Section 14.1:
Habitat & Niche
Biology
Objectives
1. How does a habitat differ from a niche?
2. How does resource availability give structure to a
community?
3. What is the difference between competitive exclusion
and ecological equivalents?
Species & Their Environment
 In order to understand what an individual, population,
and/or community need ecologists need to study
interactions
 Between species
 Between a species and its environment
Habitat & Niche
 All of the biotic and abiotic factors in the area where an
organism lives
 Includes all aspects of the environment
 Each species interacts with its environment in a
different way
 Ecological niche: all of the physical, chemical, and
biological factors that a species needs to survive, stay
healthy, and reproduce
Habitat & Niche
 Habitat = where a species lives
 Niche = how it lives within that habitat
 Niche Includes:
 Food: type of food, competition for food, where it fits
within the food web
 Abiotic Conditions: Range of temperatures and amount of
water, etc., that a species can tolerate in it environment
 Behavior: Time of day species is active, and when it
reproduces
Habitat & Niche
Lion
Antelope
Habitat = African Plains
Lion
Antelope
Niche
Lion
 Uses the grass for
camouflage
Antelope
 Uses grass for food
 Eats antelope
 Moves primarily during the
day
 Hunts at dawn & dusk
 Travels in herds
 Lives in small groups
 Spends afternoons resting
in shade
Resource Availability
 A species needs food, water, and shelter to be
successful in a habitat
 The organism that is best able to get to these resources
will survive and reproduce
 But, what about competition over limited resources?
Competitive Exclusion
 Many species can share the same habitat and use some of the
same resources
 But, when two species use the same resources in the same way,
there will always be one that is better adapted to the
environment
 Principle of Competitive Exclusion:
 When two species are competing for the same resources, one
species will be better suited to the niche than the other
 This leads to one species being pushed out of the niche or it
becomes extinct
Competitive Exclusion
 Can result in three possible outcomes
 Extinction
 Niche Partitioning
 Evolutionary Response
 Extinction:
 Due to competition for the same resources, the population
of one species will slowly decline until it no longer exists
Competitive Exclusion
 Can result in three possible outcomes
 Extinction
 Niche Partitioning
 Evolutionary Response
 Niche Partitioning:
 Naturally dividing different resources based on competitive
advantage
 Could lead to eating the same type of food, but locating it in
different places
Competitive Exclusion
 Can result in three possible outcomes
 Extinction
 Niche Partitioning
 Evolutionary Response
 Evolutionary Response:
 Divergent evolution: competition for resources led to the
development of different traits that helped to solve the
problem of competition
 One animal develops larger teeth to help the species adjust, so
that it does not die out, but begins to eat different food
 This decreases the competition for resources
Ecological Equivalents
 Competitive exclusion occurs when species are
competing for resources within the same community
 In different communities, ecological equivalents occupy
similar niches
 Ecological Equivalents: species that occupy similar
niches, but live in different geographical regions
 Because these species live in different regions, they
never compete for the same resources
Output
 Give the definition of competitive exclusion in your own
words. Provide an example, giving the three possible
outcomes for your example species.
 A bison and an elk live in the same habitat and feed on
the same grasses. Does this mean that the competitive
exclusion principle does not apply? Explain why or why
not.
 Considering the competitive exclusion principle, why
may it be harmful to transport a species, such as a
rabbit, to another habitat where it currently does not
exist?