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Evolution
A fundamental theme in all of biology
Charles Darwin
(1809 - 1882)
British naturalist
Theological & ______ training
Father was a surgeon
1830’s: naturalist on the ______
Traveled around the globe
Observed and collected nature
Afterward, conducted ___________ with domestic
animals
In 1959, published: “On the origin of species by means
of ________________”
Said Natural Selection was the ________ of evolution
“Survival of the fittest”
Alfred Russel ______ also described natural selection
Darwin’s rationale for natural selection:
1) All species produce _______ offspring
High reproductive _________
2) Resources (food, shelter) are ________
Causes a ________ for survival
Intraspecific competition
3) Individuals of a population differ somewhat
Genetic variation
4) Individuals with “_______” traits compete better
Are more likely to contribute to next generation
Adaptation: a trait that increases _______
Increase __________ of:
Good health
Successful breeding
Passing adaptive traits to the next generation
Darwinian fitness:
Successful passing of ______ to next generation
Physical evidence for _____-evolution:
Gradual changes over ________ time
1) Fossils
Bones, shells, footprints, droppings, etc.
Occur in _______________ strata
Deeper = _______
Grand Canyon exposes strata >1 billion years old
Transitional fossils show gradual ______ over time
E.g., horse evolution:
55 - 45 mya
33 - 29 mya
mya = millions of years ago
17 - 11 mya
present
2) Comparative Anatomy
_________________ structures
Inherited from a _______ ancestor
E.g., forelimbs of all mammals have the same bones:
Human:
grasping
Cat:
pouncing
Whale:
swimming
Bat:
flying
Conclusion: the common ancestor of mammals had these bones
Vestigial structures
Size and function very _______
Results from ______ over time
E.g., tail (coccyx) in humans:
Hind limbs of certain snakes:
3) Embryological development
Similar organisms have similar __________ stages
E.g., early vertebrate embryos:
Become typical of their type at the ________ stage
4) Universality of the genetic code
Genetic code of all organisms is based on
the same 4 nucleotides
Suggests the first organism was a common
ancestor to all
Two types of evolution:
1) __________ evolution
One species becomes two (or more) over time
Usually results from geographic ____________
E.g., the Ratite (large, flightless) birds:
Southern continents were once joined
___ ancestral species occupied the whole area
After southern continents split up:
Ostrich
(Africa)
Rhea
(S. America)
Emu
(Australia)
2)____________ evolution
Parallel evolution of a similar adaptation
Not inherited from a common ancestor
E.g., fins of penguins and whales
Common ancestor of birds and whales was a ______
Resulted from adapting to similar ____________
Referred to as _________ structures