nsported
to a different
environment
Isolation & time
Adapted to wind
Adapted to calm & shade
Variability
in the
population
Some Evidence for Evolution
Biological variability.
Record of past environmental
change.
Variations in Earths
Environment Over Time Lecture 5
Biological Variability
Biological Variability
Where you might see it:
Domesticated animals, e.g. dog
breeds.
Food crops, e.g. cabbages.
Disease bacteria, e.g. disease
strains.
Insects, e.g. insecticide
resistance. Difficult to see:
Differences subtle
Change gradual
Example of Domestic Variability
Canis familiaris
Wild
Cabbage
Brassica oleracea
Var. oleracea
Breeding
Kohlrabi
Brussels
Sprouts
Cauliflower
Cabbage
Broccoli
Kale
Collards
Bred Variations of Cabbage
Insecticide Resistance
Insecticide Resistance
DDT (
d
ichloro-
d
iphenyl-
t
richloroethane)
Used against mosquitoes
to control malaria.
With repeated usage,
mosquitoes became
resistant to DDT.
Paul Müller
Changes in Environment
Changes in Environment
Temporal Changes
: Changes
occurring over time.
Spatial Changes
: Changes
occurring across landscape,
e.g. when you drive from beach
to the mountains.
Note: How much and how
quickly change occurs. Lecture 5
Scales of Temporal Changes
Scales of Temporal Changes
Long Term
: Geological scale,
measured in millions of years.
Medium Term
: Changes
measured in annual to
thousands of years.
Short Term
: Hours, days,
monthly.
Long Time Scales
Long Time Scales
Earths Age: 5 billion yrs
250 million yrs
dinosaurs
65 million yrs
Long-Term Change
Long-Term Change
major tectonic plates
major tectonic plates
Plate Tectonics
Plate Tectonics
Alfred Wegener
proposed theory of
plate tectonics, e.g.
movement of
continents.
Ridiculed by most.
(1880-1930)
Pangaea (all of the earth)
245-208 mya
India
India
conifer trees
first dinosaurs, insects
Triassic Period
Pangaea Continents
Pangaea Continents Lecture 5
Pangaea (coming apart)
208-145 mya
India
India
conifer trees
dominate, early
flowering plants
dinosaurs dominate,
early birds,
mammals
Jurassic Period
Continents Further Apart
Continents Further Apart
more flowering plants
dinosaurs extinct at
end of era
145-65 mya
India
India
End of Cretaceous Period
Present Day Continents
Present Day Continents
diversification of
flowering plants,
mammals, birds,
pollinating insects
India
collides
10 million
yrs ago
India
collides
10 million
yrs ago
65 mya - present
Problems with Plate
Tectonics Hypothesis
Problems with Plate
Tectonics Hypothesis
No mechanism for movement
Centripetal force?
Tidal action?
Both too weak.
Miscalculation of rates from
original flawed data: 10-100X
too fast.
Revival of Continental Drift
Revival of Continental Drift
Increase exploration from
1950 to present:
Earths crust
Ocean floor
Solid plates float on molten
inner core.
By 1960s hypothesis finally
accepted.
Indias Changing Climate
Indias Changing Climate
Wet
Tropical
Dry
Temperate
Wet
Temperate
Dry
Antarctic
Climate
Location
isolated
joined
movement took about 250 million yrs Lecture 5
Indias Changing Climate
Indias Changing Climate
Conifers
Flowering plants
Dinosaurs
Birds
Mammals
Insects
Continents Changed
Shape & Characteristics
Continents Changed
Shape & Characteristics
North America Covered
With Shallow Seas
North America Covered
With Shallow Seas
shallow
sea
shallow
sea
land
land
Rocky
Mountains
Rocky
Mountains
Appalachian
Mountains
Appalachian
Mountains
200 mya
Periodic Tilting of
Tectonic Plates
Periodic Tilting of
Tectonic Plates
Flood Drain Cycles
Spatial Changes Along Coastline
Baldwin Park Hana Hwy
Environmental Change
Environmental Change
Medium Term
Temperature
Light
Rainfall
Substrate or
medium Lecture 5
Ocean Currents-Surface
Ocean Currents-Surface
surface currents driven by wind
surface currents driven by wind
Ocean Currents-Deep
Ocean Currents-Deep
driven by salinity, temperature
driven by salinity, temperature
Global Conveyor
Global Conveyor
warm
cool
If disrupted, can cause ice age in < 10 years.
Environmental Change
Environmental Change
Short Term
Earth orbits sun
in 365 days.
23.5 degree tilt
seasonality
seasonality
Northern summer
Southern summer
Seasonal Changes
Seasonal Changes
Wind Patterns
Wind Patterns
Winter pattern
Winter pattern
Wind + Topography = Rain
Wind + Topography = Rain
moisture precipitates
when it is cooled
moisture precipitates
when it is cooled Lecture 5
Cloud Formation
Cloud Formation
http://fc.intermedia.sa.it/~malfano/Progetto_scool/formazione-nuvole.gif
Cloud Formation and Rain
Shadow
Cloud Formation and Rain
Shadow
(orographic lifting)
cools & rainfall
descending
air dries
very dry
wet
dry
warm
trades
Cloud Formation and Rain
Shadow
Cloud Formation and Rain
Shadow
Aspect: Where there is
snow facing slope is
important
brown and
dried desert
Snow capped
Mountain
peaks
Far side of mountain
40 100 of
accumulated snow
Evolutionary Development
Evolutionary Development
Summary
Variability exist within
species.
Temporal and spatial scales
are important.
Long term environmental
change leads to spatial
change.
Rate of change is important.