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The Evolution Revolution: Why Darwin’s
Insights Matter Today
Spencer C.H. Barrett
Department of Ecology & Evolutionary
Biology, University of Toronto
adoption of herbicide
spraying
1
Darwin’s big idea and how it changed
biology and our understanding of the
world we live in
2
Theory of Evolution
•  The central unifying concept of biology
•  Affects many other areas of knowledge
•  One of the most influential concepts of
Western thought
3
Theory of evolution involved two
controversial ideas
•  Concept of a changing universe
replaced view of a static world
•  A phenomenon with no purpose
replaced view that the causes of all
phenomena had to have a purpose
“Nothing in biology makes
sense except in the light
of evolution”
Theodosius Dobzhansky
(1900-1975)
Fruit fly geneticist and founder
of the modern evolutionary
synthesis
Development of Darwin s ideas
on evolution - exploration
•  Darwin influenced by the botanist John S.
Henslow at Cambridge
•  Voyage on H.M.S. Beagle around the
world (1831-1836) as ship s naturalist
•  Made numerous observations and
collections of plants, animals & fossils
•  Returned to England and spent the rest
of his life in seclusion at Down House
developing his ideas, conducting
experiments and writing books (25 in all)
Development of Darwin s ideas
on evolution – gradualism
•  Darwin reads Lyell s book
Principles of Geology (1830)
•  Lyell argued that present day
geological processes can explain the
history of the earth – gradualism
•  The notion of a dynamic rather than
a static world emerged in Darwin s
thinking
Charles Lyell
(1797-1875)
Development of Darwin s ideas
on evolution – species vary
Variation patterns of
Galápagos mockingbirds
•  Darwin doubts fixity of species
(March, 1837)
•  There are 4 similar species
endemic to the islands
descended from a South
American mainland ancestor
Development of Darwin s ideas
on evolution - selection
Darwin reads Malthus (1798)
Essay on the Principle of
Population (Sept 1838)
I happened to read for amusement
Malthus on Population, and being well
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 would be destroyed.
Charles Darwin (1838)
Down House – Darwin s family home
(Kent, England)
Darwin lived at Down house from 1842-1882 and
conducted all his research and writing there
Darwin s
study
The Sandwalk – Darwin s thinking walk
View from Sandwalk of Darwin s glasshouse
and Down House
The Origin of Species
Two key components
•  All organisms have descended with
modification from common
ancestors = tree of life
•  The agent of modification is natural
selection operating on variation among
individuals = mechanism of evolution
Darwin s first evolutionary tree
The only figure in the
Origin was a tree
The affinities of all beings… have
sometimes been represented as a
great tree … and so by generation I
believe it has been with the great
tree of life
Darwin 1859
DNA sequence variation confirms Darwin’s hypothesis
of descent with modification and has enabled building of
evolutionary trees
DNA
sequencer
Why is molecular data relevant
to reconstructing the history of life?
•  All life is related through branching
descent
•  Common genetic code is evidence that all
life is related
•  Evolutionary relationships among species
are reflected in their DNA sequences
DNA sequencing is enabling rapid construction of
the tree of life – the Toronto connection
r
Wayne Maddison
UBC
Dave Maddison
Univ. of Arizona
•  Tree of life web project
provides 10,000 webpages
about biodiversity and
phylogenetic relationships
http://tolweb.org/tree
The Origin of Species
Two key components
•  All organisms have descended with
modification from common ancestors
•  The agent of modification is natural
selection operating on variation among
individuals
Jean-Baptiste de Lamarck
(1744 -1829)
•  First to use the term
evolution
•  Linear rather than
branching view of
evolution
•  First to provide a causal
mechanism –
The inheritance of
acquired characters
Lamarck s mechanism is wrong !
•  The giraffe s neck: Lamarck s example for the
inheritance of acquired characters
•  Progressive increase in neck during the life time
of an individual is passed on to offspring
Discovery of the correct mechanism
Darwin
Wallace
Charles Darwin & Alfred Russell Wallace co-discover
the chief mechanism of evolution
Today hundreds of studies demonstrating
natural selection
Requirements for natural selection
to work
•  Variation – variation among individuals
in a population
•  Heredity – progeny resemble their
parents more than unrelated individuals
•  Selection – some forms better at
surviving and breeding than others in a
given environment
All are widely accepted and known to be true !
Important assumptions about evolution
verified by scientific study
•  Organisms on earth have changed through time
•  The changes are gradual not instantaneous
•  Lineages split or branch by speciation resulting in
the generation of biodiversity
•  All species have common ancestors
•  Most evolutionary change results from natural
selection - the only process responsible for the
evolution of biodiversity and adaptation
Biodiversity and adaptation are therefore
products of evolution
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Orchid from Madagascar with long floral
tube pollinated by night-flying moth
with exceptionally long proboscis
•  Darwin predicted
the existence of
the moth
•  A century later it
was discovered
•  example of coadaptation
Pollen grains
Short 5
minute break
and questions
25
Contemporary Evolution
•  Evolution is not something that
happened in the past, as long as
life exists it never stops!
•  Today, contemporary evolution is
studied in diverse contexts both
basic and applied
•  Applied evolutionary biology
is a burgeoning discipline of
direct relevance to human
society
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Agriculture & fisheries
Medicine
Invasive species
Pollution
Global climate change
Conservation biology
Evolution in the lab –
experimental evolution
Lenski the founder of
experimental evolution –
20 yr. experiment with E. coli
> 40,000 generations
of evolution!
Informing understanding of anti-biotic
resistance and microbe evolution
Richard Lenski – Univ
of Michigan
Experimental evolution with E. coli
single strain
twelve populations propagated under
minimal glucose/citrate medium
42,000 generations in
serial culture
Experimental evolution with E. coli
•  all populations rapidly
increased in fitness
•  similar adaptations
across strains (e.g. larger
cell sizes, higher
maximal growth rates on
glucose)
•  parallel mutations at
same genes
Samples frozen at intervals allowing
relative fitness of different generations
to be compared
•  some unique
adaptations and distinct
genetic changes
Novel key innovation in single
strain after 33,000 generations!
beneficial mutation
(cit+)
Evolution in agricultural weeds
•  Selection of barnyard grass plants that
mimic cultivated rice (SE Asia)
•  Selection of herbicide resistant weed
species in crops (worldwide)
Weed removal
in rice
Latin America
•  weed removal involves the
ability to distinguish crops
and weed
•  weeds that look more like
the crop escape detection
inadvertently selecting for
mimicry
Africa
Rice mimicry in barnyard grass
Mimic
Rice
Barnyard
Grass
Scientific American (1987)
Rapid evolution of herbicide
resistant weeds in agriculture
crop duster
No of
resistant
weeds
widespread adoption
of herbicide spraying
Evolution by pollution
•  Evolution of heavy-metal tolerance in
grass species colonizing mine tailings
Independent evolution of heavy metal
tolerance in tufted hair grass at Sudbury
and Cobalt in the past 40 years
Canadian Journal of Botany (1993)
Climate change - how will
organisms respond?
•  Migrate to more favourable conditions
•  Go locally (or globally) extinct
•  Adapt to changing environmental
conditions*
- Annual mustard in California
- Perennial purple loosestrife in Ontario
* Will depend on the life history of species and
how much genetic variation occurs in populations
Can annual droughts cause
rapid contemporary evolution
by natural selection?
YES in 7 years flowering
evolved 8 days earlier
WET$YEAR$
Art Weis EEB
DRY$YEAR$
UCI$Arboretum$
Annual mustard in southern California
PNAS (2007)
Is the purple loosestrife
invasion associated with
adaptation to northern
climates in Ontario?
Yes – rapid evolution of local
adaptation to shorter growing
seasons in northern
populations in < 50 years
Proc Roy Soc Lond B (2010)
Evolution (2011)
Science (2013)
“Today, the theory of evolution is an accepted
fact for everyone but a fundamentalist
minority, whose objections are based not on
reasoning but on doctrinaire adherence to
religious principles”
James D. Watson (1965)
Molecular Biologist & Nobel Laureate
Nowhere is this tension between religious
beliefs and evolutionary evidence more
stark than over human evolution
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The correlation between belief in God and
acceptance of human evolution
among 34 countries
r = -0.61, P=0.0001
Coyne JA (2012) Evolution 66: 2654-2662
r = -0.71, P=0.0014
Relations between social
functionality and (A) belief
in God, (B) acceptance of
human evolution in 17
First World countries
•  Successful societal scale (SSS) = 1
least successful, 10 most successful
r = 0.69, P=0.0022
•  SSS incorporates 25 indices of
social well being including rates of
homicide, incarceration, juvenile
mortality, corruption, poverty, income
disparity, venereal disease etc.
Coyne JA (2012) Evolution 66: 2654-2662
This monkey mythology of
Darwin is the cause of
permissiveness, promiscuity,
pills, prophylactics,
perversions, abortions,
pornography, pollution,
poisoning, and proliferation of
crimes of all types
Judge Braswell Dean, Atlanta
Creationist Doctrine
•  Literal reading of Book Genesis
•  Creation of all living organisms by divine order in
6 days
•  All types of organisms individually created and
designed by a purposeful creator
Anyone who believes in Genesis as a literal
description of history holds a world view that is
entirely incompatible with evolution, and of
science itself
Scientific creationism is
not science because:
•  It is not supported by any empirical
observations
•  It does not infer its principles from
observation, as does all science
•  Its assumptions lead to no testable or
falsifiable hypotheses
If taught at high schools or universities it should not be in science classes !
Some last words
Science emphasizes evidence and logical
deduction. It deals not with facts engraved on
stone tablets, but with hypotheses that may be
refuted by tomorrow s experiments and concepts
formulated by fallible human minds. The best
scientific education encourages skepticism,
questioning, independent thought, and the use of
reason
Douglas J. Futuyma (1995)
Science on Trial
•  Science & religion are
incompatible because
religious methods are
useless for understanding
reality
Jerry Coyne Univ of Chicago
•  Science and religion
represent “non-overlapping
magisteria” – science is
concerned with facts about
the universe – religion the
orthogonal realm of
meaning, morals & values
•  “Accomodationist
strategies” will fail because
of the disparity between
obtaining truth by reason
and evidence versus faith
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Last thoughts
•  The future requires
fresh ideas and changing
paradigms
•  Incorporating ‘evolutionary
thinking’ into many disciplines
(e.g. conservation, health
sciences, agriculture) can
provide novel insights
•  But public understanding of
evolution is limited and some
deny evolution is true, so much
work ahead
Career change ?