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“Nothing in Biology makes sense except in the light of Evolution”
Theodosius Dobzhansky (1973)
“The evolutionary play takes place in an ecological theater”
G. Evelyn Hutchinson (1965)
Photos of a well-protected gastropod mollusk shell from Wikimedia Commons
Evolution
Charles Darwin
“On the Origin of Species
by Means of Natural
Selection”
(1859)
Photo of Darwin from Wikimedia Commons
Evolution
Alfred Russel Wallace
Darwin’s & Wallace’s ideas
were presented together to
the Linnean Society of
London in 1858
Photo of Wallace from Wikimedia Commons
Modern Evolutionary Synthesis
J. Huxley’s term (Evolution: The Modern Synthesis, 1942) for the synthetic
paradigm that emerged between 1936 and 1947 to bind together
evolution by natural selection, population genetics, development, etc.
Principal Architects:
S. Chetverikov
Th. Dobzhansky
R. A. Fisher
E. B. Ford
J. B. S. Haldane
E. Mayr
B. Rensch
G. G. Simpson
G. L. Stebbins
S. Wright
Central Dogma of Molecular Biology
J. Watson & F. Crick; R. Franklin & R. Gosling; M. Wilkins
1953 – structure of DNA
1956 – essay by Crick re Central Dogma
DNA
(genes)
transcription
Image of DNA double helix from Wikimedia Commons
RNA
translation
Protein
Evolution
Evolution – allele frequency change through
time in a population
Some Mechanisms of Evolution:
Mutation
Random processes (e.g., genetic drift)
Gene flow via emigration & immigration
Artificial selection
Natural selection (Darwin [& Wallace]) – adaptive evolution
Sexual selection: (1) male-male competition; (2) female choice
(Darwin) – adaptive evolution
Phenotypic change followed by genetic accommodation
(M. J. West-Eberhard) – adaptive evolution
Adaptive Evolution – traits that confer a fitness advantage are favored
Heritability
Adaptive evolution depends on heritable traits
Geospiza fortis
(a Darwin’s finch)
Boag (1983) Evolution, Fig. 1; photo of G. fortis from Wikimedia Commons
Types of Natural Selection
Directional
Peter & Rosemary Grants’
(2003) study of G. fortis
Cain, Bowman & Hacker (2014), Fig. 6.6 A
Types of Natural Selection
Stabilizing
Weis’s &
Abrahamson’s
(1986) study of
Eurosta flies that
parasitize goldenrods
Cain, Bowman & Hacker (2014), Fig. 6.6 B
Types of Natural Selection
Disruptive
Smith’s (1993) study
of African
seedcrackers
Cain, Bowman & Hacker (2014), Fig. 6.6 C
Tempo of Evolution
E.g., rapid adaptive evolution
Carroll’s & Boyd’s
(1992) study of
soapberry bugs;
evolution of beak
length in 35 yr
Native species
Exotic / introduced species
Cain, Bowman & Hacker (2014), Fig. 6.11
Speciation
Modes of Speciation
Image from Wikimedia Commons
Speciation
Additional Mode of Speciation: Hybridization
Rieseberg et al.
(2003) study of wild
sunflowers
Cain, Bowman & Hacker (2014), Fig. 6.21
Evolution
Evolution – “descent with modification”
Darwin (1859)
Darwin’s (1837) sketch of an evolutionary tree and a modern phylogeny of life from Wikimedia Commons
Evolution
Possibly apocryphal response to theologians who asked J. B. S. Haldane what
could be inferred about the mind of the Creator from the works of His Creation:
"An inordinate fondness for beetles"
Image from http://aninordinatefondness.wordpress.com/
Evolution
Douglas J. Emlen
Photo of Emlen from http://dbs.umt.edu/emlenlab/People.htm
Evolution
Development
(Genotype + Environment  Phenotype)
Phenotypic Plasticity
Diet influences body size
Body size influences horn size
Sigmoidal allometry
results in bimodal
horn size distribution
Emlen (1996) Evolution, Fig. 1
Evolution
Individuals are the units of selection, but populations evolve
Each symbol is an individual and
each curve in the inset could be
an individual’s potential
allometry
Evolution could shift the
population-level allometry
Emlen (1996) Evolution, Fig. 2
Evolution
Costs & Benefits / Trade-offs
There’s no free lunch!
The jack-of-all-trades is master of none!
Nijhout & Emlen (1998) Proceedings of the National Academy of Sciences, Fig. 1 d & e
Evolution
Geerat J. Vermeij
Photo of Vermeij from http://geology.ucdavis.edu/people/faculty/vermeij.php
Evolution
Evolutionary arms races between predators & prey:
co-evolution of defenses & counter-defenses
Photo of well-protected gastropod mollusks from Wikimedia Commons
Beware of Unfounded “Adaptive Story Telling”
Stephen J. Gould & Richard Lewontin brought critical attention to
“just so stories” in evolutionary biology
NO!
Photo of Gould from Wikimedia Commons
Micro- & Macro-Evolution
Microevol. Scale  within populations or species
Macroevol. Scale  across separated gene pools
Allele frequency change through
time in a population
E.g., Population genetics
Speciation
Adaptive radiation
Mass extinction
E.g., Comparative genomics
Paleontology
Phylogenetics
Spatial & Temporal Scales
Image from Wikimedia Commons
mya
Cretaceous-Tertiary
Triassic-Jurassic
Permian-Triassic
Late Devonian
Ordovician-Silurian
Percent of all marine genera
Mass Extinction
Evolution
Neil Shubin
Photo of Shubin & Tiktaalik (“missing link” between fishes & amphibians) from Wikimedia Commons
Evolution
Peter & Rosemary Grant
Photo of Grants from Princeton University