Morphological Variation in Anuran Limbs: Constraints and Novelties

Area of Science:

• Zoology
• Evolutionary Biology
• Morphology

Background:

• Anurans exhibit diverse locomotion, including walking, jumping, and swimming, facilitated by their four limbs.
• Limb morphology and skeletal organization are key to understanding anuran diversification and adaptation.
• Previous research has explored anuran limb variation, but a comprehensive update and discussion of developmental influences are needed.

Purpose of the Study:

• To summarize and update knowledge on interspecific variation in anuran limbs.
• To discuss how developmental constraints and novelties influenced anuran diversification through locomotion.
• To analyze morphological variation from limb bud to adult stages.

Main Methods:

• Analysis of morphological variation in anuran limbs across developmental stages.
• Examination of skeletal organization and growth patterns.
• Identification of specialized skeletal features related to locomotion.

Main Results:

• Anuran body shape is largely constrained, with limited morphometric variation across skeletal modules.
• Specializations in the stylopodium, zeugopodium, and proximal carpals/tarsals facilitate saltatorial (jumping) locomotion.
• The prepollex and prehallux are functional digits, not vestigial, and intercalary elements aid arboreal locomotion in neobatrachians.

Conclusions:

• Anuran limb evolution demonstrates a balance between developmental constraints and the emergence of novelties.
• Skeletal specializations in anuran limbs are crucial for diverse locomotor behaviors and habitat exploitation.
• Understanding limb morphology provides insights into the evolutionary pathways and diversification of anurans.