Presenting and understanding the concepts of Community Ecology with importance to species interactions, Ecological Niches, character Displacement etc.

1. BY
SURABHI TANWAR
Masters Student in the
Environmental Sciences
Institute of Science, Mumbai
COMMUNITY ECOLOGY

2. What is a Community?
 It is an assemblage of species living close enough
together for potential interaction.
 Communities differ
in their species
richness, the
number of species
they contain, and
the relative
abundance of
different species.

3. FOUR main kinds of species interactions; all play
a role in the formation of community structure...
Competition (-,-)
Predation, parasitism (+,-)
Mutualism (+,+)
Commensalism (+,0)

4.  Competition.
◦ Interspecies competition: can occur
when resources are limited.

5.  Competition.
◦ Interspecies competition for
resources can occur when
resources are in short supply.
 There is potential for
competition between any
two species that need the
same limited resource.
◦ The competitive exclusion
principle: two species with
similar needs for same limiting
resources cannot coexist in the
same place.
G. F. Gause (1934) tested competitive
exclusion principle

6. Ecological Niches
 The total of a species’ use of biotic and abiotic
resources is called the species’ ecological
niche
 Ecologically similar species can coexist in a
community if there are one or more significant
differences in their niches
 As a result of competition, a species’
fundamental niche may differ from its realized
niche

7. Fundamental Niche vs Realized Niche
Fundamental Niche: the niche that a species potentially
could occupy, in the absence of competitors.
Realized Niche: the niche to which a species is restricted
in the presence of competitors.

8.  Classic experiments confirm this.
Fig. 53.2

9. Resource Partitioning
 Resource partitioning is differentiation of ecological niches,
enabling similar species to coexist in a community

10. Character displacement
Body
evolves as
a result of
resource
partitioning
.

11.  Predation.
◦ A predator eats prey.
◦ Herbivory, in which animals eat plants.
◦ In parasitism, predators live on/in a host and
depend on the host for nutrition.

12.  Offset oscillations in the population
sizes of the predator and prey
 Coevolution of predator and prey

13. ◦ Plant defenses against herbivores include
chemical compounds that are toxic.
◦ Animal defenses against predators.
 Behavioral defenses include fleeing, hiding, self-
defense, noises, and mobbing.
 Camouflage includes cryptic coloration,
deceptive markings.
Fig. 53.5Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

14.  Mechanical defenses include spines.
 Chemical defenses include odors and toxins
 Aposematic coloration is indicated by warning colors,
and is sometimes associated with other defenses
(toxins).
Devil scorpionfish
backside

15.  In Batesian mimicry, a palatable or harmless
species mimics an unpalatable or harmful model
monarch viceroy

16. Cuckoo bee
Yellow jacket

17.  In parasitism, one organism, the
parasite, derives nourishment from
another organism, its host, which is
harmed in the process
 Parasitism exerts substantial influence on
populations and the structure of
communities
Mutualism is where two species benefit
from their interaction.
Coral polyp & zooxanthellae
Commensalism is where one species
benefits from the interaction, but other is
not affected.

19. REFRENCES
http://www.bio.miami.edu/ecosummer/lectures/lec_coevolution.html
https://en.wikipedia.org/wiki/Ecological_niche
http://faculty.virginia.edu/bio202/lectures/LectureK7.pdf
http://ani_mardiastuti.staff.ipb.ac.id/files/2011/11/Biopop09_Resource-
Partition.pdf