Hormones and body size evolution in papionin primates

Area of Science:

• Primate evolutionary biology
• Endocrinology
• Comparative genomics

Background:

• Papionin primates exhibit significant body size variation.
• Hormones like IGF-I and testosterone are known to regulate growth and size.
• Previous research suggests a link between hormone levels and body size.

Purpose of the Study:

• To investigate the relationship between circulating hormone levels and body size evolution in papionins.
• To determine if similar hormone profiles underlie convergent evolution of large body size in papionins.
• To test if hormone levels covary with body size during growth and in adulthood across species.

Main Methods:

• Analysis of serum samples from 161 individuals across 11 papionin species.
• Measurement of key growth-related hormones: IGF-I, IGFBP-3, GHBP, DHEAS, testosterone, and estradiol.
• A two-level approach: mixed longitudinal analysis within species and cross-species comparison.

Main Results:

• Circulating hormone levels did not consistently covary with body size across papionins, either during growth or in adulthood.
• Some smaller-bodied papionin species exhibited higher absolute hormone levels than larger-bodied species.
• Hormone level differences appeared to correlate more closely with phylogeny than with body size.

Conclusions:

• Absolute circulating hormone levels may be decoupled from interspecific differences in body size in papionins.
• Hormonal regulation of growth does not consistently explain the evolution of body size diversity and convergence in this primate group.
• Phylogenetic history may play a more significant role than hormone levels in shaping body size differences across papionin species.