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Stem Arthropods

This article explores the mechanisms and processes by which evolutionary novelty and innovation arise in animal biodiversity, focusing on the Cambrian explosion and the construction of new body plans. It discusses the role of genetic and developmental innovations, ecological constraints, environmental factors, and the interplay between invention and adaptation.

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Stem Arthropods

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  1. Stem Arthropods Anomalocaris Opabinia Hurdia

  2. Erwin and Valentine, The Construction of Animal Biodiversity, 2013

  3. Erwin and Valentine, The Construction of Animal Biodiversity, 2013

  4. Genomic Complexity (Erwin, 2009; Erwin & Valentine 2013)

  5. Erwin et al. 2011, Science

  6. Strongylocentrotus

  7. Sea Urchin dGRN Biotapestry.org

  8. Sea Urchin endomesoderm GRN

  9. Gene Regulatory Network Structure Erwin and Valentine, Forthcoming, 2012; after Davidson

  10. Davidson & Erwin, 2009

  11. Increase in miRNA families; complexity of dGRN interactions Origin of Developmental Toolkit Origin of Eumetazoa Most signalling pathways present

  12. Fedonkin et al The Rise of Animals, 2007

  13. Erwin and Valentine, Forthcoming, 2012

  14. Ecosystem Engineering Species 2 Species 1 Natural selection Natural selection Et Gene pool Gene pool Ecological Spillover Ecological inheritance Genetic inheritance Genetic inheritance Natural selection Natural selection Et+1 Gene pool Gene pool Ecological Spillover

  15. Cambrian Ecosystem Engineering • Archaeocyathid reefs (+) • Sponges & other filter feeders (+) • Burrowed sediments (+/-) • Shelly substrates (+) • Mesoozooplankton(+)

  16. 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

  17. 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”

  18. Invention & Innovation • Invention is the creation of something new and distinct (contrast with variation on established themes) • Innovation occurs when inventions become economically or ecologically significant Joseph Schumpeter (1883-1950

  19. Increase in miRNA families; complexity of dGRN interactions Origin of Developmental Toolkit Origin of Eumetazoa Most signalling pathways present

  20. 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)

  21. Evolutionary novelty originates when part of the body acquires individuality and quasi-independence • Involves origin of new character identity rather than character state (homology)

  22. 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

  23. 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 (?)

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

  25. 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?

  26. Modern Synthesis • Transmission Genetics • Simple path from genotype to phenotype • Primacy of genetic inheritance • Selection within populations as primary driver of evolution • Opportunistic • Uniformitarian

  27. 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

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

  29. Grassland Evolution

  30. Grass Phylogeny Kellogg, 2001, Plant Physiology

  31. Macroevolutionary Lags

  32. How are new evolutionary spaces created? • Potentiated by broader environmental setting (physical, genetic, ecologic)

  33. 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

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