Chapter 4 Notes - Fulton County Schools

tanktherapistΒιοτεχνολογία

23 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

72 εμφανίσεις

Evolution

Chapter 4

How Did We Become Such a
Powerful Species So Quickly?

3 Main Adaptive Traits



Opposable Thumbs



Ability to Walk Upright



Intelligence (Complex
Brains)


Fig. 4
-
1, p. 63

How Do We Know Which
Organisms Lived in the Past?



Fossil record



Radiometric dating



Ice cores



DNA studies


Fig. 4
-
2, p. 65

Origins of Life



Chemical evolution (1 billion yrs)



Biological evolution (3.7 billion years)



Considerable evidence suggests
that life developed in 2 phases
over the past 4.6
-
4.7 billion years.

Question #1
:


What is biological evolution by
natural selection, and how has it led
to the current diversity of organisms
on earth?


Include the importance of variation
within the gene pool and mutation on
microevolution and how this relates
to adaptations.




Biological Evolution



Biological Evolution



Theory of Evolution



Microevolution


Mutations



Natural Selection



1)
Variation exists for a trait


2)
Trait is heritable


can be passed on
to offspring


3)
Individuals w/ trait are better able to
survive, reproduce & spread the trait

In a polluted environment…

Adaptations

Natural selection works on
individuals
,
Evolution occurs in
populations
!



Adaptations



Coevolution

How microevolution occurs…


Genes mutate,



Individuals are selected,



and Populations evolve!

Question #2
:


How does the formation of
new species (speciation) and
extinction of species affect
biodiversity?


Explain the mechanism of
speciation and how this
increases biodiversity.



Macroevolution


Speciation


Increases biodiversity



Extinction


Decreases biodiversity




Speciation


Extinction

=
Current Biodiversity

Mechanism of Speciation


Geographic Isolation


2 groups from same species become physically
separated for long time period



Reproductive Isolation


Mutation & natural selection act on separated
populations


Each group adapts to different environmental
conditions


Over time, leads to formation of 2 new species

Fig. 4
-
7, p. 71

Spreads northward

and southward

and separates

Arctic Fox

Gray Fox

Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.

Adapted to heat
through
lightweight fur
and long ears,
legs, and nose,
which give off
more heat.

Different environmental

conditions lead to different

selective pressures and evolution

into two different species.

Northern

population

Southern

population

Early fox

population

Geographic Isolation can Lead to
Speciation

Question #3
:


Define
ecological niche
.



Distinguish between
fundamental niche

and
realized niche
.


List the factors that determine
the realized niche.



Ecological Niches and
Adaptation


Ecological Niche
(Occupation)



Habitats

(Address)

Fundamental
Niche


Realized
Niche

Question #4
:


Distinguish between a
specialist

and a
generalist.

Evaluate the conditions that
favor these two approaches.



Generalist Species


Broad Niches


can live in many places


can eat a variety of foods


can tolerate a wide range of environmental
conditions


Cockroaches: Nature’s Ultimate
Survivors

Fig. 4
-
A, p. 69

Specialist Species


Occupy narrow niches


(may only have 1 possible habitat)



use few food types


can only tolerate a narrow range of
environmental conditions


more prone to extinction when
environment changes


reduces competition &


allows for sharing of


limited resources


Specialized Feeding Niches for Birds

Black skimmer

seizes small fish

at water surface

Flamingo

feeds on

minute

organisms

in mud

Scaup and other

diving ducks feed on

mollusks, crustaceans,

and aquatic vegetation

Brown pelican dives for fish,

which it locates from the air

Avocet sweeps bill through

mud and surface water in

search of small crustaceans,

insects, and seeds

Louisiana heron wades into

water to seize small fish

Oystercatcher feeds on

clams, mussels, and

other shellfish into which

it pries its narrow beak

Dowitcher probes deeply

into mud in search of

snails, marine worms,

and small crustaceans


Knot (a sandpiper) picks up

worms and small crustaceans

left by receding tide

Herring gull is a

tireless scavenger

Ruddy turnstone
searches

under shells and
pebbles for small
invertebrates

Piping plover feeds

on insects and tiny

crustaceans on

sandy beaches

If resources are limited, natural selection
favors specialized species.

Fig. 4
-
6, p. 70

Unknown finch ancestor

Fruit and seed eaters

Insect and nectar eaters

Greater Koa
-
finch

Kona Grosbeak

Akiapolaau

Maui Parrotbill

Kuai Akialaoa

Crested Honeycreeper

Apapane

Amakihi

Evolutionary Divergence of
Honeycreepers

Broad and Narrow Niches


Generalist species


Better able to survive rapidly changing
environmental conditions



Specialist species


Benefit under constant environmental
conditions (reduces competition)

Fig. 4
-
4, p. 68

Niche

separation

Specialist species

with a narrow niche

Generalist species

with a broad niche

Niche

breadth

Region of

niche overlap

Niches of Specialist and
Generalist Species

Resource use

Number of individuals

Limits on Adaptation


A population’s ability to adapt is limited
by it’s gene pool & the speed with which
it can reproduce



Natural selection can only work on
currently existing traits (beneficial
adaptations are rare)



Rapid reproducers are able to adapt
much more quickly to changes in
environment

Question #5
:


How is “survival of the fittest”
different from the idea of
“progress to perfection”?



Evolution Misconceptions


Survival of the “fittest” refers to
reproductive success


not strength!



Evolution doesn’t lead to genetic
perfection, just works to select for best
traits for the current environmental
conditions.


Organism best suited to environment,
survives & reproduces. Helpful traits are
then passed on!

Question #6
:


How can genetic engineering
affect our ecosystems?



Future of Evolution


Genetic Engineering (gene splicing)



Genetically Modified Organisms
(GMOs)



Ethical concerns

Ecological Lesson


Whenever we intervene in nature, we
must pause & ask “What happens next?”



Evaluate possible unintended
consequences of biotechnology.