Title: OBJECTIVES
1OBJECTIVESÂ Â Â Â Â
- The Historical Context for Evolutionary Theory
- Explain the mechanism for evolutionary change
proposed by Charles Darwin in On the Origin of
Species. - Define evolution and adaptation.
- Compare and contrast Aristotles scala naturae to
Carolus Linnaeus classification scheme. - Describe the theories of catastrophism,
gradualism, and uniformitarianism - Explain the mechanism for evolutionary change
proposed by Jean-Baptiste de Lamarck. Explain why
modern biology has rejected Lamarcks theories.  Â
2The Darwinian Revolution
- Describe how Darwins observations on the voyage
of the HMS Beagle led him to formulate and
support his theory of evolution. - Explain how the principle of gradualism and
Charles Lyells theory of uniformitarianism
influenced Darwins ideas about evolution. - Explain what Darwin meant by descent with
modification. - Explain what evidence convinced Darwin that
species change over time. - Explain how Linnaeus classification scheme fit
Darwins theory of evolution by natural
selection. - Describe the three inferences Darwin made from
his observations that led him to propose natural
selection as a mechanism for evolutionary change. - Explain how an essay by the Rev. Thomas Malthus
influenced Charles Darwin. - Distinguish between artificial selection and
natural selection. - Explain why an individual organism cannot evolve.
- Describe the experiments that supported Reznick
and Endlers hypothesis that differences in
life-history traits between guppy populations are
due to selective pressure based on predation. - Explain how the existence of homologous and
vestigial structures can be explained by Darwins
theory of natural selection. - Explain how evidence from biogeography supports
the theory of evolution by natural selection. - Explain the problem with the statement that
Darwinism is just a theory. Distinguish between
the scientific and colloquial use of the word
theory.
3CHAPTER 22DESCENT WITH MODIFICATION
4What is evolution?
- Process that has transformed life on Earth from
its earliest forms to the enormous diversity of
today - Most convincing case for evolution was published
by Darwin in 1859 On the Origin of Species by
Means of Natural Selection
5Historical Context of Darwins Life and Ideas
6Western Culture Resisted Evolution
- Plato Idealism Prefect and perceived worlds
- Aristotle Questioned Platos dualism but
believed species fixed and prevailed for 2000
years - Range from simple to complex (scala naturae)
- Judeo Christian view
- Carolus Linnaeus Father of taxonomy (naming and
classifying organisms) but believed species were
permanent creations only to support religious
beliefs
7Cuvier, Fossils, and Catastrophism
- Fossils Relics or impressions of organisms from
the past, usually preserved in rock - Fossil record provides evidence that earth has
had a succession of flora and fauna - Usually found in sedimentary rock (layers upon
layers of soil, sand, mud, etc.)
8Cuvier Father of paleontology (study of fossils)
- Realized lifes history was recorded in
fossil-containing strata and documented
succession of fossil species in Paris Basin - Each stratum characterized by a unique set of
fossil species oldest stratum most dissimilar
to modern life forms - From stratum to stratum, new species appeared and
others disappeared
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10Catastrophism Theory that major changes in the
Earths crust are the result of catastrophic
events rather than from gradual processes of
change
- Periodic localized catastrophes resulted in mass
extinctions - Following extinctions, region becomes repopulated
by foreign species immigrating from other areas
11Geological theories
- Gradualism James Hutton profound change is
the product of slow, continuous processes
12- Uniformitarianism Theory that geological
processes are uniform and have operated from the
origin of Earth to present (Charles Lyell)
13Lamark
- Proposed Mechanism By Which Organisms Evolved
- Use and disuse Those body organs used
extensively to cope with the environment become
larger and stronger while those not used
deteriorate - Inheritance of acquired characteristics
modifications an organism acquired during its
lifetime could be passed along to its offspring
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15Voyage of the Beagle
- While ships mission was to chart South America
(SA) coastline, Darwin made observations - SA flora and fauna were distinct from European
flora and fauna - Temperate species closer to tropical species than
temperate species in Europe - SA fossils were distinctly SA
- Most animal species on Galapagos are unique to
those islands, but resemble species living on SA
coastline
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18Origin of Species
- Descent with Modification (evolution)
- Unity in life with all organisms related through
descent from ancestral population - Diverse modifications (adaptations) accumulated
over millions of years as descendants moved into
various habitats
19Darwins view of Evolution Branches at the end
demonstrate the diversity of the species
20Natural Selection and Adaptations
- Observation 1 All species overproduce
Flowers or Seeds
21- Observation 2 Most populations are normally
stable except for seasonal fluctuations - Observation 3 Natural resources are limited
- Inference 1 Struggle for existence allows for
survival of only a fraction of offspring - Food, water, and space
22- Observation 4 Variation exists in population
- No spot on the ladybugs below is the same as
another
23- Observation 5 Much of this variation is
heritable - Inference 2 Those individuals best fit to
survive will produce more offspring than those
less fit to survive - Inference 3 Unequal ability of individuals to
survive and reproduce will lead to a gradual
change in populations, with favorable
characteristics accumulating over generations
24- Gradualism Evolution occurs by a gradual
accumulation of small changes and mechanism of
modification is natural selection - Populations Group of interbreeding individuals
belonging to a particular species and geographic
location are the smallest unit that can evolve
25Evidence
- Biogeography Geographical distribution of
species - Islands have many endemic species which are
closely related to species on the nearest
mainland or neighboring island
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27The Fossil Record
- Many transition fossils have been found that link
ancestral species to modern forms - Fossil record supports other kinds of evidence
about phylogenetic tree - Prokaryotes are placed as ancestors of all life
by evidence from cell biology, biochemistry, and
molecular biology - Fossil evidence shows chronological appearance of
vertebrates fishes, amphibians, reptiles, then
birds, and mammals
28Comparative Anatomy Anatomical similarities
among species grouped in the same taxonomic
category as a reflection of common descent
- Homologous structures similar because of common
ancestry
29Vestigial organs rudimentary structures of
marginal or no use to an organism
- In the early 1900s these structures were
considered useless. Today there is at least 1
known function for each.
30- Comparative Embryology Closely related
organisms go through similar stages in their
embryonic development gill slits develop into
eustachian tubes in humans
31Molecular Biology An organisms hereditary
background is reflected in its genes and their
protein products
- Sibling similarity
- Two closely related species should share a great
proportion of their genes and proteins