Transcript 4.3 & 4.4 Notes

4-3 How Do Geological Processes and
Climate Change Affect Evolution?
• Concept 4-3 Tectonic plate movements, volcanic
eruptions, earthquakes, and climate change have
shifted wildlife habitats, wiped out large numbers of
species, and created opportunities for the evolution
of new species.
Geologic Processes Affect Natural
Selection
• The earth’s surface has changed dramatically over its
long history due to the movement of
_____________
plates…
tectonic
• Series of gigantic solid plates broken apart by
_____________
rock flowing from the earth’s interior
molten
• For hundreds of millions of years, these plates have
mantle
drifted slowly on the planet’s _________________
Movement of the Earth’s Continents
over Millions of Years
Fig. 4-8, p. 89
Geologic Processes Affect Natural
Selection
• Tectonic plate drift has two important effects on
evolution…
• First…locations (________________)
of continents and
latitudes
oceans have shifted, exposing them to different
climates
_______________
move
• Second… species physically ___________
with the
continents and their populations must ____________
adapt
new environments…may eventually form new
to ______
species through natural selection
Geologic Processes Affect Natural
Selection
• Plate movement may also alter populations
through…
shifts
• Earthquakes …due to _________
which may cause
fissures
• Can __________________
or isolate members of a
separate
population
• Volcanic eruptions along the ________________
of
boundaries
plates
• can ____________
or wipe out populations
destroy
Climate Change and Catastrophes
Affect Natural Selection
• The earth’s changing climate has also affected
populations
• Sometimes it has cooled and covered much of the
earth with _______________
ice
glacial
• Other times it has warmed, melted the ice, and
raised
drastically _______________
sea levels
• Such cooling and heating periods have led to the
advance and retreat of ice sheets at _________
higher
northern
latitudes over much of the _______________
hemisphere
Changes in Ice Coverage in the Northern Hemisphere
During the last 18,000 Years
Fig. 4-9, p. 89
asteroid
• Catastrophic events, such as _________________
impact, have also affected populations and natural
selection…
• Species may have been wiped out
• Or may have caused shifts in the _________________
locations
of ecosystems creating opportunities for the
evolution
________________
of new species
Science Focus: Earth Is Just Right
for Life to Thrive
• Temperature range: most life on earth requires a
freezing
temp. range between the ________________
and
boiling
_____________
points of water
moderate
• Orbit size: ________________
temperature (Venus is
too hot and Mars is too cold)
• Liquid water: necessary for life (Venus has water
_________
and Mars has _________)
vapor
ice
fast
• Rotation speed: _____________
enough to prevent
the sun from overheating earth’s surface
• Size: enough _______________
mass to keep our
gravitational
atmosphere from flying off into space
4-4 How Do Speciation, Extinction, and
Human Activities Affect Biodiversity?
• Concept 4-4A As environmental conditions change,
the balance between formation of new species and
extinction of existing species determines the earth’s
biodiversity.
• Concept 4-4B Human activities can decrease
biodiversity by causing the extinction of many species
and by destroying or degrading habitats needed for
the development of new species.
How Do New Species Evolve?
Under certain situations, natural selection can lead
to an entirely new species
splits
• Speciation: one species ____________
into two or
more species
• For sexually reproducing organisms, a new species has
formed when one population has evolved to the point
no longer
where it can __________________
breed and
produce fertile offspring with a previous population
How Do New Species Evolve?
The most common way that speciation occurs is when a
barrier
migration prevents the
_______________
or distant ________________
genes
flow of ______________
between two or more populations
Occurs in Two Phases
• Geographic isolation: happens first; ________________
physical
isolation of populations for a long period
• Reproductive isolation: ________________
and natural
mutations
selection in geographically isolated populations lead to inability
to produce viable offspring when members of two different
populations mate
Adapted to cold through
heavier fur, short ears,
short legs, and short
nose. White fur matches
snow for camouflage.
Arctic Fox
Northern
population
Early fox
population
Different environmental
conditions lead to different
selective pressures and
evolution into two different
species.
Spreads
northward and
southward and
separates
Gray Fox
Southern
population
Adapted to heat through
lightweight fur and long
ears, legs, and nose,
which give off more heat.
Fig. 4-10, p. 91
• For species that reproduce ______________,
slowly
speciation is hard to document and study
• Humans sometimes control the process with
artificial
_________________
selection
• Humans select desirable traits (in wheat, fruit, dogs,
etc.) and use ________________
breeding or
selective
crossbreeding to generate populations with the
desired traits
Desired trait (color)
Cross
Pear breeding
Apple
Offspring
Best result
Cross
breeding
New
offspring
Desired
result
Fig. 4-C, p. 92
Science Focus: Changing the Genetic
Traits of Populations
•
Genetic engineering can be used to ___________
speed
up our ability to manipulate genes
•
Alteration of an organism’s genetic material by
adding, deleting, or changing segments of its DNA
• Consider
•
•
•
•
Ethics
Morals
Privacy issues
Harmful effects
Human
growth
hormone
gene
Extinction is Forever
• Another process affecting the number and types of
species on earth is extinction
• Biological extinction…a process in which an entire
species ________________
to exist
ceases
• Local extinction…a species becomes extinct over a
large area, but not _________________
globally
• Endemic species …found only in one area
• Exist on islands other unique areas
• Particularly vulnerable to extinction because they are
migrate
unlikely to ____________
or adapt in the face of
rapidly changing environmental conditions
Golden Toad of Costa Rica, Extinct
Lived in Costa Rica’s
protected ________
high
altitude preserve,
but may have
become extinct
when its habitat
dried up
Fig. 4-11, p. 92
Extinction is Forever
• Background extinction: typical ________
rate of
low
extinction
• Natural process
rise
• Mass extinction: significant ____________
in
extinction rates above the background level
• often catastrophic, widespread, global events
• 25 to 95% of all species are wiped out world wide in a
few million years or less
3
5
• At least ______,
probably ______
mass extinctions
Review Questions
• How has plate tectonic movement affected
populations over time?
Populations have been exposed to different climates
Volcanoes/earthquakes
• What is the difference between geographic and
reproductive isolation?
Physical isolation
Mutations that lead to an inability
to produce viable offspring
Review Questions
• What is the difference between artificial selection
and genetic engineering?
Altering DNA to
change traits
Selecting/breeding
desirable traits
“slow”
• Why are endemic species vulnerable to extinction?
They live in remote locations and may have
difficulty migrating or adapting to environmental
changes