Latitudinal variation in cranial dimorphism in Macaca fascicularis

Area of Science:

• Primatology
• Evolutionary Biology
• Morphometrics

Background:

• Sexual dimorphism, the difference in size or appearance between sexes, is common in primates.
• Cranial length dimorphism (CLD) is a key trait studied in primate evolution.
• Understanding geographic variation in CLD is crucial for evolutionary insights.

Purpose of the Study:

• To investigate latitudinal and insular variation in CLD in Macaca fascicularis.
• To examine the relationship between CLD and sex-specific size across different geographic groups.
• To identify factors influencing CLD patterns in this primate species.

Main Methods:

• Analysis of cranial length data from three distinct geographical groupings of Macaca fascicularis.
• Statistical examination of the correlation between CLD and latitude.
• Assessment of sex-specific relationships between cranial length and CLD.

Main Results:

• A significant relationship between CLD and latitude was found in only one of the three geographic groupings.
• Sex-specific relationships between cranial length and CLD were identified.
• The patterns of these relationships differed across the geographic groupings, indicating significant variability.

Conclusions:

• Despite similar overall CLD levels, Macaca fascicularis exhibits substantial geographic variability in the factors associated with this dimorphism.
• Geographically varying ecological factors likely influence sex-specific natural selection and the intensity of CLD.
• Future research should integrate ecological and social contexts with morphological variation to understand CLD patterns.