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Sylvia S. Mader
Immagini e
concetti
della biologia
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
A8 - Principles
of evolution
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Darwin’s journey
In 1831 Charles Darwin made a
journey around the world.
He observed that species change
from place to place and through time.
Charles Darwin (1809-1882)
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Darwin’s journey
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Darwin’s observations
Rheas living in South America
had the same adaptations to
desert as african ostriches.
Darwin's Rhea
Marine fossils in the rocks of the
mountains.
Earth’s strata contain fossils
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
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Darwin’s observations
Patagonia desert
Tropical rain forest
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Similar organisms living in the
Patagonia desert and in tropical
forests showed different
characteristics.
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Darwin’s observations
Galapagos iguanas had claws
and muzzle adapted to the
environment.
Marine Iguana
New species of finches on the
Galàpagos had different beaks in
relation to their feeding habits.
Woodpecker finch
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
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Darwin’s knowledges supporting
evolution
Charles Lyell (geologist)
Earth is old enough for evolution to have
resulted in the species seen today.
Georges Cuvier (paleontologist)
Catastrophes caused evolution to occur.
Jean-Baptiste de Lamarck (zoologist)
Inheritance of acquired traits is a
mechanism of evolution.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Artificial selection mimics natural
selection
Chinese cabbage
wild mustard
Brussels sprout
In agriculture humans select
and maintain specific traits
in certain populations.
Kohlrabi
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The natural selection
• Members of a population have inheritable
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variations
Stronger individuals are more likely to
reproduce
A population is able to produce more
offsprings than the environment can
support
There is always a struggle for survival
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The natural selection
Darwin observed natural selection in Galàpagos finches.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Studying the natural selection today
Scientists are observing variations in the beak of Medium
Ground Finch (Geospiza fortis) in relation with climate
changes at Galàpagos islands.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evolution
“A series of changes in a population over
time, due to an accumulation of inherited
differences”.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
Fossils provide records for the past.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
The fossil records indicate that life has progressed from
the simplest organisms to more complex ones.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
Some fossils (as Archaeopteryx lithographica) have
intermediate characteristics between two different groups
(i.e. birds and reptiles).
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
COMPARATIVE ANATOMY
Homologous structures are anatomically similar among
certain organisms and suggest that organisms have a
common descendent.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
COMPARATIVE ANATOMY
Some organisms have vestigial structures, memories
of functional structures in ancestors.
Vestigial structure
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
BIOGEOGRAPHY
Some plants and animals evolved in
particular locations.
Therefore similar environments, widely
separated, contain different organisms with
similar adaptations.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Evidences for evolution
Molecular evidences
The degree of similarity of
DNA (or amino acid) base
sequences shows a pattern of
relations between organisms.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012