A community is an assemblage of interacting species sharing the same environment. Species composition refers to the contribution of each plant species to the vegetation, while species diversity measures both species richness and evenness. Habitat is where a species lives and reproduces, while ecological niche describes a species' role and how it acquires resources. Community interactions include competition between populations for limited resources, predator-prey relationships that can cause populations to fluctuate, and prey defenses against predation such as camouflage, warning signals, and mimicry. Symbiotic relationships between species include parasitism, commensalism, and mutualism.

1. 45.1 Ecology Of Communities

2. Community is an assemblage of populations of different species interacting with one
another in the same environment.
Species Composition
(The contribution of each plant
species to the vegetation )
Species Diversity
(A measurement of species
richness combined with evenness)

3. Coniferous forest
• Squirrel
• Moose
• Snowshoe hare
• Bear
• Red fox
• Wolf
Tropical Rain Forest
• Kinkajou
• Monkey
• Anteater
• Jaguar
• Tapir
• Bat
• Sloth

4. •Habitat and Ecological Niche
Habitat is a particular place where a species live and
reproduces
Ecological Niche is the role a species plays in its community
includes the methods the species uses to acquire the
resources it needs to meet energy, nutrient and survival
demands.
Community Interactions

5. COMPETITION BETWEEN POPULATIONS
oCompetition occurs when members of different species trying to use
a resource that is in limited supply.
oResource partitioning is the division of resources in order to decrease
competition between two species.
oLeads to increased niche specialization and less niche overlap.
oFor example: involves owl and hawk populations. They eat on similar
prey which is small rodents, however owl are mocturnal hunter and
hawks are diurnal hunters. So the niche will became two as a
divergence of behaviour.

6. • Character displacement is the tendency for characteristics to be more
divergent when populations belong to the same community than
when they are isolated.
• Often used as evidence that competition and resources partitioning
have taken place.
• As another example: by considering that swallows, swifts and
martins all eat flying insects and parachuting spiders, these birds
even frequently fly together in mixed flocks.
• However, each type of birds has a different nesting site and migrates
at a slightly different time of year. So they are not competing for the
same food source at the same time.

7. PREY-PREDATOR INTERACTION

8. ❑Predators play a role in determining the population of preys
❑Example:
❑The gardener took prickly-pear cactus to Australia from South-
America, the cactus spread out of control.
❑The cacti were brought under control when a moth from South
America, whose caterpillar feeds only on the cactus , reducing the
cactus population.
❑ Now both cactus and moth are found at greatly reduced densities
in Australia.

10. • Sometimes, instead of remaining in a steady state, predator and
prey populations fluctuated in size.
• We can appreciate that an increase in predator population size
instead of the establishment of a steady population size can also
occur.At least, 2 possibilities account for the reduction;
1.the biotic potential of the predator is so great that its increased
number overconsume the prey, and then as the prey population
declines, so does the predator population.
2. the biotic potential of the predator is unable to keep pace
with prey, and the prey population overshoots the capacity and
suffers a crash . Now the predator population follows suit a lack of
food.

11. PREY DEFENCES

12. CAMOUFLAGE
•ability to blend into
the background
• Help the prey avoid being
detected by the predator.
toad is masterful at blending
into its surroundings.

13. WARNING COLORIZATION
• Tell the predator
that the prey is
potentially
dangeraous
• As the warning to
the predators,
poison arrow frogs
are brightly coloured

14. FRIGHT
• The large false
head of the
South
American
lanternfly may
startle a
potential
predator.
• A large false
head with false
eyes, making it
resemble the
head of an
alligator

15. Porcupine

16. ASSOCIATION
• Association with
other prey is the
command
strategy that
may help avoid
captured.
Herds of
mammals
Flocks of birb
School of fish

17. MIMICRY
The resemblance of one species to
another that possesses an overt
antipredator defense .

18. Batesan Mimic (a mimic that lacks of
defense of the organism it resembles)
• Once an animal
experiences the defense of
the model organism, it
remember the coloration
and avoids all animals that
look similar.
• Example: the insects
( flower fly and longhorn
bettle) that resemble the
yellow jacket wasp, BUT..
THEY DO NOT HAVE STING
WHILE THE YELLOW JACKET
WASP HAVE STING.

19. Example;
VICEROY BUTTERFLY
mimicking MONARCH
BUTTERFLY
SCARLET KINGSNAKE
mimicking VENOMOUS
CORAL SNAKE

20. Mullerian Mimic (Mimics that shared
the same protective defence)
• The bumblebee is the Mullerian
mimic of the yellow jacket wasp,
BECAUSE BOTH OF THEM HAVE
STING.

21. SYMBIOTIC RELATIONSHIPS
• Symbiosis is the close association between two different species
over long periods of time.

22. SPECIES 1 INTERACTION SPECIES 2
PARASITISMBenefits (parasite)
- endoparasite & ectoparasite
Benefits
Benefits
Harmed (host)
No Effect
BenefitsMUTUALISM
COMMENSALISM
*Cleaning symbiosis is a symbiotic relationship in which crustaceans, fish, and birds act as cleaners for a
variety of vertebrates

23. EXAMPLE:
parasitism
-heartworm-
-endoparasite-
commensalism
-shark & remora-
mutualism
-clownfish & sea anemons-