The Clade Replacement Theory: a framework to study age-dependent extinction

Area of Science:

• Evolutionary biology
• Ecology
• Paleontology

Background:

• The relationship between species' evolutionary age and extinction probability lacks scientific consensus.
• Existing studies propose various age-dependent extinction (ADE) patterns, but a universal pattern remains debated.
• Closely related species may exhibit similar ADE patterns due to shared fitness-associated traits.

Purpose of the Study:

• To formalize the Clade Replacement Theory (CRT) integrating ecological and evolutionary aspects of species age and extinction.
• To develop testable predictions for ADE patterns based on clade competition and environmental dynamics.
• To provide a framework for unifying research on age-dependent extinction.

Main Methods:

• Developing the Clade Replacement Theory (CRT) based on previous theoretical work.
• Formalizing propositions regarding incumbency effects and ecological shifts influencing ADE.
• Deriving predictions on ADE scenarios based on the occurrence of ecological shifts.

Main Results:

• The CRT predicts two main ADE scenarios: negative (younger species more prone to extinction) due to incumbency, and positive (extinction probability increases with age) due to ecological shifts.
• The occurrence of an ecological shift is predicted to define the prevailing ADE scenario.
• The theory offers a unified framework to analyze diversification dynamics and extinction selectivity.

Conclusions:

• The Clade Replacement Theory (CRT) provides a robust framework for understanding age-dependent extinction (ADE).
• Future empirical testing of CRT predictions is crucial for validating its applicability across diverse taxa.
• CRT can unify disparate findings in evolutionary biology and ecology, fostering new research avenues.