Reconciling patterns of phylogenetic rate heterogeneity in ferns with morphology, ecology, and life history

NSF CAREER award 0347840 to Kathleen Pryer

This research aims to infer a comprehensive phylogenetic estimate of relationships among all fern families using an 82 taxon x 8-gene data set, with DNA sequence data spanning all three genomes (chloroplast, nuclear, and mitochondrial). This phylogeny will culminate in a more stable classification that will be made publicly available as a Fern Phylogeny website.

We have detected multiple independent cases of drastic switches in rates of evolution among and within major fern lineages, making ferns an ideal group to study the causes and consequences of such evolutionary shifts. This research is critically examining phylogenetic rate heterogeneity in chloroplast genes across fern lineages. This rate heterogeneity phenomenon demands explanation and provides an outstanding opportunity to move "beyond the phylogeny" by integrating various methodological approaches that not only seek to explain these molecular rate differences in the chloroplast genome, but to determine if this is a generalized pattern also present in the nuclear and mitochondrial genomes, and to attempt to interpret why we see these rate differences, within the context of the biology of these ferns (their morphology, ecology, and life history patterns).

This study is a highly integrated attempt to interpret molecular rate differences within the context of the biology of these ferns by: focusing on three target groups of leptosporangiate ferns in detail (filmy ferns, pteridoid ferns, and tree ferns); by considering fine-scale morphological, ecological and life history patterns that may correlate with these observed rate differences and that perhaps have impacted fern diversification; and by integrating various methodological approaches.

COLLECTIONS | Vascular Plants | Algae | Bryophytes | Fungi | Lichens

Duke University Herbarium