Accounting for Chimerism in Demographic Inference: Reconstructing the History of Common Marmosets (Callithrix...

Area of Science:

• Evolutionary biology
• Genomics
• Primate research

Background:

• The common marmoset (Callithrix jacchus) is a key biomedical model species.
• Unique reproductive and developmental traits (twin births, chimerism) complicate population genetic analyses.
• Existing demographic inference methods may yield inaccurate results for this species.

Purpose of the Study:

• To investigate the impact of twin births and chimerism on demographic inference in common marmosets.
• To develop a novel statistical approach for accurate population genomic modeling in Callithrix jacchus.
• To reconstruct the demographic history of the common marmoset population.

Main Methods:

• Simulations to assess the effects of neglecting twin births and chimerism.
• Development of a novel approximate Bayesian inference framework.
• High-coverage sequencing of 15 common marmoset individuals.
• Identification of neutrally evolving intergenic regions using gene annotations.

Main Results:

• Neglecting twin births and chimerism leads to significant mis-inference of population history.
• The novel Bayesian method accurately models demographic history.
• Estimated robust ancestral and current population sizes.
• Identified a population size reduction approximately 7,000 years ago.

Conclusions:

• Accurate demographic inference for common marmosets necessitates accounting for twin births and chimerism.
• The developed methodology provides a robust framework for studying marmoset population genomics.
• The population size reduction may correlate with environmental changes in north-eastern Brazil.