Download Community Ecology

Lecture Ecology
0011 0010 1010 1101 0001 0100 1011
1
2
• Chapter 53 ~
Community Ecology
4
Community structure
0011 0010 1010 1101 0001 0100 1011
• Community~ an assemblage of
populations living close enough together for
potential interaction
• Richness (number of species) &
abundance…….
• Species diversity
• Community Structure
Hypotheses:
•Individualistic~
chance assemblage with similar abiotic
requirements (most communities)
•Interactive/Organismic~
assemblage based on interaction of its
members acting like a ‘superorganism’
1
2
4
Interactions
0011 0010 1010 1101 0001 0100 1011
• Interspecific (interactions
between populations of different
species within a community):
•Predation
including parasitism; may
involve a keystone
species/predator
•Competition
•Commensalism
•Mutualism
1
2
4
Predation defense
• Cryptic (camouflage) coloration
0010 1010 1101
0001 0100
1011
•0011
Aposematic
(warning)
coloration
• Mimicry~ superficial resemblance to
another species
√ Batesian~ palatable/ harmless species
mimics an unpalatable/ harmful model
√ Mullerian~ 2 or more unpalatable,
aposematically colored species resemble each
other
1
2
4
Competition: a closer look
0011 0010 1010 1101 0001 0100 1011
• Interference~ actual fighting
over resources
• Exploitative~ consumption
or use of similar resources
• Competitive Exclusion
Principle (Lotka / Volterra)~ 2
species with similar needs for the
same limiting resources cannot
coexist in the same place
√Gause experiment
1
2
4
Competition evidence
0011 0010
1010 1101
0001 0100 1011
• Resource
partitioning
~
sympatric species consume slightly
different foods or use other
resources in slightly different ways
• Character displacement~
sympatric species tend to diverge in
those characteristics that overlap
1
Ex: Anolis lizard sp. perching sites in the
Dominican Republic
2
4
Ex: Darwin’s finch beak size on the
Galapagos Islands
The Niche
0011 0010 1010 1101 0001 0100 1011
• Ecological niche~ the sum total of
an organism’s use of biotic and abiotic
resources in its environment; its “ecological
role”
√ fundamental~ the set of
resources a population is theoretically
capable of using under ideal conditions
√ realized~ the resources a
population actually uses
• Thus, 2 species cannot coexist in
a community if their niches are
identical
1
2
4
Ex: Barnacle sp. on the coast of Scotland
Succession
0011 0010 1010 1101 0001 0100 1011
• Ecological succession~
transition in species composition over
ecological time
• Primary~ begun in lifeless area; no
soil, perhaps volcanic activity or
retreating glacier
• Secondary~ an existing community
has been cleared by some disturbance that
leaves the soil intact
1
2
4