Transcript INTRO TO ECOLOGY 2 - Downtown Magnets High School

Species
Diversity and
Succession
Genetic Diversity
-Variability in
genetic makeup
among
individuals in a
pop.
-If too little DNA
differences, can
lead to genetic
bottleneck
extinction.
Bottleneck Effect
Causes of
Bottlenecks
 Mass
hunting
 Sudden,
natural cause
(hurricanes,
tornadoes)
 Loss of food
source/habitat
Species Diversity
# of Species in an Area
• Tropical rain forest/coral reefs = HIGH
diversity, High number of species
Deserts and mountain tops = LOW diversity,
Low number of species
•
•
Ecotone
•
Transitional
zone where 2
or more
communities
meet
–Intertidal
zones
Factors That Determine Species
Diversity
•Habitat stress
•Available niches
•Dominance of
species
•Geological history
Mountain Lion
Stress
Species
•Considered
separate species if they
cannot interbreed
•Same species create viable offspring
NO Dog-Cat
Babies!
YES Panda
Babies!
Exceptions to the Rule
Liger
Mule
Zorse
Grolar/Pizzly
Bear?
Communities Change Over Time
Succession: a process of
community development
that involves a changing
sequence of species
Primary Succession
Starts with new land.
• Species land on new material and
colonize (pioneer community).
Starts with lichens, moss, and progresses
to large trees after 1,000’s of years.
•
•
1) Lichens: Can be N fixers  Put
Nitrate into soil for other plants to
grow! Can also measure air poll.
2) Small Shrubs and mosses (little
roots), provide habitat
3) Young pine trees more habitat
4) Mature hardwood and deciduous
forests climax community
Secondary Succession
Starts with already formed land.
Species land on disturbed material.
Disturbance usually caused by fires,
storms, and man.
•
•
•
Fire Succession in Chaparral
•
Needed for:
–Reproduction
–Clearing out
competitors
–Germination
(seed
sprouting)
As Ecosystems Mature
•
1.
2.
3.
4.
Increase in:
Diversity &
pop numbers
System
stability
Biomass
Nutrient Hold
Capacity