Download Charles Darwin - Warren County Schools

• Evolution: gradual change over time
– Gradual Change—small changes along the
way
– Over Time—doesn’t happen over night
Charles Darwin
Charles Darwin
• The Author of the On the Origin of Species
• The most notable evolution theorist of our
time
• Known for his famous voyage on “The
Beagle”
• Arrived at the Galapagos Islands on
September 15th, 1835
• 5 week stay – was on land 19 days
collecting & observing
In 1831, the young naturalist Charles Darwin set
off on a five-year sail around the world that
would profoundly change not just his life, but the
course of science as well. Commissioned to
collect samples of flora and fauna from the HMS
Beagle’s ports of call, Darwin left England firmly
believing, like everyone else, that God had
created every living thing on Earth exactly as it
appeared. His specimens told him otherwise,
however, and when the Beagle docked in
England, core tenets of the theory of evolution
had been shaped. Yet it would be 20 years
before he would make his ideas public; Darwin
feared that disclosing his radical views would be
the equivalent of committing career suicide and
was moved to publish only when another
scientist independently arrived at the same
conclusions as he. That event sparked a debate
that continues to this day.
Charles Darwin
• In 1831 he sailed to
the Galapagos
Islands in the HMS
Beagle
• He left England on
this voyage at 22 yrs.
Old
• He published his
theory of evolution 30
years later
The HMS Beagle
Darwin Left England in 1831
Darwin returned 5 years later in 1836
13 major islands, 6 minor islands, & 40 smaller rock formations & reefs
– 3000 square miles of land covering 17,000 miles of ocean located
600 miles west of Ecuador
Galapagos Islands
• Volcanic in origin – oldest are 325 million
years old
• Hot spot formation theory
• Still active volcanoes
• Never connected to the mainlands
Galapagos Islands
• Until their discovery in 1535, life here
evolved in isolation producing strange &
marvelous species
• 8 Habitats to accommodate a large variety
of species:
Open sea
Rocky shores
Mangrove coasts
Transitional zone
Rocky islets
Sandy beaches
Arid zone
Highlands
Bartolome Island – arid zone
North Seymour Island – transition zone
Rocky Islets
Black Sand Beach
Flamingos on the mangrove coasts
Rocky shores
Red Sand Beach
Highlands
View atop a inactive volcano
Darwin and the Galapagos
• He focused
evolutionary
principles on
populations
• Why were there so
many different plants
and animals found in
the Galapagos?
Animals of Galapagos
Galapagos Penguins
Land Iguana
Pink Flamingo
Frigate Bird
Galapagos Tortoise
Tortoise nesting video
There are currently only 11 subspecies
Left in the world today.
Lonesome George
• George is a Pinta
Island Tortoise
• He is the very LAST
one known in
existence
• There is a reward of
$10,000 offered by
the zoo association if
a female is found
The Boobys
Blue Footed booby
Red footed booby
Masked booby
Blue Footed Booby
• http://www.youtube.co
m/watch?v=oYmzdvM
oUUA
• Mating Dance
Waved Albatross
Animals of the Galapagos
Sea Lions
Marine iguana
Sally Lightfoot Crabs
Darwin’s Ideas
Darwin at 31
• Evolution is due to
genetic variation and
natural selection on
heritable characters
• Recognized natural
selection as the
mechanism in 1838
Sketch of genetic line
Evidence used in Darwin’s Natural Selection Theory
• 1. Biogeography: Distinct features of cosmopolitan
species and the presence of endemic species (Darwin's
finches: of the 14 finch species of the Galapagos islands,
13 are endemic)
• 2. Morphology and embryology: Homologous structures
among related species; similarities in the embryos of
related species
– Homologous Structure-features that are similar in structure but
appear in different organisms and have different functions; offers
support for common ancestor
– Analogous Structure-perform a similar function but are not
similar in orgin
• 3. Palaeontology: Gradual change in the fossil record,
evident extinctions
• 4. Taxonomy and systematics: Morphological similarities
among related taxa
Natural Selection
• Darwin is credited with the theory of
evolution by natural selection.
• Natural selection is that the strongest
survive and propagate and therefore
increase the strength of the species
Darwin Finches
• Once on the islands,
various species
established
themselves and
determined territories
• Evolution then set in
and many unique
species, such as
Darwin’s finches
resulted
Speciation
• Formation of a new species
• As new species evolve, populations become
reproductively isolated from each other (they
cannot interbreed) called reproductive isolation
• Behavioral isolation occurs when 2 populations
are capable of interbreeding but have
differences in courtship rituals & are then not
attracted to each other
• Geographic isolation – 2 populations are
separated by geographic barriers such as rivers,
or mountains
• Temporal Isolation occurs when 2 organisms
reproduce at different times
Darwin’s Finches and Natural
Selection
• The finches probably
descended from one
type of ancestor and
due to isolation and
through chance,
different climates,
natural forces, and
food type, evolved
into the 13 different
types of finches
Finch Beaks
• Finch’s beaks vary based on their diet
– some eat fruit and seeds
– other insects
– some can even suck the blood from marine
birds on the islands when they can't find their
usual food.
– Certain varieties of finch clean the ticks from
the shells of the giant tortoises.
Peppered Moths
http://www.biologycorner.com/worksheets/pepperedmoth.html
Natural Variation
• Some cows give more milk
• Some plants bear larger fruit
• Some humans are taller than others
Much of this variation is inherited & passed on to
the next generation
Humans may take advantage of this variation by
breeding certain organisms together with the
desired trait (artificial selection)
Natural selection • Something like artificial selection occurs in
nature – called natural selection
• However, the traits being selected contribute to
an organism’s fitness without human control
• There is always a struggle for existence & the
“fitness” of an organism depends on its survival
& its reproductive success (“Survival of the
Fittest”)
Example:
faster = better predator
camouflage
behavior
better protection from extremes
Adaptation
• These changes increase the chance of
survival & thus the traits that allow for
survival are passed on the next generation