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The soft explosive model of placental mammal evolution
Matthew J Phillips1, Carmelo Fruciano2
1School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Australia. m9.phillips@qut.edu.au.
BMC Evolutionary Biology
|July 5, 2018
Summary
Molecular clock estimates for placental mammal evolution are often too early. New simulations show that accounting for rate changes and using specific calibrations improve accuracy, supporting a rapid diversification after the Cretaceous-Paleogene extinction.
Area of Science:
- Evolutionary Biology
- Paleontology
- Molecular Evolution
Background:
- Molecular dating of placental mammal diversification often conflicts with fossil records, placing the event earlier than expected.
- Existing molecular clock models fail to account for rate changes, leading to underestimates in large, long-lived mammals.
Purpose of the Study:
- To reconcile discrepancies between molecular dating and fossil evidence for placental mammal evolution.
- To develop improved molecular dating methods by addressing rate variation and calibration strategies.
Main Methods:
- Utilized simulations based on empirical rate variation to model molecular evolution.
- Focused on calibrations using taxa with plesiomorphic life-history characteristics to enhance dating accuracy.
- Applied improved methods to empirical data to test evolutionary models.
Main Results:
- Simulations demonstrated that "error-shift inflation" in molecular dating can overestimate divergence times.
- Using appropriate calibrations significantly improved molecular dating accuracy.
- Empirical data analysis favored the "soft explosive" model of placental mammal evolution.
Conclusions:
- The "soft explosive" model, proposing rapid diversification after the Cretaceous-Paleogene extinction, aligns molecular, fossil, and life history data.
- Criticisms of the "soft explosive" model often overlook experimental controls and statistical rigor.
- Adaptive radiations may inherently challenge current molecular dating methods, potentially leading to overestimations of diversification timings.
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