Discrete and continuous character-based disparity analyses converge to the same macroevolutionary signal: a case...

Area of Science:

• Paleontology
• Evolutionary Biology
• Vertebrate Zoology

Background:

• Understanding the interplay between diversity and disparity is crucial for insights into evolutionary radiations, bottlenecks, and extinctions.
• Captorhinids, as basal amniotes, are key to deciphering the early evolution of herbivory, particularly high-fiber diets.

Purpose of the Study:

• To conduct the first comprehensive comparison of diversity and disparity in captorhinids.
• To analyze the evolutionary history of captorhinids using a new, fully resolved phylogeny and morphometric data.
• To investigate the relationship between diversity and disparity and its implications for adaptive radiations.

Main Methods:

• Construction of a new, fully resolved phylogeny for captorhinids incorporating 31 morphometric characters.
• Calculation of diversity and disparity metrics throughout the clade's evolutionary history.
• Utilized both discrete and continuous (morphometric) characters to assess disparity trends.

Main Results:

• Captorhinids exhibit a coupled relationship between diversity and disparity, without decoupling.
• A symmetric disparity distribution was observed, with a peak during the Kungurian stage, indicating a delayed adaptive radiation.
• The first appearance of high-fiber herbivores and numerous omnivorous taxa coincided with this radiation peak.
• Both discrete and continuous characters yielded consistent disparity trends.

Conclusions:

• The evolutionary history of captorhinids demonstrates a linked pattern of diversity and disparity.
• The observed peak in morphospace occupancy signifies a significant adaptive radiation event within the clade.
• Disparity trends derived from either discrete or continuous characters are robust and representative of the overall pattern, suggesting methodological flexibility.