Incorporating the speciation process into species delimitation

Area of Science:

• Evolutionary Biology
• Genomics
• Systematics

Background:

• The multispecies coalescent (MSC) model is widely used for species delimitation but struggles to differentiate between genetic structure within species and distinct species.
• Increasing genomic and spatial data resolution exacerbates this issue, leading to artifactual species identification due to population-level gene flow restrictions.

Purpose of the Study:

• To introduce a novel approach for species delimitation that overcomes limitations of the MSC model.
• To develop a method that explicitly models the speciation process, distinguishing between population lineages and species formation.

Main Methods:

• Developed an extended speciation process model for species delimitation.
• Modeled the formation of population lineages and their subsequent divergence into species as separate processes.
• Incorporated existing knowledge of species boundaries by specifying identities for a subset of lineages.

Main Results:

• Successfully discriminated between species boundaries and within-species lineage boundaries.
• Assigned species identities to lineages with unknown affinities using quantified probabilities.
• Provided insights into the links between population and species-level evolutionary processes.

Conclusions:

• The new approach enhances the accuracy of species delimitation by separating population and species-level genetic structure.
• Explicitly modeling speciation and gene flow restrictions provides a more robust framework for understanding evolutionary dynamics.
• Genetic data, when integrated with other information within this new framework, can reveal not only species boundaries but also the tempo of speciation.