Chapter 4
Ecosystems and Living Organisms
Evolution

The cumulative genetic changes that
occur in a ______________

Natural Selection


Individuals with more favorable genetic traits
are more likely to survive and reproduce
Frequency of favorable traits increase in
subsequent generations
Natural Selection

Based on 4 observations about the
natural world:
1.
2.
3.
4.
High Reproductive Capacity
Heritable Variation
Limits on Population Growth
Differential Reproductive Success
Natural Selection
The Modern Synthesis
Domains of Life
Biological Communities
Community Interaction in Oak Forest
Ecological Niche

The totality of an organism’s adaptations,
its use of resources, and the lifestyle to
which it is fitted


Physical, chemical, biological factors needed
to survive
Habitat
Ecological Niche



Fundamental niche
VS
Realized niche
Ex: Green Anole and Brown Anole
Ecological Niche

Green Anole and Brown Anole
Limiting Resources

___________________________________
___________________________________
___________________________________
Interspecific Competition
____________________________________________________________________
Competitive Exclusion & Resource Petitioning

Competitive Exclusion


One species excludes another from a portion of the
same niche as a result of competition for resources
Resource Partitioning (below)

Coexisting species’ niche differ from each other in
some way
Symbiosis

An intimate relationship between 2 or
more species


Participants may be benefited, harmed or
unaffected by the relationship
Result of coevolution
Interdependent evolution of 2 interacting species
Symbiosis

Three types of symbiosis
 Mutualism______

Commensalism-
_______

Parasitism-
_______
Mutualism


__________________________________
__________________________________
Ex: Mycorrihzal fungi and plant roots
Commensalism

______________________________________
______________________________________
__________________

Ex: epiphytes and tropical trees
Parasitism

___________________________________
___________________________________


Parasites rarely kill their hosts
Ex: ________
Predation




The consumption of one species by
another
“arms race”
pursuit and ambush
specific defenses against predation
through evolution
Plant Defenses Against Herbivores


Plants cannot flee predators
Adaptations


___________________________________
_____________________________________
_____________________________________
Defensive Adaptation of Animals


Fleeing or running
Mechanical defenses




Ex: quills of porcupines, shell of turtles
Living in groups (herding/flocking)
Camouflage
Chemical defenses poisons

Ex: brightly colored poison
arrow frog
Camouflage
Mimicry
Keystone Species

__________________________________
__________________________________

More important to the community than what
would be expected based on abundance
Species Richness

The number of
species in a
community
Community Development


Succession:
___________________________________
___________________________________
Two types of succession


Primary succession
Secondary succession
1
3
2
Primary Succession
2.
Bare rock with lichen
Grasses and shrubs
3.
Forest community
1.
Secondary Succession

__________________________________
__________________________________
__________________________________

Generally occurs more rapidly than
primary succession
Secondary Succession of
an abandoned farm field
in North Carolina