Transcript Vertebrates

It is interesting to contemplate a tangled bank, clothed with
many plants of many kinds, with birds singing on the bushes,
with various insects flitting about, and with worms crawling
through the damp earth, and to reflect that these elaborately
constructed forms, so different from each other, and dependent
upon each other in so complex a manner, have all been
produced by laws acting around us. . . .
There is grandeur in this view of life, with its several powers,
having been originally breathed by the Creator into a few
forms or into one; and that, whilst this planet has gone cycling
on according to the fixed law of gravity, from so simple a
beginning endless forms most beautiful and most wonderful
have been, and are being evolved.
Parts of last paragraph of Charles Darwin’s, “Origin of Species by Means of Natural
Selection or the Preservation of Favored Races in the Struggle for Life” Sixth
Edition, January 1872
Voyage of
the Beagle
12 shirts
1 carpet bag
1 pair slippers
1 pair of light walking shoes
1 microscope (a single lens model by Bancks & Son,
London)
1 geological compass
1 plain compass
2 pistols (with spare parts)
1 rifle (with spare parts)
1 telescope
1 pencil case
1 geological hammer
5 simisometers
3 mountain barometers
1 clinometer
1 camera obscura
1 hygrometer (belonged to FitzRoy)
1 taxidermy book
2-3 Spanish language books
14 other books, including Humboldt's "Personal
Narrative" and Lyell's "Principles of Geology Vol. 1"
1 coin purse (Fanny Owen's gift)
1 pin with a lock of Sarah Owen's hair (Fanny's sister)
Voyage of
the Beagle
© AboutDarwin.com
(good link)
Fig 22.5
Voyage of the
Beagle 18311836
Home again
Down House, in Downe,
Kentshire, England, south
of London. Darwin’s home
from 1842 to 1882
Sand Walk, site of much of
Darwin’s contemplation
Alfred Wallace
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British naturalist
1858 - letter from
West Indies with
article to review for
Darwin to forward to
geologist, Lyell
Proposed theory of
evolution identical to
the one Darwin was
working on
Darwin Publishes
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“Origin of Species”
presented later in 1858
(32 years after then
end of his voyage) and
published 1st in 1859
Both men jointly
presented their ideas to
the London
Philospophical Society
The Origin of Species
• Evolution is the explanation for life’s unity
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and diversity
Natural selection is the mechanism
• What evidence did Darwin draw on?
Reproductive potential
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Species have great
potential powers of
reproduction
Populations would
increase exponentially
if all individuals
survived and
reproduced
Populations are stable
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But populations tend
to remain stable over
time
Except for seasonal
fluctuations
Moose population on island in
Lake Superior
Limited resources
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Environmental
resources are limited
Discussion in Malthus,
“Essay on the Principle
of Population” helped
clarify this
Lucky Lynx and its 1 hare
Observation 4
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Individuals in
a population
vary
extensively
Variation is inherited
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Much of this variation
is heritable
However, Darwin did
not know the
mechanism
Adaptation
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Organisms are
adapted to their
environments
A floral mantid on a flower. Please
look at the entire figure in the text
Artificial selection
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Of plants and
animals by humans
Vegetables selected by humans from wild “kole”
Other evidence
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Homologous
structures
Forearm bones in mammals
Biogeography
Adaptive radiation of Australian marsupials
compared to similarities among other mammals
Fossils
Fossil Trilobites
Elephant evolution based on fossils
Charles Darwin’s Legacy
(a selection of his writing)
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Journal of Researches into the Natural History
and Geology of the countries visited during the
voyage round the world of H.M.S. Beagle
On the origin of species by means of natural
selection
On the various contrivances by which British and
foreign orchids are fertilised
The variation of animals and plants under
domestication
The descent of man and selection in relation to
sex
The expression of the emotions in man and
animals
The effects of cross and self fertilisation in the
vegetable kingdom
The formation of vegetable mould, through the
action of worms
John van Wyhe’s web site with links to
web copies of all of Charles Darwin’s writings
Darwins mechanism
• Natural selection
• Four conditions
* Populations of species vary in their characters
* Some of the aspects governing the characters
are heritable
* More offspring produced than can be supported
by resources
* Those best able to “cope” (= reach reproductive
age) leave the most offspring
Darwin’s mechanism
• Net result – “survival of the fittest”
* best adaptive characteristics survive
* least adaptive “perish”
* in next generation populations of the species
• What is needed?
* populations (individuals don’t evolve)
* environments
* time – lots of time