PASOS: a method for the phylogenetic analysis of shape ontogenies

Area of Science:

• Evolutionary Biology
• Phylogenetics
• Developmental Biology

Background:

• Phylogenetic analysis traditionally focuses on static traits, often overlooking developmental processes.
• Understanding evolutionary changes in developmental timing (heterochrony) is crucial for explaining morphological diversity.

Purpose of the Study:

• To develop a novel phylogenetic method for inferring ancestral ontogenies of shape characters.
• To quantify changes in developmental timing and shape evolution within a phylogenetic framework.

Main Methods:

• A parsimony-based approach using landmark data to minimize positional differences.
• Discretization of ontogenetic trajectories into stages to identify shifts in onset/offset of development.
• Implementation in a C language program named SPASOS.

Main Results:

• The method successfully infers ancestral shapes and evolutionary changes in developmental timing.
• Analysis of anurans and felids aligns with previous non-phylogenetic findings on shape evolution.
• Identified heterochronic events as key drivers of evolutionary change.

Conclusions:

• This novel phylogenetic approach provides a robust framework for studying the evolution of development.
• The SPASOS program facilitates the analysis of shape ontogeny and heterochrony in a phylogenetic context.
• Results support the integration of developmental timing into evolutionary morphology studies.