Transcript Slide 1
“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