Download Ch 5 Notes

Chapter 5: Ecosystems and the Living Environment
YOUR RESPONSIBILITY….. PAGES 81-88 AND 92-94 & ALL CASE IN POINTS/ENVIROBREIFS!
Evolution
- Dates back to Aristotle.
-___________________ proposed the mechanism that is accepted today.
Main idea: inherited traits favorable to survival in a given environment tend to be
preserved, and unfavorable ones are eliminated.
- “________________ of the _________________”
- Results in ADAPTATION =
- Accumulation of modifications may result in a _______________________
Darwin proposed his theory in:
Main Idea: More favorable genes increase in frequency in successive generations, and fewer unfavorable
genes survive.
- Well-accepted in science
- Mechanisms of evolution are still debated.
EVOLUTION BY NATURAL SELECTION - Darwin’s 4 observations about nature:
1. Overproduction
2. Variation
3. Limits to Population Growth (Struggle for Survival)
4. Differential Reproductive Success
TYPES of NATURAL SELECTION
Stabilizing
Selection
Diversifying (Disruptive)
Selection
-It pays to be _______________
-Occurs when the environment
changes little, and most species
are well-adapted.
-Often mistaken for no selection.
-It pays to be _______________
-It pays to be _______________
Example
Description
Directional
Selection
TYPES OF SPECIES EVOLUTION
Type
Description
Convergent
Evolution
Divergent
Evolution
Adaptive Radiation (Special Type of Divergent
Evolution)
Co-Evolution
What is the difference between Natural Selection & Species Evolution??
Example
Biological Communities
•
Species compete with one another for:
•
Vary greatly in _________, lack precise ________________, and are rarely completely ______________
- they interact and influence one another.
•
There are communities nestled within one another like a set of Chinese boxes.
Succession =
-As the environment changes, the community living in that environment changes as well.
PRIMARY (1°)
Pioneer Species:
Rock  Lichens  Soil  Grass  Non-Woody Plants  Pine Trees  Hardwood Trees
Secondary (2°)
Pioneer Species:
Grass  Non-Woody Plants  Pine Trees  Hardwood Trees


ORDER UP Pages 89-92
#
QUESTION
Keystone Species & Symbiosis
ANSWER
Keystone Species
•
Species that are more crucial to the _______________________________________________________.
•
Species that are vital in _________________________________________________________________.
•
Not the most abundant organisms but exert a profound influence on the entire ecosystem b/c they often:
Wolves
Sea Otters
Symbiotic Relationships
1.
(
/
)
2.
(
/
)
3.
(
/
)
Predation
Strategies (Pursuit & Ambush)
Adaptations for Plants
Warning Coloration & Mimicry
Adaptations for Animals
Niche
•
•
•
•
Same as Habitat??
Does it relate to Habitat??
What an organism does – it’s “_______”
Includes ______________ and _______________ factors
•
NO TWO SPECIES CAN SHARE EXACTLY THE SAME NICHE!
•
Species CAN have similar niches.
Fundamental vs. Realized Niche
Limiting Factor
Density Dependent:
Density Independent:
Competition
Intraspecific
VS
Interspecific
Competitive Exclusion
Species Richness
•
•
The number of species present in a community
Ex: Tropical Rainforest & Coral Reefs VS Geographically isolated islands & Mountaintops
•
Factors that affect species richness:
1.
2.
3.
4.
5.
6.
Which ecosystem has higher
richness? Evenness?
1. Abundance of Potential Ecological Niches
•
A more ______________________________community
will have more varied food & habitat sources, allowing a
_______________________.
– Ex: forest vs. grassland
2. Near the Margins of Adjacent Communities
•
Here, species richness is usually _____________ as compared to the center.
– ECOTONE =
– Why would species richness be greater here??
– Change in species composition at the ecotones = __________________________
3. Geographical Isolation
•
Species Richness is _____________ related to this.
•
Isolated communities tend to be less diverse… why???
•
Geographical Isolation can lead to __________________!!!!!
4. One species is Dominant over others
•
This _____________ species richness! Why???
•
Chihuahuan Desert
5. Habitat Stress
•
This _____________ species richness! Why???
6. Geological History
•
A region that has gone through many climate changes will have ____________ species richness… why??
•
Name some places with…
High species richness?
Low species richness?
**Summary** Species richness is great when…
–
–
–
There are _____________ potential ecological niches
You’re _______________ adjacent communities
The community is / is not isolated
–
–
–
The community is / is not severely stressed
There is _____________ species dominance over others
Communities have _______________ geologic history
Effects of Species Richness on Ecosystem Services & Community Stability
•
The greater the ecosystem’s Species Richness, the…
o ____________ the ecosystem’s ability to supply Ecosystem Services.
o ____________ the Community Stability (ability to withstand environmental disturbances)