Developmental mechanisms underlying webbed foot morphological diversity in waterbirds

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Comparative Anatomy

Background:

• Waterbird feet exhibit diverse morphologies, including palmate, semipalmate, totipalmate, and lobate types.
• Understanding the developmental basis of this diversity is crucial for evolutionary studies.

Purpose of the Study:

• To investigate the developmental mechanisms underlying the morphological diversity of waterbird webbed feet.
• To explore the role of Gremlin1 in the development of different foot types.

Main Methods:

• Comparative analysis of webbed foot morphology in various waterbird species.
• Ancestral state reconstruction based on phylogenetic data.
• Examination of Gremlin1 gene expression patterns and cell proliferation in embryonic waterbird feet.

Main Results:

• Lobate feet in the common coot and little grebe likely evolved independently through distinct developmental processes.
• Differences in Gremlin1 expression and cell proliferation support convergent evolution of lobate feet.
• The totipalmate foot of the great cormorant shows unique Gremlin1 expression dynamics, suggesting distinct developmental origins compared to palmate feet.

Conclusions:

• The evolution of waterbird foot morphology is shaped by diverse developmental mechanisms.
• Gremlin1 plays a significant role in regulating interdigital cell death and shaping webbed feet.
• Convergent and distinct evolutionary pathways contribute to the variety of waterbird foot types.