1. The Living World: Biodiversity
Unit 2

2. Topics 2.1 – Introduction to Biodiversity
2.5 – Natural Disturbances to Ecosystems
(C. 4.1 – 4.3)
(C. 4.4)
2.2 – Ecosystem Services
2.6 – Adaptations
(C. 1)
2.3 – Island Biogeography
2.7 – Ecological Succession
2.4 – Ecological Tolerance
(C. 7.2)
(C. 7.1)

3. 2.1 – Introduction to Biodiversity

4. Levels of biodiversity
There are four levels of biodiversity:
Genetic: the variety of genes in a given species
Species: the variety of species in a given ecosystem
Habitat: the variety of habitats in a given region
Functional: the variety of processes

5. Species Diversity Measurements
To measure species diversity, environmental scientists use two measures:
Species richness – the number of species in a defined area
Species evenness – to tell is an area is numerically dominated by one species or whether all species have similar abundance

6. Factors Influencing Species Diversity
Latitude/NPP
Habitat diversity and rate of disturbance
Time
Species area curve
Pollution

7. Generalists and Specialists
Niche generalists – have a broad diet and wide habitat preferences
Niche specialists – have narrow diets and highly specific habitat preferences

8. 2.2 – Ecosystem Services
(C. 1)

9. How Wolves Change Rivers
Disappearing Frogs
How Wolves Change Rivers
Chapter 8: Community Ecology

10. Provisioning Regulating Cultural Supporting – Ecosystem Services
services that make it possible for ecosystems to continue to perform their services.

11. Wealth of a Nation

12. Easter Island

13. 2.3 – Island Biogeography

14. Theory of Island Biogeography
Factors determining equilibrium
Species diversity
Island size/species area curve = greater size, greater habitat, greater niches, greater diversity
Island distance from mainland: closer means greater immigration to ‘replace’ species

15. Ecological Niches Habitat vs niche
Every species has a range of tolerance, or limits to abiotic conditions they can tolerate.
Fundamental niche - ideal
Realized niche - actual

16. Species Types Native species/ Endemic/Indigenous
Non- native/Alien/Exotic/Inv asive
Indicator
Keystone
Foundation
Lake trout larva (upper) shows abnormal abdominal swelling when exposed to very low concentrations of PCBs, as compared to a normal larva (lower) not exposed.

17. 2.4 – Ecological Tolerance

18. Limiting Factors Light Temperature DO Nutrients Predators Prey
Law of Tolerance – Do the physical or chemical factors fall within the range tolerated by the species?
Limiting Factors
Light
Temperature DO
Nutrients
Predators
Prey

19. 2.5 – Natural Disturbances to Ecosystems

20. Scales Natural Disruptions Periodic – Repeats at regular intervals
Tides
Random – Occurring sporadically
Volcanic eruption
Episodic – repeats at irregular intervals
El Nino/Sea level

21. 2.6 – Adaptations
(C. 4.4)

22. Evolution by natural selection
Organisms produce more offspring than can survive
Not all offspring can survive since there exists a ‘struggle for survival’
Individuals vary in traits
Some traits are positively selected for (advantageous) and individuals then have more offspring
Over time (generations), the gene for the advantageous trait increases in frequency

24. Five Fingers of Evolution
Chapter 8: Community Ecology

25. Evolution by artificial selection
When humans determine which individuals breed we call this process evolution by artificial selection
Pros – more efficient crops, useful livestock, aesthetically pleasing species
Cons:
Overuse of the herbicide Roundup (glyphosate) has led to herbicide-resistant weeds
Overuse of antibiotics has led to drug-resistant bacteria (MRSA)

26. 2.7 – Ecological Succession

27. Ecological Succession - Community Transitions
Primary Succession
Bare rock is colonized by pioneer species
Algae, lichens and mosses
They excrete acids which help break down the rock into soil.
Mid-successional plants then move in as they are easily dispersed
Grasses and wildflowers
Then the ecosystem gradually matures depending upon temperature and rainfall
Shrubs
Aspen, cherry and young pine trees
Beech and maple trees

28. Ecological Succession - Community Transitions
Secondary Succession
Most common
Occurs in areas that have experienced a disturbance but have not lost their soil
Hurricanes, floods, forest fires, abandoned farms
Mid-successional plants then move in as they are easily dispersed
Grasses and wildflowers
Then the ecosystem gradually matures depending upon temperature and rainfall
Shrubs
Aspen, cherry and young pine trees (also referred to as pioneer species as they are readily able to colonize new areas)
Beech and maple trees

29. Aquatic Succession Intertidal systems
Disturbances can cause exposure to air, turnover of rocks
Diatoms, red and green algae are first to colonize
Followed by barnacles
In lakes, glaciers carve out a lake
Which is colonized by aquatic plants
Plants and erosion slowly fill the lake with sediment
Eventually it may become a terrestrial ecosystem

30. Species Types Native species/ Endemic/Indigenous
Non- native/Alien/Exotic/Inv asive
Indicator
Keystone
Foundation
Lake trout larva (upper) shows abnormal abdominal swelling when exposed to very low concentrations of PCBs, as compared to a normal larva (lower) not exposed.

31. Rates of Succession and Disturbance
Facilitation
Legumes add nitrogen to soil
Inhibition
Red-tide
Intermediate disturbance hypothesis
Frequent, moderate disturbances increase species diversity

32. Community Development via Succession
Disturbance
Secondary
Succession
New Community
Climax Community
Primary Succession
IDH allows for greater ecosystem complexity, which leads to greater species diversity

33. Differences in Ecological Succession
Late Succession (mature/climax community)
High
Ecosystem complexity
Species diversity
Number of niches
Trophic structure
Low
productivity
Succession (change in species composition) is a perpetual process in nature
Early Succession (immature)
Low
Ecosystem complexity
Species diversity
Number of niches
Trophic structure
High
Productivity