A model of immunological distances in systematics

Area of Science:

• Systematics
• Immunology
• Phylogenetics

Background:

• Immunological distances are widely used in systematics.
• Concerns exist regarding their non-metric nature, specifically non-reciprocity and violation of triangle inequality.
• This non-metricity questions their utility in phylogenetic analysis.

Purpose of the Study:

• To present a model relating observed immunological distance to antigenic site differences.
• To develop procedures for transforming non-metric immunological distances into metric distances.
• To address scaling and non-reciprocity issues in distance matrices for improved phylogenetic inference.

Main Methods:

• A mathematical model was developed to link immunological distance with antigenic site differences.
• Two transformation procedures were proposed to convert immunological distances to metric distances.
• An extension of the ADCLUS procedure was suggested for further data transformation.

Main Results:

• The model explains departures from metric conditions (reciprocity, triangle inequality).
• Standard scaling adjustments for immunological distance matrices were found inappropriate.
• A proposed transformation is effective for similarity matrices, but non-reciprocity remains a challenge.

Conclusions:

• The developed model and transformations offer a strategy to derive metric distances from non-metric immunological data.
• This approach enhances the utility of immunological data for robust phylogenetic reconstruction.
• Further methodological extensions are suggested to fully address non-metricity issues.