A classification of structured-coalescent processes with migration, conditional on the population pedigree

Area of Science:

• Population genetics
• Evolutionary biology
• Statistical genetics

Background:

• Organismal genealogies (pedigrees) influence population variation and coalescence times.
• Traditional coalescent models often marginalize over population pedigrees.
• Understanding pedigree effects is vital for accurate genetic inference in structured populations.

Purpose of the Study:

• To extend analyses of pedigree effects on common ancestry to populations with subdivision and migration.
• To investigate how population structure and migration patterns interact with pedigree effects.
• To determine when traditional coalescent models are insufficient due to pedigree influences.

Main Methods:

• Conditioning analyses on the population pedigree, contrasting with traditional models that marginalize over it.
• Applying a test based on the distribution of pairwise coalescence times.
• Simulations and numerical analysis to illustrate findings across various subdivision and migration scenarios.

Main Results:

• Pedigree effects were found in three out of four tested scenarios of population subdivision and migration.
• The pedigree effect was weak when deme sizes were large in most cases.
• A persistent pedigree effect was observed in scenarios with infrequent migration pulses, even with large deme sizes.

Conclusions:

• Data analysis and interpretation in structured populations require coalescent models conditioned on the pedigree, not just traditional models.
• The structured-coalescent model may be applicable to multiple unlinked loci.
• Pedigrees must be considered in statistical genetic inference, particularly when deme sizes are not large or gene flow is intermittent.