Work during the project has concentrated on four fronts: (1) compiling a database with taxonomic descriptions and reclassifications of tropical plants, (2) performing quality checks on the data compiled, (3) documenting the timeline of taxonomic changes, and (4) analysing temporal and geographic trends in species description and reclassifications. The project was carried out at the Spanish Natural Science Museum (MNCN-CSIC; hosting institution) the and University of Luxembourg (Secondment)
Database: As of June 2022, the database T4-DB contains bibliographic information and the timeline of nomenclatural changes for 3 935 taxa belonging to the families Arecaceae, Lecythidaceae (Amazon rainforest) or the clade Bignonieae (Neotropics). For Bignonieae, we added detailed information about attributes of species descriptions, whereas for Arecaceae we added information about characteristics (e.g. functional traits and phylogenetic. The database (Arecaceae, Lecythidaceae, Bignonieae) will be made publicly available via Digital CSIC upon publications derived from TAXON-TIME (Stropp et al. in prep. and Meyer et al. in prep).
Results: The database compiled by TAXON-TIME provided the basis for quantifying the contribution of taxonomic change to established patterns of species richness and composition of tropical rainforests. Two analyses on subsets of this database (Bignonieae and Arecaceae) reveal that 78% of all descriptions of Neotropical Bignonieae (Bignonieae) proposed taxa names that later became synonyms, while for Amazonian palms (Arecaceae) the share of synonyms is 85%. Synonymizations were crucial for shaping the current pattern of species richness and composition. For Bignonieae, the well-documented pattern of species richness, i.e. high richness in the Amazon and the Atlantic forests decreasing towards central South America and the subtropical region, is only observed due to past taxonomic changes (Meyer et al. in prep.). For Amazonian palms, the established geographical pattern of changes in species composition, which stretches from northeast Amazonia to the southeast portion of the Brazilian Amazon also only emerges as a result of taxonomic changes that occurred mainly after the 1990s (Stropp et al. in prep). Together, these results show that progress in taxonomy can modify the observed correlations between different aspects of biodiversity (e.g. species richness and composition) and environmental factors, such as climate or soil fertility.
Finally, TAXON-TIME results show that synonymization is not random across taxa. In fact, synonyms are more frequent in earlier described taxa, in taxa that were subject to intensive taxonomic investigation and those with large geographical ranges.
TAXON-TIME will continue to expand the database documenting taxonomic changes of tropical plants to include other plant groups. Thanks to an 18-month extension of this MSCA action funded by the Spanish National Research Council, the fellow will proceed with her studies on the impact of taxonomic progress on macroecological patterns of tropical plants.
