SG: Phylogenomics, chromosome evolution, and diversification of the sundews, a group of carnivorous plants

The sundews (Drosera) are approximately 250 species of carnivorous plants distributed worldwide, with most species found in warm temperate and tropical regions. The plants' ability to catch and digest insect prey has long fascinated the public as well as botanists. In addition to these plants' unusual method of acquiring nutrients, sundews also appear to possess striking variation in chromosome number and structure, but large-scale surveys are lacking owing to the need for living organisms and advanced microscopy techniques to evaluate these features. This project will take advantage of extensive living collections of sundews available to the researchers, as well as targeted collecting efforts, to survey the chromosome numbers and genome size of numerous sundew species, as well as the environmental conditions in which the plants grow. Researchers will also reconstruct the evolutionary history of the sundews using phylogenomic data, allowing them to evaluate the history of chromosome evolution and habitat specialization in this group and their role in driving diversification. This project will provide research training for undergraduate and graduate students and will enable the development of collaborations for an early-career researcher. In addition, the researchers will deliver hands-on educational modules for first-year undergraduate students and K-12 students. They will also assemble a living collection of sundews that will be available through the College of Biological Sciences Conservatory at the University of Minnesota for research, teaching, and public access.

A multi-layered dataset will be generated for reconstructing the history of chromosomal evolution of the sundews and to test the macroevolutionary link between chromosome number variation and lineage diversification. Species relationships will be estimated by sampling at least 80% of the 250 species in the genus using a combination of transcriptome and Hyb-Seq data. Chromosome number and genome size data will be obtained for at least 40% of sundew species, and immunostaining will be used to determine the centromere type, which is thought to vary substantially in Drosera, in 15 species across the genus. Additionally, species occurrence data will be compiled from publicly available specimen databases to enable reconstruction of climatic niche and soil characteristics. The researchers will use state-of-the-art methods in phylogenomic data analysis to model chromosome changes, combined with sampling hundreds of genes across the genome to determine the placement of whole genome duplication and single chromosome gain and loss events. This project will not only enable subsequent investigations into the mechanisms of chromosome evolution in sundews, but it will also establish a rigorous analytical framework for comparative analyses of chromosome evolution across the tree of life.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.