Download FORMATION of NEW SPECIES

GUIDED READING: CHAPTER 7.2
HOW DOES EVOLUTION HAPPEN
Directions: Read pages 158-163 of your textbook and complete the following reading notes. Draw
pictures to help you remember each vocabulary word.
The early 1800’s was a time of:
great scientific discovery
CHARLES DARWIN
Claim to fame:
proposed the “Theory of Evolution by Natural Selection”
Name of ship & years
of voyage:
Sailed on the HMS Beagle from 1831-1836
Type of scientist
(name & explain):
naturalist – a scientist who studies nature
During his voyage Darwin
thousands of plant & animal samples; he kept
detailed notes of his observations
collected:
Islands he visited:
(name & location)
Darwin’s observations about
the plants & animals he saw:
Darwin’s specific observations
about finches there were:
Darwin thought the finches
were descendents of:
Darwin thought that over many
generations the birds had:
Galapagos Islands (965 km west of Ecuador in
South America)
animals & plants on the Galapagos Islands were
very similar, yet not identical to those on the
nearby South American mainland
the finches on the islands were different not
only than those in Ecuador but also from each other
the South American mainland finches (blown over
by a storm)
adapted to the various ways of living on the Island
(took many generations)
DARWIN LEARNED FROM:
1.) Farmers & Animal/Plant Breeders
A trait is:
(define & draw)
Selective breeding is:
(define and draw)
a distinguishing quality that can be
passed from generation to generation
the breeding of organisms for certain
desirable traits (i.e. plump popcorn
kernels)
direct and shape these traits & make dramatic
farmers & breeders had the changes in animals & plants in just a few short
ability to:
generations
Darwin was impressed that
He thought wild animals could
change in similar ways but:
the process would take much longer because
variations would be due to chance
2.) Geologists
Geologosist had evidence that
the Earth was:
From Lyell’s book, Principles
of Geology, Darwin learned:
This info. was important to
Darwin because:
Earth was much older than anyone had imagined
Earth had been formed by natural processes over
a long period of time
he thought that populations of organisms changed
very slowly, requiring a lot of time
3.) Thomas Malthus
In an essay called, Essay on
the Principles of Population,
Malthus proposed:
humans have the potential to reproduce beyond
the capacity of their food supplies
Things that affect the size
of the human population:
From this principle, Darwin
realized:
death caused by starvation, disease and war
other animal species were also capable of
producing too many offspring
Things that affect the size
of animal populations:
death caused by starvation, disease and predators
Because of these things,
only a limited number survive to reproduce offspring of the survivors inherit traits that help
them survive in their environment
Darwin reasoned:
Natural selection is:
(define with glossary and draw)
List & Describe the four steps
of Natural Selection
the process by which organisms with
favorable traits survive & reproduce at a
higher rate than organisms without
favorable traits
1.) OVERPRODUCTION – each species produces
more offspring than will survive to maturity
2.) GENETIC VARIATION – individuals within a
population are slightly different than one another;
each individual has a unique combination of traits.
Some traits increase chances of survival, other
decrease chances of survival. (Variations are
genetic & can be inherited.)
3.) STRUGGLE TO SURVIVE – natural environment
doesn’t have enough food, water, and other
resources to support all organisms; others are
killed by other organisms. Only some organisms
survive into adulthood.
4.) SUCCESSFUL REPRODUCTION – Key to
natural selection! Individuals that are well adapted
to their environment (better traits for the
environment) are more likely to survive and
reproduce; those not well adapted are more likely
to die early or produce few offspring
OTHER EVIDENCE:
Scientists in the 1930’s & 1940’s
combined principles of:
the principles of genetic variation
with Darwin’s theory of Evolution by Natural Selection.
The combination of principles
explained:
A mutation is:
(define with glossary & draw)
that the variations Darwin observed within a
species are caused by mutation
a change in the order of the bases in an
organism’s DNA; deletion, insertion, or
substitution
GUIDED READING: CHAPTER 7.3
NATURAL SELECTION IN ACTION
Directions: Read pages 164-167 of your textbook and complete the following reading notes. Draw
pictures to help you remember each vocabulary word.
The theory of Natural Selection
explains:
how a population changes over many generations
in response to its environment (members tend
to be well adapted to the environment because of
natural selection)
EXAMPLES:
1. Insecticide resistance:
Insecticides that once worked to kill insects no longer do.
There are over 500 species that have become resistant
Reason they quickly develop it: produce many offspring & usually have a short
generation time
Generation time is:
(define with glossary & draw)
2. Adaptation to pollution
Summarize why the peppered
moth is an example of this:
the period between the birth of one
generation and the birth of the next
generation
pollution changed the environment – from light to
dark background. The dark pepper moths were
able to blend in to their environment – light
peppered were not. Population changed from white
being the highest percent to dark being the
highest percentage.
FORMATION of NEW SPECIES
Speciation is:
(define with glossary & draw)
Three steps of speciation:
(name & describe)
the process by which two populations of
the same species become so different
that they can no longer interbreed.
(DNA different)
1.) Separation – portion of the species becomes
isolated (newly formed canyon, mountain range,
river changing, storms) Example: Darwin’s finches
2.) Adaptation – when a single population becomes
divided, the groups may evolve separately due to
differences in the environment and may form
separate species due to natural selection.
3.) Division – over a very LONG period of time
(thousands or millions of years) the two
populations may become so different that they can
no longer interbreed – two different species!)