Ascidians and the plasticity of the chordate developmental program

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Comparative Genomics

Background:

• Invertebrate chordates like tunicates (ascidians) and cephalochordates are descendants of ancient chordates.
• Tunicate larvae share a basic body plan with vertebrate embryos, including a notochord and dorsal nerve cord.
• Tunicates are considered the sister group to vertebrates, but their developmental strategies differ significantly.

Purpose of the Study:

• To compare developmental strategies between ascidians and vertebrates.
• To highlight the plasticity of the chordate developmental program.
• To identify evolutionarily conserved regulatory mechanisms and understand the origin of the chordate body plan.

Main Methods:

• Comparative analysis of developmental strategies.
• Examination of gene regulatory networks in ascidians and vertebrates.

Main Results:

• Ascidian and vertebrate molecular developmental strategies diverge considerably.
• The adult body plan of most tunicates, post-metamorphosis, differs from other chordates.
• Developmental divergence underscores the plasticity of the chordate developmental program.

Conclusions:

• Comparative analysis of ascidian and vertebrate development reveals significant plasticity in chordate evolution.
• Studying these differences can identify core regulatory mechanisms conserved across chordates.
• Analyzing gene regulatory networks offers insights into the evolution of the chordate body plan.