Download Evolutionary Theory

Evolution and Systematics
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EARLY THEORIES OF EVOLUTION
DARWIN, WALLACE, & THE ORIGIN
DARWIN’S THEORIES OF EVOLUTION
WHAT EVOLUTION IS NOT
MODERN SYNTHESIS
BIOGEOGRAPHY
SCHOOLS OF SYSTEMATICS
Early theories of natural history and classification
treated living things as immutable and were
essentialistic. From the end of the 18th century and
the early part of the 19th century the study of the
diversity of life developed into four forms:
• Progress by catastrophes (e.g. Cuvier)
• Progressive transmutation (e.g. Lamarck)
• Natural Theology (e.g. Paley)
• Naturphilosophie (e.g. Goethe)
Jean-Baptiste Pierre Antoine de
Monet, Chevalier de Lamarck
• Though others had suggested
it, Lamarck gave the first clear
theory of the mutability
(transmutation) of species
• Came to this view after trying
to organize the invertebrate
collection in the Natural
History Museum in Paris
• Theory of two parts:
– A generating force pushed living
things up the scala naturae
– Acquired characters allowed
them to become adapted to
local conditions
1744-1829, France
Natural Theology
• Teleology inserted into natural
history in the tradition of
Thomas Aquinas
• This evolved into the search
for the purpose intended by
the creator
• Mainly British and American
proponents (~1750-1850)
• William Paley (1743-1805,
Britain) most well known for
his teleological argument for
the existence of God
• Best known is his watchmaker
argument
Naturphilosophie
• German movement in natural history
begun by Johann Christoph Friedrich
von Schiller (1759-1805, Germany)
• Search for the ur-plant and the uranimal
• Study the parts but interpret them as
in a holistic way (e.g. plant parts all
modifications of the leaf and skeletal
elements all modifications of the
vertebra –Goethe)
• Most famous of the Naturphilosphen
was Johann Wolfgang von Goethe
(1749-1832, Germany) work on light
and flowers
• Fit well with embryology and the idea
that species could change toward an
Monument of Goethe(L) and Schiller(R)
ideal
in Weimar
The rise of paleontology, global explorations,
and uniformitarianism suggested a gradually
changing world versus the periodic catastrophes
of Cuvier. Still Charles Lyell accepted the
immutability of species.
Charles Robert Darwin
• Born 12 February 1809,
Britain
• Unmotivated student with
poor aptitude for languages
• Sent to Edinburgh to study
medicine with his older
brother Erasmus
• Entered Cambridge and
studied under Adam
Sedgwick (1785-1873) and
John Stephens Henslow
(1796-1861)
• Avid beetle collector
Second Voyage of the H.M.S. Beagle
• Introduced to ad for a naturalist by Henslow
• Robert Fitzroy (1805-1865)
• 27 December 1831-2 October 1836
Returned to England a Celebrity
Among Scientists
• Initially lived in London and
Cambridge
• Became active in scientific societies
there
• Wrote his Journal for publication,
sold very well unlike Fitzroy’s
journal
• Within a year, Darwin was
speculating about the mutability of
species
• He married his cousin, Emma
Wedgwood
• Moved to the village of Downe
Malthusian Crisis
Thomas Robert Malthus (1766-1834, Britain)
From Darwin’s Autobiography
"In October 1838, fifteen months after I had begun
my systematic inquiry, I happened to read for
amusement Malthus on Population, and being
prepared to appreciate the struggle for existence
which everywhere goes on, from long-continued
observation of the habits of animals and plants, it
at once struck me that under these circumstances
favourable variations would tend to be preserved,
and unfavourable ones to be destroyed. The result
would be the formation of a new species.“
Breeding and Domestication
All pigeon and dog
breeds must have
come from just one
and differences
through selective
breeding or artificial
selection
Darwin found his mechanism for change:
Natural selection
Variation
Struggle for existence
Darwin spent the next 20 years gathering
evidence from:
– Domestication
– Examples of Variation
– Classification
– Complex Organs
– Rudimentary Organs
– Instinct
– Hybrids
– Geological Record
– Succession of Life through Geologic Time
– Geographical Distribution
– Embryology
Robert Chambers & The Vestiges of Creation
• Published anonymously
1844
• Argued for a progressive
evolution of life and the
cosmos
• Similar to Lamarck and
Naturphilosophie
• The strong reaction caused
Darwin to set aside his
developing manuscript on
the Species Book
1802-1871, publisher and naturalist,
Britain (Scotland)
Naturalists inspired to explore (a short list)
• Henry Walter Bates
(1825-1892)
• Alfred Russel Wallace
(1823-1913)
• Joseph Dalton Hooker
(1817-1911)
• Thomas Henry Huxley
(1825-1895)
Wallace in Amazonia
• 1848 left England with Bates
• Collected near Belem and then they separated
• Wallace spent 4 years on the Rio Negro & returned in
1852
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Wallace in Moluccas
1854 to Moluccas (the Spice Islands)
Cataloged >126,000 specimens
Noted differences in island taxa
Returned in 1862
Letter from Ternate
• In malarial fever, he mulled over why so many
species after having read Malthus.
• He had already published the Sarawak Law, an
exploration of why related species occupy
nearby but not identical spaces
• Sent letter with a manuscript to Charles Lyell
via a naturalist whom he had met briefly
before traveling to the Spice Islands and with
whom he had corresponded, Charles Darwin
The Origin, Published 1859
• Living things have changed over time
– The fact of evolution
• Common descent of all living things
– The unifying principle of biology
• Multiplication of species
– Theory of the origin of biological diversity
• Gradualism
– Applies theory of uniformitarianism to the history of life
• Natural selection
– Theory of change in species over time in response to local
conditions
Living things have changed over time
The fact of evolution
Common descent of all living things
The unifying principle of biology
• The genealogy of all living organisms can be traced
back to a single common ancestor.
Theobald, Douglas L. "29+
Evidences Macroevolution: The
Scientific Case for Common
Descent." The Talk.Origins
Archive. Vers. 2.83. 2004. 12 Jan,
2004<http://www.talkorigins.org
/faqs/comdesc/>
Multiplication of species
Origin of biological diversity
Sato et al. 1999. Phylogeny of
Darwin's finches as revealed by
mtDNA sequences. Proc Natl
Acad Sci U S A. 96 (9): 5101–
5106
Gradualism
Applies theory of uniformitarianism to the
history of life
• Charles Lyell- changes in history of the Earth
occurred gradually
• Influenced Darwin’s thinking on how changes
in the history of life occurred
• Problem with Lord Kelvin’s estimate for the
age of the earth (~100,000,000 years)
Natural selection
Theory of change in species over time in
response to local conditions
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Organisms exhibit variation in particular traits
There is a heritable basis to this variation
Organisms produce more offspring than can survive
Organisms with favorable traits produce more
offspring than those with unfavorable traits
What Evolution Is NOT
• The origin of life
• Anthropocentrism
• Progressionism
• Purpose of life (teleology)
Darwin’s Books Following Origin
1862: On the various contrivances by which British and foreign orchids are
fertilised by insects
1865: The Movements and Habits of Climbing Plants (Linnean Society paper,
published in book form in 1875)
1868: The Variation of Animals and Plants under Domestication
1871: The Descent of Man, and Selection in Relation to Sex
1872: The Expression of Emotions in Man and Animals
1875: Insectivorous Plants
1876: The Effects of Cross and Self Fertilisation in the Vegetable Kingdom
1877: The Different Forms of Flowers on Plants of the Same Species
1879: "Preface and 'a preliminary notice'" in Ernst Krause's Erasmus Darwin
1880: The Power of Movement in Plants
1881: The Formation of Vegetable Mould through the Action of Worms
Abuses of evolutionary theory
• Fraud
– Piltdown man
• Political movements
– Social Darwinism
– Lysenkoism
– Creation science
De Vries Theory of Mutationism
• Though Darwin convinced the scientific
community of change over time, few
supported natural selection
• Mutations gave rise to jumps (hopeful
monsters)
• Early period of the Mendelian renaissance
seemed to support mutationism
Modern Evolutionary Synthesis
• Mutations -> variation
• Natural selection operates on the
variation
• Developed 1936-1947
• Julian Sorell Huxley (1887-1975)
• Others: Ronald Aylmer Fisher (18901962); Theodosius Grygorovych
Dobzhansky (1900-1975); John Burdon
Sanderson Haldane (1892-1964); Ernst
Walter Mayr (1904-2005); George
Gaylord Simpson (1902-1984); George
Ledyard Stebbins (1906-2000), et al.
Julian Huxley
Modes of Speciation
Molecular clocks
• Theory after Emile Zukerkandl
(1922- Austria & USA) and Linus
Pauling (1901-1994, USA) in
1962
• Motoo Kimura (1924-1994,
Japan & USA) developed neutral
theory of molecular biology
• Assumption- change in
molecules or genomes over
geological time is constant
• “Molecular clocks” can be used
to determine evolutionary
relationships among taxa
• Reliability depends on constancy
of molecular change!
– Non-coding regions vs genes
subject to selection
Wallace and Biogeography
The Geographical Distribution of
Animals (1876)
Island Biogeography by Wilson and
MacArthur
Theory that explores the relationship between
evolution and extinction relative to area
Edward Osborne Wilson (1929), USA
Robert Helmut MacArthur (1930-1972), USA
Major Implications for Landscape
Ecology and Wildlife Management
Schools of Evolutionary Reconstruction
• Evolutionary Systematics (generate
phylogenetic trees)
• Numerical Systematics (Phenetics, generate
phenograms)
• Phylogenetic Systematics (Cladistics, generate
cladograms)
Rise of Cladistics
• Founded by Willi Hennig
• Difference between primitive
and derived characters very
important
• This system is very powerful
when coupled with molecular
data
1913, Germany
Character-Taxon
Cladogram
Interpretation of Cladogram
Biodiversity