Stem Arthropods

Stem Arthropods

Anomalocaris Opabinia Hurdia

Erwin and Valentine, The Construction of Animal Biodiversity, 2013

Erwin and Valentine, The Construction of Animal Biodiversity, 2013

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)

Erwin et al. 2011, Science

Strongylocentrotus

Sea Urchin dGRN

Biotapestry.org

Sea Urchin endomesoderm GRN

Gene Regulatory Network Structure

Erwin and Valentine, Forthcoming, 2012; after Davidson

Davidson & Erwin, 2009

Origin of Eumetazoa

Origin of DevelopmentalToolkit

Increase in miRNA families; complexity

of dGRN interactions

Most signalling pathwayspresent

Fedonkin et al The Rise of Animals, 2007

Erwin and Valentine, Forthcoming, 2012

Gen

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Natural selectionGene pool

Gene pool

Eco

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Natural selection

Gen

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Gene pool

Gene pool

Natural selection

Natural selection

EcologicalSpillover

EcologicalSpillover

Species 1Species 2

Ecosystem Engineering

Cambrian Ecosystem Engineering

• Archaeocyathid reefs (+)• Sponges & other filter

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

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

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”

• 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

Origin of Eumetazoa

Origin of DevelopmentalToolkit

Increase in miRNA families; complexity

of dGRN interactions

Most signalling pathwayspresent

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)

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

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

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

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 (?)

Nature of Contingency

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

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?

Modern Synthesis

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

of evolution• Opportunistic• Uniformitarian

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

Search Vs Construction

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

Grassland Evolution

Grass Phylogeny

Kellogg, 2001, Plant Physiology

Macroevolutionary Lags

How are new evolutionary spaces created?

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

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