Transcript trophic level - El Camino College

Ecology
• the study of _______ interact with each
other and the environment
Energy
• every organism belongs to a trophic level
• trophic level: __________________
• food energy passes through an ecosystem
from one trophic level to another
•food web:
__________
path of
energy
• Food chain:
________path
Members of the food chain
4. producers-consumers
• Producers
– __________________ energy: Autotrophs:
• Plants
• Algae
• some bacteria
– __________ trophic level of any ecosystem
• consumers
– Heterotrophs: obtain their energy by ____________
– Herbivores
• primary consumers, second trophic level
• eat producers
– Carnivores
• secondary consumers, third trophic level
• eat hervibores or other carnivores
– Omnivores
• Eat some carnivores also eat plants
– Decomposers
• break down ________ making them available to other
organisms
• bacteria and fungi
RELATIONS-INTERACTIONS
1. Competition
2. Predator-prey
3. Symbiosis:
1. Parasitism
2. Comensalism
3. Mutualism
4. producers-consumers:
1. Herbivores
2. Carnivores
3. omnivores
1.Competition
• interaction when
_________________________ when
there is not enough of the resource to
satisfy both:
– interspecific competition: different
species
– intraspecific competition: same
species
• principle of competitive
exclusion: Resource
partitioning
– two species competing for
a resource, the species
that uses the resource
more efficiently will
eventually ______the other
locally
– no two species with the
same niche can coexist
– natural selection
favors changes to
________ the
competition and niche
overlap
2. Predator-Prey
• Predation is the consuming of one organism by
another
• essential factor in rich and diverse species
because:
– predators prevent/reduce competition by reducing the
number of individuals of competing species
– predators have large effects on prey populations:
example “10-year cycle” of the snowshoe hare that
appears to be under the influence of food plants and
predators
3.Symbiosis
• interaction of two or more organisms:
whether or not each participant is
unaffected (0), helped (+), or harmed (-)
– Commensalism
– Parasitism
– Mutualism
(+,0)
(+,-)
(+,+)
Levels
1. Niche, organism’s biological role
2. Populations, individuals of the same species living
together
3. Communities, populations of different species that
live together in the same place
4. Ecosystems, a community and the nonliving factors
which it interacts
5. Biomes, plants, animals, and microorganisms living
over wide geographic areas and have distinctive
physical characteristics
6. Biosphere, all the world’s biomes
1. Niche
• organism’s biological role: the sum of all the ways an
organism uses the resources of its environment
(space, food, and many other factors)
The zebras fill a
niche in this African
savanna
community
2. Populations
• Population:
individuals of a
species that live
together:
– Clumped
– Uniform
– random
• Exponential/sigmoid
growth curve:
capacity for growth
• competition and
emigration increase
as a population
approaches its
carrying capacity
3. Communities
• living part or species of an ecosystem
• recognized by their most dominant species
(usually a plant)
4. Ecosystems
• Dynamic and fundamental units of ecology
• have limiting factors that affect diversity:
– Energy
– nutrients
• environmental limiting factors diversity:
– Rainfall
– temperature
TYPES OF ECOSYSTEMS
• Ocean
• Freshwater
• Land Ecosystems
Ocean Ecosystems
• average depth more
than 3 km
• cold and dark,
photosynthetic
organisms confined
to the upper few
hundred meters
• organisms that live
below this level feed
on organic debris
from above
• three main types of ocean ecosystems
1. shallow water
• along the shoreline
• contains the most species
• part of this area
2. open-sea surface
• contains a lot of phytoplankton that drift with the current and
perform 40% of all the photosynthesis that takes place on earth
3. deep-sea water
• Very few organisms live below 300 meters
Freshwater Ecosystems
• include lakes, ponds,
rivers, and wetlands
• large amount of
organic and inorganic
material enters from
nearby land
• Ponds and lakes have
three zones:
– shallow “edge”
– open-water surface
– deep-water, no light
5. Biomes: Land Ecosystems
• seven major and seven minor biomes
• Tropical rain forests:
– richest ecosystems
– Diverse communities
• Savannas:
– grasslands that have widely spaced trees and seasonal
rainfall
– transition between tropical rain forest and desert
• Deserts:
– dry places with sparse vegetation
– Plants and animals may restrict their activity to favorable times of
the year, when water is present
• Grasslands:
– also called prairies
– in temperate areas
– Most have been converted to use by agriculture
• Deciduous forests:
– trees that drop their leaves in the winter
• Taiga:
– coniferous trees
– extends across vast areas of North America and Asia
• Tundra:
– open grassland
– far north beyond the taiga
– Permafrost, or permanent ice, usually exists within
1 meter of the surface
• Chapparal:
– evergreen, often spiny shrubs and low trees
– dry summer climate, also known as Mediterranean
• Polar ice caps
– Arctic Ocean in the north and the Antarctica in the
south
– almost no precipitation and freshwater is scarce
Practice questions
1.The way a species makes its living, that is, the
biological and physical conditions in which it
exists, is called its ________
2.In the levels of ecological organization, the lowest
level, composed of individuals of a single
species who live near each other, share the same
resources, and can potentially interbreed is
called a ___________
4. A major principle of ecology states that “no two
species can occupy exactly the same niche. One
will utilize the resource more efficiently than the
other and will drive the second species to
extinction” This is the principle of __________
5. The following are examples of symbiosis except:
A)Mutualism B)predation C)parasitism D)commensalism
6. Energy from light is converted into chemical
energy for organisms by ________
8. The number of carnivores found at the top of an
ecological pyramid is limited by:
A) number of organisms below
B) number of trophic levels below
C) amount of biomass below
D) amount of energy transferred to the top carnivores
13. When the number of organisms remains more or less the same over
time in the specific place where these organisms live, it is said that
this population of organisms has reached the _____ ____of that
place.
14. All the animals and plants that live in the same location make up a ___
15. For similar species to occupy the same space, their niches must be
different in some way. One way for these species to both survive is ___
____
16. A relationship between two species where one species benefits (+)
and the other is neither hurt nor helped (0) is known as _________
17. Predators can assist in maintaining the species diversity of an area
by:
A) increasing competitive exclusion between prey species
B) decreasing competitive exclusion between prey species
C) not affecting competitive exclusion between prey species