Patterning and post-patterning modes of evolutionary digit loss in mammals.

Area of Science:

• Developmental biology
• Evolutionary biology
• Comparative anatomy

Background:

• Digit reduction is a common evolutionary adaptation in cursorial mammals.
• The developmental mechanisms driving digit loss have been poorly understood.

Purpose of the Study:

• To investigate the developmental mechanisms underlying digit loss in various mammalian species.
• To understand the evolutionary plasticity in limb development.

Main Methods:

• Comparative analysis of limb development in jerboa, horse, camel, and pig.
• Examination of cell death and gene expression patterns during chondrogenesis.

Main Results:

• Digit loss can occur during early limb patterning or later chondrogenesis stages.
• Jerboa, horse, and camel exhibit significant cell death for digit sculpting.
• Pig digit loss involves early patterning changes, including Ptch1 downregulation, without increased cell death.

Conclusions:

• Vertebrate limb evolution shows remarkable plasticity in developmental mechanisms.
• Morphological convergence, especially in artiodactyls, involves diverse evolutionary strategies.