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Macroevolutionary diversification rates show time dependency.

L Francisco Henao Diaz1,2, Luke J Harmon3, Mauro T C Sugawara1,2

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Biodiversity varies across species due to differing speciation and extinction rates. This study reveals these macroevolutionary rates are linked to clade age, with younger groups exhibiting faster rates, suggesting simple principles drive biodiversity dynamics.

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Area of Science:

  • Evolutionary Biology
  • Ecology
  • Paleontology

Background:

  • Biologists have long observed significant variations in species richness among different taxa.
  • Differences in speciation and extinction rates are commonly cited as primary drivers of this diversity.
  • Previous macroevolutionary studies have estimated these rates for numerous groups and linked them to various traits.

Purpose of the Study:

  • To investigate a potential underlying generality in macroevolutionary rates across diverse clades.
  • To determine if speciation and extinction rates exhibit a predictable pattern related to group age.
  • To test the robustness of observed patterns against statistical artifacts.

Main Methods:

  • Analysis of a comprehensive dataset of phylogenetic trees.
  • Examination of fossil time series data.
  • Conducting simulations and sensitivity analyses to validate findings.

Main Results:

  • A universal scaling law was identified where both speciation and extinction rates are dependent on the age of the clade.
  • The youngest clades (youngest groups of organisms) exhibit the highest rates of speciation and extinction.
  • Statistical analyses indicate that this time dependency is not an artifact but a genuine biological pattern.

Conclusions:

  • Macroevolutionary rates are not static but follow a predictable time-dependent scaling law.
  • This finding suggests that the age of a clade is a critical factor influencing its diversification dynamics.
  • Simple, general principles may govern the complex dynamics of biodiversity across evolutionary time.