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Darwin & Evolution by Natural Selection

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Warbler finch Cactus eater Tree finches Ground finches Insect eaters Seed eaters Bud eater Darwin & Evolution by Natural Selection Charles Darwin ___________________ ___________________ ___________________ How did creatures change over time? __________________

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darwin evolution by natural selection

Warbler

finch

Cactus

eater

Tree finches

Ground finches

Insect eaters

Seed eaters

Bud eater

Darwin & Evolution by Natural Selection

charles darwin
Charles Darwin
  • _________________________________________________________
    • How did creatures change over time?
    • __________________
  • _________________________________________________________
    • 1809-1882
    • British naturalist
voyage of the hms beagle
Voyage of the HMS Beagle
  • Invited to travel around the world
    • 1831-1836 (22 years old!)
    • makes many observations of nature
      • main mission of the Beagle was to chart South American coastline

Robert Fitzroy

voyage of the hms beagle4
Voyage of the HMS Beagle
  • Stopped in _____________________
    • 500 miles off coast of Ecuador
galapagos
Galapagos

Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland.

800 km west of Ecuador

darwin found many unique species
Darwin found…many unique species

Many of Darwin’s observations made him wonder… Why?

Darwin asked:

Why were these creatures found only on the Galapagos Islands?

darwin found clues in the fossils

present day Armadillos

ancient Armadillo

Darwin found…clues in the fossils

Darwin found:

_______________________________________________________________

Darwin asked:

Why should extinct armadillos & modern armadillos be found on same continent?

darwin found more fossils

present day Sloth

(extinct) Giant ground sloth

Darwin found… more fossils

Darwin found:

Evidence that creatures have changed over time

Darwin asked:

Why should extinct sloths & modern sloths be found on the same continent?

slide9

Darwin found:

Different shells on tortoises on different islands

Darwin asked:

Is there a relationship between the environment & what an animal looks like?

darwin found birds

Finch?

Sparrow?

Warbler?

Woodpecker?

Darwin found… birds

Darwin found:

Many different birds on the Galapagos Islands.

He thought he found very different kinds…

Finch?

Sparrow?

Warbler?

Woodpecker?

but darwin found a lot of finches

Finch?

Sparrow?

Warbler?

Woodpecker?

But Darwin found… a lot of finches

Darwin was amazed to find out:

All 14 species of birds were finches…

But there is only one species of finch on the mainland!

Large ground finch

Small ground finch

Darwin asked:

If the Galapagos finches came from the mainland, why are they so different now?

Warbler finch

Tree finch

the finches cinched it

Finch?

Sparrow?

Warbler?

Woodpecker?

The finches cinched it!

Darwin found:

The differences between species of finches were associated with the different food they ate.

Darwin said:

Ahaaaa! A flock of South American finches were stranded on the Galapagos…

Darwin said:

  • ___________________
  • ______________________________________
  • ___________________
  • ___________________
  • ___________________

Large ground finch

Big seed eater

Small seed eater

Small ground finch

Insect eater

Warbler finch

Leaf & bud eater

Tree finch

relationship between species beak food
Relationship between species (beak) & food

_____________________radiate out to fill different niches

darwin s finches
Darwin’s finches
  • Darwin’s conclusions
    • ___________________________________
      • differences in the original flock
      • adaptations to foods available on islands
    • ___________________________________
      • over many generations, the finches were selected for specific beaks & behaviors
    • ___________________________________
      • accumulation of winning traits:beaks & behaviors
    • ___________________________________
from 1 species to 14 species

Warbler finch

Cactus finch

Woodpecker finch

Sharp-beaked finch

Small insectivorous

tree finch

Small ground

finch

Warbler

finch

Large

insectivorous

tree finch

Cactus

eater

Medium

ground finch

Tree finches

Ground finches

Insect eaters

Seed eaters

Large ground

finch

Vegetarian

tree finch

Bud eater

From 1 species to 14 species…

variation

selection

heredity

earlier ideas on evolution
Earlier ideas on Evolution
  • LaMarck
    • creatures developed traits during their lifetime
    • give those traits to their offspring
    • example
      • in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring
darwin s view of evolution
Darwin’s view of Evolution
  • Darwin
    • giraffes that already have long necks survive better
    • leave more offspring who inherit their long necks
      • _______________
      • _______________
      • _______________
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