Environmental Issues & Problems
ENV 150
What is environmental
science?
Guillaume Mauger
Today’s Schedule:
1. Review Syllabus, Schedule, Assignments
2. Rehash of last week’s topics
3. Biodiversity and Evolution
Rehash, Lecture 1:
Rehash, Lecture 1:
• Natural Capital = ?
• Natural Capital Degradation
– Caused by …?
Rehash, Lecture 1:
• What is sustainability?
Source: Footprint Network
What is sustainability?
World Commission on Environment and Development Report
Our Common Future, 1987
"development that meets the needs of the present without
compromising the ability of future generations to meet their own
needs."
Rehash, Lecture 1:
• Characteristics of Sustainable
Ecosystems:
-
Biodiversity
Reliance on Solar Energy
Nutrient Cycling
Population Control
Rehash,
Lecture 1:
• Seattle area:
Rehash, Lecture 2:
• Spheres
– Geosphere
– Atmosphere
– Hydrosphere
– Biosphere
Color
Land Use
Dark green
Light green
Pinkish
Bright blue
Thick forest
Vegetation
Urban areas
Ice and snow
Rehash, Lecture 2:
Rehash, Lecture 2:
• Ecosystems:
• Nutrient Cycles
– Components
– Producers (Autotrophs)
– Consumers (Primary, Secondary, Tertiary,
Omnivores)
– Decomposers, Detritus Feeders
– Dynamics
– e.g., Food chain, Trophic Levels
– Productivity: GPP / NPP
– Water
– Carbon
– Nitrogen
– Sulfur
– Phosphorous
Biodiversity and Evolution
What do we mean by “biodiversity”?
U.S. Office of Technology Assessment:
Biological diversity refers to the variety and
variability among living organisms and their
relative frequency. For biological diversity,
these items are organized at many levels,
ranging from complete ecosystems to the
chemical structures that are the molecular
basis of heredity. Thus, the term
encompasses different ecosystems, species,
genes, and their relative abundance.
What do we mean by “biodiversity”?
What do we mean by “biodiversity”?
More than just diversity of species:
• Diversity of ecosystems
• Diversity of species
• Diversity within a species (genetic)
Why is biodiversity important?
Why is biodiversity important?
To humans:
– Provides food, wood, fibers, energy,
medicines
For life on Earth:
– Preserves quality of air/water
– Preserves fertility of soils
– Waste disposal, pest control
Evolution:
The Context
Evolution
• History of
life on Earth:
Evolution
4.5
4
3
2
1
Billions of years ago
0
4.5
4
3
2
1
Billions of years ago
4.5
4
today
• Formation of Earth’s crust, atmosphere and oceans
Evolution
Evolution
3
2
1
Billions of years ago
0
today
• Formation of Earth’s crust, atmosphere and oceans
• Small organic molecules form in the sea
• Large organic molecules form in the sea
• First protocells form in the sea
0
today
Evolution
4.5
4
3
2
1
Billions of years ago
• Formation of Earth’s crust, atmosphere and oceans
• Small organic molecules form in the sea
• Large organic molecule form in the sea
• First protocells form in the sea
• Formation of Earth’s crust, atmosphere and oceans
• Small organic molecules form in the sea
• Large organic molecule form in the sea
• First protocells form in the sea
• Single-cell prokaryotes form in the sea
-Bacteria
-Archaea
• Single-cell prokaryotes form in the sea
• Single-cell eukaryotes form in the seas
-Amoebae
-Ciliates
-Flagellates
-Heliozoa
Cyanobacteria
Credit: Micrographia
2 Amoebae
0
today
Credit: Micrographia
Evolution
4.5
4
3
2
1
Billions of years ago
0
Evolution
today
4.5
4
3
2
1
Billions of years ago
0
today
• Formation of Earth’s crust, atmosphere and oceans
• Small organic molecules form in the sea
• Large organic molecule form in the sea
• First protocells form in the sea
• Formation of Earth’s crust, atmosphere and oceans
• Small organic molecules form in the sea
• Large organic molecule form in the sea
• First protocells form in the sea
• Single-cell prokaryotes form in the sea
• Single-cell eukaryotes form in the seas
• Multicellular organisms form in the seas, and later on land
• Single-cell prokaryotes form in the sea
• Single-cell eukaryotes form in the seas
• Multicellular organisms form in the seas, and later on land
Red algae
Evolution:
Homonids
Credit: Berkeley, Palomar College
4.5
4
3
2
1
Billions of years ago
0
Red algae
Humans
Credit: Berkeley, Palomar College
Phylogeny: study of evolutionary relatedness
today
Source: Reed et al., PLOS Biology
Credit: NASA
How does evolution work?
The process of Evolution
Genetic Mutations:
random changes in the structure or number of DNA molecules in
a cell that can be inherited by offspring
– Random errors in gene replication, or
– External agents: radioactivity, x-rays, or “mutagens”
NOTE: all mutations are RANDOM!
The process of Evolution
The process of Evolution
Natural Selection:
Natural Selection:
– Genetic variability
– Traits must be inheritable
– Trait must lead to differential reproduction
– Genetic variability
– Traits must be inheritable
– Trait must lead to differential reproduction
– Leads to adaptations: heritable traits that
enable survival and reproduction
• Structural, behavioral/sexual, physiological
Structural
adaptations
The process of Evolution
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Natural Selection:
Kona Grosbeak
Akiapolaau
– Genetic variability
– Traits must be inheritable
– Trait must lead to differential reproduction
– Leads to adaptations: heritable traits that
enable survival and reproduction
Crested Honeycreeper
Maui Parrotbill
Apapane
• Structural, behavioral/sexual, physiological
Unknown finch ancestor
Evolution: Genetic variation
how?
• mutations: random changes in the structure or # of
DNA molecules in a cell that can be inherited by
offspring
Evolution: Genetic variation
how?
• mutations: random changes in the structure or # of
DNA molecules in a cell that can be inherited by
offspring
• gene flow: introduced genes from a different
population (same species)
Evolution: Genetic variation
how?
• mutations: random changes in the structure or # of
DNA molecules in a cell that can be inherited by
offspring
• gene flow: introduced genes from a different
population (same species)
• hybridization: 2 distinct taxa crossbreed to produce
fertile offspring
Evolution
• Large gene pool
- Increases biological fitness of the species
• Small gene pool
- Fewer traits for natural selection
- Genetic drift has significant affects
- Increased potential of extinction
Hunted to near extinction,
30,000 to 1,000 in 1900
Evolution: Genetic drift
how?
• random selection
• allows maladaptive traits in small populations
- probability
Worms of different color
over 4 generations:
Common myths about Evolution
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
2. Adaptations occur because they are
needed or wanted (purely based on
advantage)
- chance
3. Evolution follows a clear path of
improvement and order (random, branching
process)
Common myths about Evolution
Common myths about Evolution
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
2. Adaptations occur because they are
needed or wanted (purely based on
2. Adaptations occur because they are
needed or wanted (purely based on
advantage)
advantage)
3. Evolution follows a clear path of
improvement and order (random, branching
process)
3. Evolution follows a clear path of
improvement and order (random, branching
process)
Common myths about Evolution
Common myths about Evolution
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
2. Adaptations occur because they are
needed or wanted (purely based on
2. Adaptations occur because they are
needed or wanted (purely based on
reproductive advantage)
3. Evolution follows a clear path of
improvement and order (random, branching
process)
reproductive advantage)
3. Evolution follows a clear path of
improvement and order (random, branching
process)
Common myths about Evolution
1. Survival of the fittest = “survival of the
strongest” (strongest may not be fittest)
2. Adaptations occur because they are
needed or wanted (purely based on
reproductive advantage)
3. Evolution follows a clear path of
improvement and order (random, branching
process)
Evolution
Behavioral
Physiological
Structural
Speciation through
adaptations
Genetic drift
Speciation through
chance/probability
Coevolution
Interacting species engage in a
back and forth genetic contest
Convergent evolution
Organisms not closely related,
independently evolve similar traits
due to similar ecological niches
Speciation due to human selection