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Molecular evolutionary rates predict both extinction and speciation in temperate angiosperm lineages
1National Center for Ecological Analysis and Synthesis, 735 State St,, Suite 300, Santa Barbara, CA 93101, USA. lancaster@nceas.ucsb.edu
BMC Evolutionary Biology
|June 3, 2010
Summary
Fast molecular evolution increases speciation and extinction rates in angiosperms. Higher substitution rates may aid diversification in changing environments, while lower rates reduce extinction during stable periods.
Area of Science:
- Evolutionary Biology
- Molecular Evolution
- Phylogenetics
Background:
- A positive correlation between speciation and nucleotide substitution rates is frequently observed in angiosperm clades.
- The causal factors driving this relationship remain unclear due to confounding intrinsic and extrinsic variables.
Purpose of the Study:
- To investigate the intrinsic causes of the diversification-substitution rate correlation in angiosperms.
- To differentiate between molecular evolution driving diversification versus diversification driving molecular evolution.
Main Methods:
- Utilized a novel database of 13 time-calibrated angiosperm phylogenies.
- Employed internal transcribed spacer (ITS) sequences for rate analysis.
- Controlled for extrinsic factors like life history and habitat variables.
Main Results:
- Speciation (lambda) and relative extinction (epsilon) rates positively correlated with mean substitution rates.
- No correlation found between diversification rates and substitution rate heterogeneity.
- Evidence does not support accelerated molecular evolution during speciation; rather, fast evolution appears to drive speciation and extinction.
Conclusions:
- Fast molecular evolution may increase speciation by providing mutational variation but also elevates extinction risk through genetic load.
- Higher background substitution rates may facilitate diversification under environmental change.
- Lower substitution rates might confer resilience against extinction during environmental stasis.
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