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Stem Arthropods

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Stem Arthropods. Anomalocaris. Opabinia. Hurdia. Erwin and Valentine, The Construction of Animal Biodiversity, 2013. Erwin and Valentine, The Construction of Animal Biodiversity, 2013. Genomic Complexity. (Erwin, 2009; Erwin & Valentine 2013). Erwin et al. 2011, Science. - PowerPoint PPT Presentation

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Stem Arthropods

Anomalocaris Opabinia Hurdia

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Erwin and Valentine, The Construction of Animal Biodiversity, 2013

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Erwin and Valentine, The Construction of Animal Biodiversity, 2013

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Monosiga Amphimedon Trichoplax Nematostella Drosophila

genome size (Mb) 41.6 167 98 450 180

# genes 9,100 ? 11,514 18,000 14,601

# cell types 1 12 4 20 50

# T.F.’s ? 57 35 min. 87 min. 87

# T.F. families 5 6? 9 10 10

microRNA 0 8 0 40 152

Genomic Complexity

(Erwin, 2009; Erwin & Valentine 2013)

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Erwin et al. 2011, Science

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Strongylocentrotus

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Sea Urchin dGRN

Biotapestry.org

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Sea Urchin endomesoderm GRN

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Gene Regulatory Network Structure

Erwin and Valentine, Forthcoming, 2012; after Davidson

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Davidson & Erwin, 2009

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Origin of Eumetazoa

Origin of DevelopmentalToolkit

Increase in miRNA families; complexity

of dGRN interactions

Most signalling pathwayspresent

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Fedonkin et al The Rise of Animals, 2007

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Erwin and Valentine, Forthcoming, 2012

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Gen

etic

inhe

ritan

ce

Et

Et+1

Natural selectionGene pool

Gene pool

Eco

logi

cal i

nher

itanc

e

Natural selection

Gen

etic

inhe

ritan

ce

Gene pool

Gene pool

Natural selection

Natural selection

EcologicalSpillover

EcologicalSpillover

Species 1Species 2

Ecosystem Engineering

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Cambrian Ecosystem Engineering

• Archaeocyathid reefs (+)• Sponges & other filter

feeders (+)• Burrowed sediments (+/-)• Shelly substrates (+)• Mesoozooplankton (+)

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Ecological Spillovers

• Sponges: sequestering carbon via filtration. Oxidation of oceans allow increased production of collagen.

• Burrowing: change in S isotopes, enhances primary productivity in seds, increases biodiversity

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P & P Definitions

• Innovation “improve on existing ways of doing things” (which sounds to a biologist like adaptation)

• Inventions “change the ways things are done”

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• Invention is the creation of something new and distinct (contrast with variation on established themes)

• Innovation occurs when inventions become economically or ecologically significant

Invention & Innovation

JosephSchumpeter(1883-1950

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Origin of Eumetazoa

Origin of DevelopmentalToolkit

Increase in miRNA families; complexity

of dGRN interactions

Most signalling pathwayspresent

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Defining Novelty

• Are ‘novelty’ and ‘innovation’ synonymous? • Character based: new construction elements of

a body plan (not homologous to pre-existing structure)

• Process based: novelty should involve a transition between adaptive peaks and a breakdown of ancestral developmental constraints so that new sorts of variation are generated (Halgrimsson et a. 2012 J. Exp. Zool)

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• Evolutionary novelty originates when part of the body acquires individuality and quasi-independence

• Involves origin of new character identity rather than character state (homology)

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How are new evolutionary spaces created?

• Potentiated by broader environmental setting (physical, genetic, ecologic)

• Actualized by genetic and developmental innovations leading to a new clade

• Refined by further developmental and ecological changes

• Realized as innovations by ecological expansion and evolutionary success

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Mechanisms of Organizational Genesis

• Transposition and refunctionality (var)• Anchoring diversity (ecology)• Incorporation and detachment (var)• Migration and homology (niche const)• Conflict displacement/dual inclusion (ETI)• Purge and mass mobilization (ecology)• Privatization and Business groups (ecol/ETI)• Robust action and multivocality (?)

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Nature of Contingency

• Sampling error• Unpredictability of the course of history• Sensitivity to initial conditions (Beatty 2006)• Sensitivity to external disturbance• Macroevolutionary stochasticity

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Nature of Contingency

• Sampling error• Unpredictability of the course of history• Sensitivity to initial conditions (Beatty 2006)• Sensitivity to external disturbance• Macroevolutionary stochasticity

And does the ‘topography’ of historical contingency change over time?

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Modern Synthesis

• Transmission Genetics • Simple path from genotype to phenotype• Primacy of genetic inheritance• Selection within populations as primary driver

of evolution• Opportunistic• Uniformitarian

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Emerging Perspectives

• No simple mapping from genotype to phenotype (evo-devo)

• Multiple forms of inheritance• Multiple levels of selection• Important roles for mutation and drift in

addition to selection• Macroevolutionary lags• Non-uniformitarian

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Search Vs Construction

• Innovation is often described as search through a space of “the adjacent possible” (Kaufmann, Wagner)

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Grassland Evolution

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Grass Phylogeny

Kellogg, 2001, Plant Physiology

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Macroevolutionary Lags

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How are new evolutionary spaces created?

• Potentiated by broader environmental setting (physical, genetic, ecologic)

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How are new evolutionary spaces created?

• Potentiated by broader environmental setting (physical, genetic, ecologic)

• Actualized by genetic and developmental innovations leading to a new clade