Ecosystems and Living Organisms
Chapter 4
Evolution
• Genetic changes in a population through time.
• Occurs through natural selection
Overproduction
Variation
Struggle for existence
Differential reproductive success
Evolution
Darwin’s Finches
Evolution
Kingdoms of Life
Biological Communities
Rotting Log Community
Biological Communities
Succession:
How Communities Change over Time
Primary succession –
Lichens
Mosses
Rocks
Biological Communities
Succession: How Communities Change over Time
Primary succession –Rocks
Lichens
Mosses
Grasses
Shrubs
Biological Communities
Succession: How Communities Change over Time
Primary succession –Rocks
Lichens
Mosses
Grasses
Shrubs
Trees
Biological Communities
Secondary Succession
Interactions Among Organisms
Symbiosis –
• one species living in or on another species
• results from coevolution
Interactions Among Organisms
Symbiosis –
Three types
1) Mutualism
Without mycorrhizae With mycorrhizae
Interactions Among Organisms
Symbiosis –
Three types
2) Commensalism
Epiphytes
Interactions Among Organisms
Symbiosis –
Three types
3) Parasitism
Tracheal mites
Interactions Among Organisms
Predation – predators consuming prey
Most common method:Pursuit and Ambush
Interactions Among Organisms
Animals that consume plants = herbivores
Animals that consume animals = carnivores
(can be further subdivided based on prey type, such as an insectivore)
Interactions Among Organisms
Defenses against predators:
Plant defenses –
• spines, thorns
• leathery leaves
• toxic chemicals
• thick waxes
Interactions Among Organisms
Defenses against predators:
Animal defenses –
• armor, spines• toxic chemicals
Interactions Among Organisms
Defenses against predators:
Animal defenses –
• armor, spines• toxic chemicals
• camouflage
• running away
Interactions Among Organisms
Competition –
individuals attempting to utilize common resources
• Intraspecific competition
• Interspecific competition
The Ecological Niche
• An organism’s adaptations, use of resources, lifestyle, and habitat.
Fundamental vs. Realized Niche
Example: Tale of Two Anoles
Green Anole Brown Anole
The Ecological Niche
Fundamental vs. Realized Niche
Fundamental Niche of Green Anole
Fundamental Niche of Brown Anole
Ove
rlap
Brown anole out-competes green anole, therefore . . .
The Ecological Niche
Fundamental vs. Realized Niche
Realized Niche of Green Anole
Ove
rlap Realized
Niche of Brown Anole
The Ecological Niche
Limiting Resources
The Ecological Niche
Competitive Exclusion
The Ecological Niche
Competitive Exclusion
The Ecological Niche
Competitive Exclusion
The Ecological Niche
Resource partitioning
Keystone Species
• Single species that strongly influences an entire community.
• Example: figs
- frugivores depend upon fruit
- usually avoid figs, but during certain times of the year, figs are only species bearing fruit
- if figs were eliminated, many frugivores would die out
Species Richness
Number of different species in a community
Species Richness
Forest Grassland
EC
OT
ON
E
Where edge effect occurs
Typically greater species richness
Species Richness
Species Richness and Ecosystem Services
Ecosystem Ecosystem services
Forests,Grasslands
Purify air / waterProduce / maintain soilAbsorb CO2
Wildlife habitat
Freshwater systems
Moderate water flowMitigate floodingDilute / remove pollutantsDrinking water
Recreation
Species Richness
Species Richness and Community Stability
Greater the richness = Greater the stability