Species delimitation and geography

Area of Science:

• Evolutionary Biology
• Population Genetics
• Biodiversity Science

Background:

• Species delimitation is crucial for understanding biodiversity but is challenged by spatial population structures.
• Integrating geographical information into species delimitation is limited, especially for allopatric populations.
• Assessing genetic divergence in allopatric populations requires robust methods to infer species boundaries.

Purpose of the Study:

• To propose a novel statistical approach for species delimitation that incorporates spatial information.
• To test the hypothesis that genetic distances between candidate species align with geographical distances.
• To provide a method for distinguishing between intra- and interspecific genetic differentiation.

Main Methods:

• Developed a regression-based approach to test the relationship between genetic and geographical distances.
• Proposed a null hypothesis: genetic distances between candidate species are not greater than expected based on their geographical separation.
• Compared the proposed method with (partial) Mantel tests for assessing isolation by distance.

Main Results:

• The novel approach effectively distinguishes between intra- and interspecific differentiation in case studies.
• The regression method is more suitable than Mantel tests for evaluating species hypotheses related to isolation by distance.
• The method's assumption of a linear relationship between genetic and geographical distances can be affected by high within-population genetic variability.

Conclusions:

• The proposed method offers a robust framework for species delimitation by integrating spatial genetic data.
• This approach enhances the accuracy of species boundary inference, particularly for allopatric populations.
• The study highlights the importance of considering geographical context in genetic divergence analyses for species status.