Jeong DageumUST

2009/11/04

Gene duplicationPolyploidization

Genomic ExpansionRapid

cladogenetic

Speciation

<Fish taxa><Observation and Theory>

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southdakotapolitics.blogs.com/

Genome sizePatterns of

evolutionary radiation

Poorly characterized

?

<General relationship>

<Question>

Genome size(C-value)

Species richness

Empirical correlations

<Solution and Results>

461 genera

Positive correlations

Genomic architecture may play a role

in species proliferations

Introduction Material and methods Results Discussion

(a) Qualifications(b) Genome dynamics and cladogenesis

Introduction[Observation]Large-scale genomic expansionWhole-genome duplication events

In early vertebrate evolutionEx) Teleost fishes, salmonids, catastomids, acipenserids, cyprinids….

Little comparative work has tested for the hypothesized correlations

Genomic enlargements -> key factor of enable to drive diversification

[Hypothesis]

[Test study]

Introduction[hypothesis]

Genomic architecture

Speciation rates

Several mechanism ( Duplicated loci)1. - Evolve new functions

- Evolve new structural, catalytic, or regulator roles2. Become mutationally silenced3. Reciprocal silencing of complimentary duplicate genes

* Repetitive transposable elements-> Alter Gene expression patterns-> Alter genomic profiles

Genomic Divergence & expansions

IntroductionAmong vertebrates

Mammals, birds, reptilesGenome size- Relatively small variation

Ray-finned fishesGenome size-Relatively high variation

Puffer fish- 0.39 pg of DNA per cell(Fugu rubripes) ~Armoured catfish - 4.4 pg DNA per cell(Corydoras aeneus)

Examine empirical relationships between genome dynamics and radiations

Material and methods1. Haploid genome sizes (pg DNA )2. C-values within each genus3. Extant species for each genus 4. Least squares regression

Correlation coefficents (r) Significance (p)

All 461 geera as independent observationsw/o regard to their phylogenetic assocations

To correct for phylogeny, - use supertree(independent contrasts)for Actinopterygii-Measure species richness (macroCAIC)http://www.bio.ic.ac.uk/evolve/software/macrocaic/

Results

0.39pg/cell(pufferfish genus Chelonodon)

to 3.57 pg/cell(sturgeon genus Acipenser)

Showing a roughly normal distribution around a mean of 1.19 pg/cell

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mypetjawa.mu.nu/archives

Results

Phylogenetically Uncorrected

Phylogenetically corrected

C-value: picograms DNA per haploid cell

PositiveCorrelation

PositiveCorrelation

Discussion

Super order

Super order

Discussion

Discussion

Correction by independent contrast

Discussion

Discussion

Ray finned fishes

- Evolutionarily labile in DNA content

- Apparently expanding and contracting rather quickly

Via

Extensive duplications and losses of genetic material.

Discussion

Often-hypothesized link <<<<<<<

Genome dynamics Speciations

<Confounding variables>Qualifications - noise

Discussion(a) Qualifications

Noise1. Differential extinction rate

focusing on genera

2. Taxonomic biases (ex: genomic enlargements-> split into more genera)

3. Exception of information on branch lengths or evolutionary time scale

Discussion(b) Genome dynamics and cladogenesis

Changes in genome size - > increased probabilities of cladogensis- alteration of gene expression patterns- reciprocal silencing of redundant duplications

Speciation: A multifaceted phenomenon

Genomic dynamism: includes many ecological and behavioural considerations

-> but this significant association -> quite surprising.