The effect of branch diameter on primate gait sequence pattern.

Area of Science:

• Primate locomotion
• Comparative biomechanics
• Evolutionary biology

Background:

• Most mammals exhibit lateral sequence gaits.
• Primates commonly use diagonal sequence (DS) gaits, potentially linked to arboreal habitats.
• The adaptive significance of DS gaits on varied substrates remains debated.

Purpose of the Study:

• To investigate the relationship between branch diameter and gait patterns in strepsirrhine primates.
• To test the hypothesis that DS gaits provide an advantage on narrow arboreal supports.

Main Methods:

• Collected 360 strides from six species of quadrupedal strepsirrhine primates.
• Compared gait patterns on broad and narrow diameter supports.
• Quantified gait sequence using limb phase analysis.

Main Results:

• Locomotor velocity was significantly reduced on narrower supports for some species.
• No significant differences in limb phase (gait sequence) were observed between broad and narrow supports.
• Gait alterations do not appear to be a primary adaptation for negotiating narrow branches.

Conclusions:

• The study provides limited evidence supporting the advantage of DS gaits on narrow supports.
• Alternative explanations for primate DS gait preference may be necessary.
• Locomotor adjustments beyond gait sequencing are likely crucial for navigating complex arboreal environments.