Combining Historical and Ecological Methods Provides New Insights for the Recognition of Biogeographical Areas and Their Relationships: The Case of the Gulf of Mexico

ABSTRACT Aim Biogeographical regionalisation is an evolutionary system of nested areas representing the geographic organisation of life on the planet, which is fundamental for understanding basic and applied aspects related to the ecology, evolution and conservation of biotas and their habitats. The conceptual and practical development of biogeographical regionalisation has been diverse, deriving from two main subdisciplines: historical or evolutionary biogeography and ecological biogeography. This division has prevented the consolidation of an integrative discipline, hampering its advancement. In this work, we implement a new methodology for conducting biogeographical regionalisation by integrating two traditional techniques coming from historical and ecological biogeographical studies: parsimony analysis of endemicity and hierarchical clustering analysis into a coherent methodological framework (PAE‐HCA). Location Gulf of Mexico, Western Atlantic. Taxon Multi‐taxa. Methods The framework consists of three main steps: (1) identifying areas of distributional congruence, (2) establishing a spatial structure of the areas recognised and (3) recognising area relationships. The method includes the establishment of biogeographic hypotheses that can be tested statistically regarding the membership of the units that conform to each area and their affinity, providing robustness and biogeographic assertion. This methodological framework was tested with a comprehensive occurrence database from the Gulf of Mexico and adjacent waters. Results A total of 126 areas of distributional congruence were recovered, which were grouped into three main biogeographic areas with strong statistical support. These areas are congruent with geological and oceanographic features of the region, supporting the hypothesis that the Gulf can be divided into two main components, one characterised by neritic waters and the other characterised by oceanic waters. Main Conclusions The present study constitutes the first attempt to integrate historical and ecological techniques into a robust methodological framework. Future perspectives include implementing this approach in different environments, such as terrestrial, considering different geographic scales, including global studies, or different taxa.