Download The Modern Synthesis: Evolution and Genetics Charles Darwin

Homework Questions
• PG. 287
Q3: Explain why harmful mutations do not
accumulate over time and cause harm to
populations.
ANSWER:
Harmful mutations cause harm to the individual
and evolution will select against individuals with
harmful mutations. These individuals will not
breed with others, causing the harmful mutation
to disappear from the population.
Homework Questions
• PG. 287
Q9: How do the genetic diversity of a population and
mutation rates limit the ability of breeders to create
organisms with desired traits?
ANSWER:
Hint: Think of the blue rose.
Breeders can only work with the genetic diversity that is
already present in the organisms population. If a trait does
not exist in an organisms genome, a breeder cannot just
create that mutation. Mutations are random and rare. This
means that beneficial mutations are unlikely to happen.
Homework Questions
• PG. 319
Q28: What is artifical selection, and why is it called
artificial?
ANSWER:
Artificial selection is directed breeding in which
individuals that exhibit a particular trait are
chosen as parents of the next generation. It’s
called artificial because it is controlled by human
choice, not by nature.
The Modern Synthesis:
Evolution and Genetics
Charles Darwin
- Born in Shrewsbury, England on
February 12, 1809
- Born into a wealthy family as the
5th of 6 children
- Grandfather, Erasmus Darwin, had
proposed that all life came from a
single organism, “the Great First
Cause”
- Darwin was encouraged to become
a doctor, but was fascinated with the
natural world
The Voyage of the Beagle
• December 27, 1831, he joins the HMS Beagle as a naturalist
on a five year voyage
• The ship’s mission was to map the coast of South America for
Britain
• As a naturalist, Darwin was to observe and collect specimens
How did he begin to craft
his theory of evolution?
Observations in South America
• In Argentina, Darwin
uncovered fossils of the
Megatherium and Glyptodon
• These fossils looked like giant
sloths and armadillos
• The fossils were found in the
same geological range as these
modern animals
• Fossils of marine organisms
also found in the Andes
Mountains
Observations in the Galapagos
Islands
• Island chain 1000 km west of Ecuador
• Discovered many new species with many similarities to species
found on South America
• No native amphibians or large land mammals
– why?
Observations in the Galapagos
Islands
• Marine Iguana:
– Closely resembles
iguanas from the
South American
Mainland
– Is the only known
lizard able to dive
and forage in
water
Observations in the Galapagos
Islands
• Giant land tortoises
– At least five unique
species were found on
different islands
Darwin’s Finches
• Darwin at first thought
they were one species
with variation
• 13 species with
distinct characteristics
• Their beaks show
variation in shape and
size
– Why?
Forming the Theory
• After leaving the Beagle in
1836, Darwin spent more than
20 years gathering evidence
on evolution
• He knew that his theories
would be controversial
• By the time he presented his
theory, Darwin was able to
not only explain that
evolution had happened, but
also how it occurred…mostly
On the Origin of Species
• By 1844 Darwin had
prepared an essay on his
theory of Evolution, but did
not publish it
• 1858 - received a letter from
Alfred Russell Wallace, who
had also concluded that
evolution must be true
• This pressure led Darwin to
publish his theory as On the
Origin of Species in 1859
Backlash
• Please read 294-295 and complete #1-4