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Some problems with assessing Cope's Rule.

Andrew R Solow1, Steve C Wang

  • 1Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. asolow@whoi.edu

Evolution; International Journal of Organic Evolution
|May 3, 2008
PubMed
Summary
This summary is machine-generated.

Cope's Rule suggests species size increases over evolutionary time. However, statistical testing reveals this rule is sensitive to how size is measured and lineage separation, complicating empirical assessment.

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Area of Science:

  • Evolutionary biology
  • Paleontology
  • Biostatistics

Background:

  • Cope's Rule posits a general trend of increasing body size in evolutionary lineages.
  • Empirical validation of Cope's Rule is crucial for understanding macroevolutionary patterns.

Purpose of the Study:

  • To develop a statistical framework for testing Cope's Rule.
  • To identify and address complications in the empirical assessment of Cope's Rule.

Main Methods:

  • Elucidation of a basic statistical framework for hypothesis testing.
  • Analysis of the invariance properties of Cope's Rule under different size metrics (mean vs. median).
  • Examination of sensitivity to ancestral-descendant species separation.

Main Results:

  • Formulating Cope's Rule based on mean size lacks invariance to the method of size measurement.
  • Formulating Cope's Rule based on median size lacks invariance to the degree of lineage separation.
  • Practical challenges in assessing Cope's Rule were identified.

Conclusions:

  • The statistical assessment of Cope's Rule is more complex than previously assumed.
  • Inconsistencies arise depending on the statistical formulation and data characteristics.
  • Implications for future empirical studies aiming to test Cope's Rule are significant.