Nothing in Biology makes sense except in the
“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 et al.
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 (those living shared the Nobel Prize in 1962) DNA (genes) transcription Image of DNA double helix from Wikimedia Commons RNA translation Protein
Evolution – allele frequency change through time in a population Some Mechanisms of Evolution: Mutation Genetic drift (essentially random demographic processes) Gene flow via emigration, immigration, and dispersal of gametes Artificial selection Natural selection (Darwin, and Wallace) – adaptive evolution Sexual selection: competition for mates, generally via (1) male-male competition or (2) female choice (Darwin) – adaptive evolution Phenotypic change followed by genetic accommodation (Baldwin, and more recently 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 Selection Directional Peter & Rosemary Grants’ (2003) study of G. fortis Bowman, Hacker & Cain (2017), Fig. 6. 6 A
Types of Selection Stabilizing Weis’s & Abrahamson’s (1986) study of Eurosta flies that parasitize goldenrods Bowman, Hacker & Cain (2017), Fig. 6. 6 B
Types of Selection Disruptive Smith’s (1993) study of African seedcrackers Bowman, Hacker & Cain (2017), 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 Bowman, Hacker & Cain (2017), 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 Bowman, Hacker & Cain (2017), Fig. 6. 21
Evolution – “descent with modification” Darwin (1859) Darwin’s (1837) sketch of an evolutionary tree and a modern phylogeny of life from Wikimedia Commons
Evolution Douglas J. Emlen Photo of Emlen from http: //dbs. umt. edu/emlenlab/People. htm; book jacket from Amazon. com
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
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 Speciation Allele frequency change through time in a population Adaptive radiation Mass extinction E. g. , Population genetics E. g. , Comparative genomics Paleontology Phylogenetics Spatial & Temporal Scales (On average the scales over which micro-evolution occurs are smaller relative to those over which macro-evolution occurs, but not necessarily)
Image from Wikimedia Commons mya Cretaceous-Tertiary Triassic-Jurassic Permian-Triassic Late Devonian Ordovician-Silurian Percent of all marine genera Mass Extinction
Earth’s History on a Football Field (Metaphoric Time Scale) Note that the timeline in the previous figure is only the most recent 0. 542 billion years https: //www. youtube. com/watch? v=M 8 V_gl. RW 1 h. A
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
“Nothing in Biology makes sense except in the light of Evolution” Theodosius Dobzhansky (1973) Iconic Christmas Island red crab This female has symmetrical pleopods on her abdomen to hold her egg mass K. Harms photo
“Nothing in Biology makes sense except in the light of Evolution” Theodosius Dobzhansky (1973) Coconut or robber crab Christmas Island, Indian Ocean Hermit crabs with asymmetrical pleopods K. Harms photos; drawing of hermit crab from http: //crabstreetjournal. org/blog/tag/hermit-crab/page/14/
- Slides: 28