PHYLOGENIES WITHOUT FOSSILS.

Area of Science:

• Evolutionary Biology
• Phylogenetics
• Computational Biology

Background:

• Phylogenetic trees reconstructed without fossil data often yield approximate divergence times.
• Molecular phylogenies are frequently calibrated using geographic events to estimate divergence times.
• These phylogenies do not directly represent extinct lineages but offer insights into evolutionary processes.

Purpose of the Study:

• To determine the expected appearance of phylogenies under a constant birth-death process.
• To investigate the possibility of estimating lineage birth and death rates from such phylogenies.
• To explore how phylogenies can identify mass extinction events and distinguish them from density-dependent cladogenesis.

Main Methods:

• Modeling phylogenetic tree reconstruction under a birth-death process with constant rates.
• Developing methods to estimate lineage birth and death rates from tree topology and node ages.
• Analyzing the characteristic patterns of phylogenies resulting from mass extinctions.

Main Results:

• Birth and death rates of lineages can be estimated from phylogenies even without explicit data on extinct lineages.
• Phylogenies reconstructed under a birth-death process exhibit predictable characteristics.
• Mass extinctions leave a discernible signature in phylogenies that can be distinguished from other evolutionary dynamics.

Conclusions:

• Phylogenetic trees, even those without fossil data, contain valuable information about evolutionary rates and past extinction events.
• The birth-death model provides a framework for interpreting molecular phylogenies and inferring macroevolutionary dynamics.
• This approach enhances our understanding of evolutionary history and the impact of major extinction events.