Ecogeographical and phylogenetic effects on craniofacial variation in macaques

Area of Science:

• Primatology
• Evolutionary Biology
• Morphometrics

Background:

• Macaque ecogeographical diversity complicates phylogenetic analysis due to potential adaptive morphological convergence.
• Understanding craniofacial variation is key to resolving macaque evolutionary relationships.

Purpose of the Study:

• To investigate the influence of ecogeographical and phylogenetic factors on macaque craniofacial morphology.
• To test the hypothesis that craniofacial morphology varies with environmental and evolutionary factors.

Main Methods:

• Geometric morphometrics and multivariate statistical analyses were employed.
• Craniofacial morphology data were analyzed in relation to ecogeographical and phylogenetic information.

Main Results:

• Body size in fascicularis and sinica groups increased in colder climates, aligning with Bergmann's rule.
• A common allometric pattern showed larger macaques have more elongated faces, but colder climates favored rounder faces.
• Prognathism correlated with diet, while localized facial shape variations linked to phylogenetic differences.

Conclusions:

• Climate and diet significantly shape macaque craniofacial morphology, independent of phylogenetic signals.
• The common allometric pattern, influenced by climate, complicates taxonomic interpretations of craniofacial traits.
• Allometric dissociation in macaques, driven by wide distributions, limits the taxonomic utility of craniofacial elongation.