Tree of life reveals clock-like speciation and diversification

Area of Science:

• Evolutionary Biology
• Genomics
• Phylogenetics

Background:

• Genomic data are crucial for constructing the timetree of life, a framework for scientific research.
• Previous studies on limited timetrees suggested declining diversification rates, often linked to ecological interactions.
• Potential biases like limited taxon sampling and clade size may have affected prior analyses.

Purpose of the Study:

• To synthesize a comprehensive global timetree of life.
• To examine patterns and rates of species diversification and speciation timing.
• To identify and mitigate biases in diversification analyses.

Main Methods:

• Synthesized data from 2,274 studies, encompassing 50,632 species.
• Constructed a global timetree of life.
• Analyzed diversification patterns, rates, and speciation timing, while accounting for potential biases.

Main Results:

• Species diversity has been expanding overall and within many smaller groups.
• The rate of diversification in eukaryotes has remained largely constant.
• Speciation intervals (time-to-speciation) for plants and animals are consistently around 2 million years.

Conclusions:

• Diversification and speciation appear to be driven primarily by random events.
• Adaptive change is likely a separate process from diversification.
• The findings provide a robust framework for understanding life's evolutionary history.