Assessing the role of polyploidy evolution on diversification rates in a species-rich lineage of the pineapple family

• Applicant: Professor Dr. Stefan Wanke
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546888221

Polyploidy, the duplication of whole chromosome sets can promote ecological differentiation, phenotypic changes, affect recombination rates, gene expression, and might lead to reproductive isolation of lineages. However, whether polyploidy has a differential impact on diversification rates is still a major question in plant evolutionary biology. Polyploidization is known to have occurred during the evolution of seed plants. Contrasting evidence argues in favor or against polyploidization leading to increases in diversification rates at shallower evolutionary depths such as at or below the family level. Modeling the influence of polyploidy on diversification, i.e. trait-dependent diversification, requires knowledge on the ploidy level (herein diploid vs. polyploid) and an appropriately sampled phylogenetic context. Although data on chromosome numbers have been compiled in readily accessible public databases, this information remains limited for species-rich lineages. Also, trait-dependent diversification models testing the role of single traits on diversification do not accommodate the possibility that additional, unobserved or explicit traits might better explain the diversification pattern. Finally, incomplete sampling of taxa, which is common in highly diverse lineages and expected given our inability to sample all (extinct) taxa, might impact diversification analyses. In this project we will address the above challenges by combining advances in next-generation sequencing techniques, recently developed bioinformatic and analytical methods, and cytogenetics. We focus on shallow evolutionary scales within the megadiverse, Neotropical genus Tillandsia (ca. 792 spp.) of the pineapple family (Bromeliaceae; >3,500 spp.), an excellent model system owing to its remarkable species diversity and varied morphological and physiological adaptations. Our focal group is Tillandsia subgenus Tillandsia, a highly diverse lineage (ca. 290 spp.) recently proposed to have experienced an explosive radiation fueled by extensive hybridization and in which yet masked (allo)polyploid diversity is likely to be uncovered. We will test the central hypothesis that diversification rates vary as a function of polyploidy evolution. Our proposal builds on a significant amount of preliminary data (e.g. ca. 35% of the species of the focal group have already been sequenced), nearly fully established bioinformatic pipelines, and the expertise of our international team of plant evolutionary biologist.

• DFG Programme: Research Grants
• International Connection: Mexico
• Partner Organisation: Universidad Nacional Autónoma de México (UNAM)
• Cooperation Partner: Professorin Dr. Carolina Granados Mendoza