrubs and pine
trees are replaced by
oak trees, beech trees
and finally maple trees.
In the temperate forests
of the United States, the
climax vegetation will
be maple trees.
Succession of Plants (5)
•The sequence from
bare rock to mature
forest takes about 100
years.
Ecological Succession
•Early (pioneer) plants
- 1. lichens
- 2. liverworts/mosses
- 3. ferns
- 4. grasses
•Intermediate plants
- 5. pine trees
- 6. oak trees
- 7. beech trees
•Climax forest plants- 8. maple trees
Biomes
•A biome is a collection of many communities
which is characterized by the same
form of climax vegetation.
•The climax vegetation is a botanical community.
For example, the northeastern United States is in
the biome known as the Temperate Deciduous
Forest. "Deciduous" means that the leaves fall
off the trees in the autumn.
Biomes
•Terrestrial biomes depend on climate. The
climate changes as you travel toward the North
Pole. It changes in a similar fashion as you go
high up into the mountains. Climates similar to
Tundra and Taiga are found on high mountains.
Biomes
There are six generally recognized terrestrial
biomes, distinguished by their climate and
climax vegetation.
• Tundra
– very cold, short growing season, ground is
permanently frozen (permafrost)
• Taiga
– cold, moderate growing season, predominant plants
are trees with needles and cones
Biomes
• Temperate Deciduous Forest
– moderate climate, long growing season, trees have
broad leaves which fall off during autumn
• Grassland
– moderate climate but too dry to support trees. Best
for growing wheat and corn
Biomes
• Desert
– very dry with extremes of hot and cold.
Predominant vegetation is cactus and other plants
adapted to very dry conditions
• Tropical Rain Forest
– very humid all the time--supports lush vegetation
Biomes
•The marine biome includes all of the
communities that are found in the ocean. The
types of living things present in a given part of
the marine biome depend on the water
temperature, availability of food and nutrients
for the sea life, and other factors.
Material Cycles
•Nature works in cycles. There are a number of
cycles in the ecosystem that serve to regenerate
and renew materials for use by living things.
Carbon-Hydrogen-Oxygen Cycle
•Photosynthesis by green plants releases oxygen
into the atmosphere because oxygen is the waste
product of photosynthesis.
•Living things use oxygen for their respiration
and release water and carbon dioxide into the
atmosphere. These materials are then used by
the plants for more photosynthesis.
The CHO Cycle
The Nitrogen Cycle
•Nitrates from the soil are absorbed by the green
plants and are used to make plant proteins.
Animals make proteins from amino acids
derived from plant proteins.
•Dead plant and animal tissue is decomposed by
bacterial action. Other bacteria in the soil
transform nitrogen products to reduce more soil
nitrates for plants.
The Nitrogen Cycle
Relationships Between Organisms
•Between organisms of the same species there
can be sexual contact, cooperation and social
organization.
•Between different species, the interactions are
commensalism, mutualism, parasitism and
predation. All of these interactions are forms of
symbiosis.
Symbiosis
•"Symbiosis" means living together. The term
does not indicate the nature of the relationship.
•Life scientists prefer to use one of the other
terms that give a more precise indication of the
relationship.
Commensalism
•Commensalism is where one organism benefits
but does not cause any harm to the other. An
example is Spanish Moss. It hangs from trees in
Florida. It is not a parasite; all it needs is a place
to hang. It gets its water from the air.
Mutualism
•In mutualism, a mutually beneficial relationship
exists where both partners benefit. An example
is the relationship between the legumes (beans,
peas, clover, alfalfa) and the nitrogen-fixing
bacteria. The bacteria produce usable nitrogen
for the plant and the plant gives them a place to
live.
Mutualism
•Termites eat wood which they cannot digest.
There are bacteria and protozoa in their
digestive systems that can digest cellulose to
produce glucose. The microorganisms benefit
because they have a place to live and a constant
supply of cellulose to digest. The termites get the
benefit from the glucose released from the
cellulose by the bacteria and protozoa.
Mutualism
•A cow eats grass that it cannot digest. In the
multichambered stomach of the cow are bacteria
and protozoa that digest the cellulose for the
cow. In return they get a place to live and a food
supply.
Parasitism
•In parasitism, the parasite benefits but the host
does not. Parasites are generally internal. In the
lower phyla of the animal kingdom, most groups
contain one or more parasites of various kinds.
Parasites require the host for reproduction.
Predation
• A predator is free-living and feeds on other
organisms. Some, like lions, kill and eat an
entire organism. Others, like mosquitoes, take
only a small part.
The End
Principles of Biology
Ecology