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Transcript
Timeline of Darwin’s life
 Born 1809
 Study (Edinburgh and Cambridge)
1825-1831
 Voyage of the Beagle 1831-1836
 Retired to Down 1842
 The Origin of Species 1859
 Died 1882
Not just an Evolutionist
 Not even a biologist to start with
 Collected beetles for fun
 Studied geology more seriously
 Considered himself a geologist throughout
the Beagle voyage and for some time after
 Famous for working out how coral atolls are
formed
An atoll is a ring-shaped coral reef, island, or series of islets.
An atoll surrounds a body of water called a lagoon. Sometimes, atolls and
lagoons protect a central island. Channels between islets connect a lagoon
to the open ocean or sea.
His books (not just on evolution)
 Beagle voyage
 Coral reefs
 Volcanic islands
 Geology of South
America
 Barnacles
 Species
 Man
•
•
•
•
Emotions
Climbing plants
Domestication
Cross and self
fertilization
• Orchids
• Worms
• Autobiography
Contributor’s to Darwin’s
thinking included:
Charles Lyell- Uniformitarianism
is the assumption that the natural
processes operating in the past are
the same as those that can be
observed operating in the present.
Georges Cuvier –
species extinction (1769-1832)
(1797-1875)
More people that contrubutored to
Darwin’s ideas.
 Thomas Malthus- struggle for existence
1766-1834
 Jean Baptisite de Lamarck- evolution
by acquired characteristics
1744-1829
Alfred Russell Wallace
 Thought of natural selection at the same time as
Darwin (1959)
 Wrote to Darwin, collaborated with Darwin on
solidifying the theory of evolution through natural
selection.
 Darwin had been working on book
 Published a “letter” jointly
 Wallace didn’t put in the years of data that Darwin did.
 Darwin published The Origin of Species without
Wallace
Darwin was Miscredited
 Died famous for evolution (which was not
his idea)
 Natural selection was his big idea--not
widely accepted, even among his supporters
 Darwin remained convinced
 Only 40-50 years later did scientists
appreciate his foresight.
Charles Darwin’s Ideas
 Naturalist on the HMS Beagle, Five year
journey
 Visits the Galapagos Islands
 He studied many organisms that were
unique to the islands, but similar to
elsewhere.
 After 22 years he proposed the process of
natural selection.
The Voyage of the Beagle
Darwin’s Finches
Galapagos Islands
 500-600 miles west off the coast of Ecuador
 Located directly on the equator
 Cold ocean coming from the south and warm ocean
current coming from the north meet at the islands
Galapagos Islands
• Islands are of volcanic
origin (much like the
Hawaiian islands)
 The oldest islands are
thought to be 5-10
million years old.
(much younger than
South America)
 Started as a “blank
slate.”
Joining the Beagle Voyage
 Not paid for 5 years on Beagle.
 Actually, he had to pay!
 Was the “Naturalist”
 Was lucky to get on
 Replaced someone who was shot in a duel
 his father opposed him going
 Mainly asked because of his class, to keep Captain
Fitzroy company
 It was the making of him
Galapagos, 1835
 Portrayed as a “Eureka” experience.
 Did not recognize significance until
back in England, 1837.
 Worked out theory much later.
 First inkling of natural selection in
1838.
 Tortoises & finches were key evidence
How did living things get to the
islands?
Remember they have to survive a
500 mile journey.
Rafting on debris or chunks of
land.
Birds may fly or be blown out in a
storm.
How would you survive in this
environment?
Galapagos Islands
Marine Iguana
• Have been thought to evolve from an ancestor
similar to what we know as a green iguana.
Marine Iguana
 Live by swimming in
the ocean and
scrapping algae off
rocks.
Only known
iguana that swims.
Marine Iguana Characteristics
 Flat Nose – Why?
 To scrape algae off rocks.
Marine Iguana Characteristics
 Long, flat tail
 Allows it to swim in the
ocean
 Big claws
 Allows it to hold onto
rocks while feeding
Marine Iguana Characteristics
 White stuff on back –
What is it?
 Salt – Salt glands in
nose– eats salty foods
and the glands allow it to
sneeze the salt out
 Black Color – Why?
 Allows it to warm up
after being in the cold
ocean
Land Iguana
• Have been thought to evolve from an ancestor
similar to what we know as a green iguana.
Land Iguana
 Lives on the land
 Is an Herbivore, eating mostly the fruit and pads of
cactus
Land Iguana Characteristics
 Bigger jaw/mouth than
the marine iguana –
WHY?
 Allows it to eat cactus
 Lighter coloring –WHY?
 Doesn’t heat up as fast.
Land Iguana Characteristics
 Neck flap (gular sack)





WHY?
Acts as a cooling system,
allows heat to escape body
Short, stubby legs – Why?
Allows it to support it’s big
weight
Bigger Body – WHY?
Resists heating up in the
desert sun
SOMETHING TO THINK ABOUT
Why did the land iguana and
marine iguana evolve so
differently from one another?
Galapagos Tortoise
Galapagos Tortoise
 Have been thought to evolve from an ancestor similar
to our desert tortoise.
Galapagos Tortoise Characteristics
 Live around 150 years
 There were around
250,000 around Darwin’s
time.
 Numbers have declined
to 15,000 or less.
 Key source of meat for
pirates and explorers.
Continued
 High shell at neck – Why?
 Allows it to stretch to reach food.
 Bigger body size – Why?
 Takes longer for an organism to warm
up in the hot desert sun.
Plants Evolve Too!
Swallow-tail Gull
 Flies and feeds at night
Swallow-tail Gull Characteristics
 Dark, Black coloring – WHY?
 Allows it to fly at night




without being spotted by
Frigate Bird
Red Ring around the eye –
WHY?
Red eye ring is thought to
attract more light to allow
bird to see at night.
White spot on beak – WHY?
When feeding at night chicks
can peck on the white spot to
tell the mother where they
are.
Mockingbird
 Mockingbirds will peck
at the iguanas, tortoises,
and other birds and
drink their blood during
hard times when water is
scarce.
 This is an example of a
behavioral adaptation.
How have humans impacted the
islands?
 Introduced Exotic Species
 Pigs, dogs, cats
 Invasive species of plants
 Tourism
 Many people travel to the islands
 While the islands are mostly national parks and quite
regulated, they have to deal with the conservation problems
that humans yachts and trash bring to the islands.
 Increase in Population
 People are moving to the islands looking for work
 The increase in tourism brings the need for more workers
 This puts more pressure on the natural resources of the islands
Natural Selection
 A mechanism for change in populations.
Natural Selection
1. In nature, organisms
produce more
offspring than can
survive.
2. In any population,
individuals have
variations.
3. Individuals with
certain useful
variations survive in
their environment,
passing those
variations to the next
generation. “Survival
of the Fittest”
4. Over time, offspring
with certain variations
make up most of the
population and may
look entirely different
from their ancestors.
Peppered Moths
 Online Example