stem arthropods
DESCRIPTION
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 PresentationTRANSCRIPT
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
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
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