K-Pg events facilitated lineage transitions between terrestrial and aquatic ecosystems

Area of Science:

• Evolutionary biology
• Paleontology
• Vertebrate zoology

Background:

• Tetrapod vertebrates inhabit diverse terrestrial and aquatic environments.
• Evolutionary transitions between ecosystems can be driven by environmental changes and competitive pressures.
• Mass extinction events significantly alter ecological landscapes and evolutionary trajectories.

Purpose of the Study:

• To identify tetrapod lineages that transitioned between terrestrial and aquatic ecosystems.
• To determine the timing of these ecological shifts in feeding or development.
• To evaluate the correlation between mass extinctions and the frequency of such transitions.

Main Methods:

• Construction and analysis of dated phylogenetic trees for tetrapod vertebrates.
• Mapping ecological shifts (feeding, development) onto phylogenetic lineages.
• Temporal analysis of transition events in relation to geological timescales, specifically the K-Pg mass extinction.

Main Results:

• Phylogenetic analyses revealed numerous lineage shifts between terrestrial and aquatic habitats.
• Both stem and crown lineage ages indicated a peak in transition events coinciding with the K-Pg mass extinction.
• The timing of these transitions supports hypotheses linking mass extinctions to increased evolutionary opportunities.

Conclusions:

• Mass extinction events, like the K-Pg, act as significant drivers for ecological and developmental transitions in vertebrates.
• Changes in competition and resource availability post-extinction facilitate niche-filling and evolutionary innovation.
• Phylogenetic analyses provide a robust framework for understanding macroevolutionary patterns and environmental influences.