Variation and macroevolution in leaf functional traits in the Hawaiian silversword alliance (Asteraceae)

The Hawaiian silversword alliance is a spectacular example of plant adaptive radiation. The lineage includes 33 species in three endemic genera (Argyroxiphium, Dubautia and Wilkesia) that occupy almost all major habitats of the Hawaiian archipelago. Here, we quantitatively explore functional diversification in the lineage by linking measurements of multiple leaf functional traits with climate niche and phylogenetic data. We show that leaf functional trait variation (i) spans much of the global angiosperm range, (ii) is best explained by a white-noise evolutionary model and (iii) is integrated in ways consistent with both the global leaf economics spectrum and the predictions of leaf venation network theory. Our results highlight the importance of functional diversification and integration in rapidly evolving plant lineages. They also provide compelling additional support for the view that the Hawaiian silversword alliance is one of the world's premier examples of adaptive radiation in plants. The Hawaiian silversword alliance includes 33 species in three endemic genera (Argyroxiphium, Dubautia, and Wilkesia) that occupy almost all major habitats of the Hawaiian archipelago (top row). We show that leaf functional trait variation in the lineage spans much of the global angiosperm range, is best explained by a white-noise evolutionary model, and is integrated in ways consistent with both the global leaf economics spectrum and the predictions of leaf venation network theory (bottom row). The results provide compelling support for the view that the silversword alliance is one of the world's premier examples of adaptive radiation in plants. Journal of Ecolog

The Plant Proteome Folding Project: Structure and Positive Selection in Plant Protein Families Genome Biology and Evolution Advance Downloaded from

ABSTRACT Despite its importance, relatively little is known about the relationship between the structure, function and evolution of proteins, particularly in land plant species. We have developed a database with predicted protein domains for five plant proteomes (http://pfp.bio.nyu.edu), and used both protein structural fold-recognition and de novo Rosettabased protein structure prediction to predict protein structure for Arabidopsis and rice proteins. Based on sequence similarity, we have identified ~15,000 orthologous/paralogous protein family clusters among these species, and used codon-based models to predict positive selection in protein evolution within 175 of these sequence clusters. Our results show that codons that display positive selection appears to be less frequent in helical and strand regions, and are overrepresented in amino acid residues that are associated with a change in protein secondary structure. Like in other organisms, disordered protein regions also appear to have more selected sites. Structural information provides new functional insights into specific plant proteins and allows us to map positively selected amino acid sites onto protein structures and view these sites in a structural and functional context

Natural variation in plant telomere length is associated with flowering time

Telomeres are highly repetitive DNA sequences found at the ends of chromosomes that protect the chromosomes from deterioration duringcell division. Here, using whole-genome re-sequencing and terminal restriction fragment assays, we found substantial natural intraspecific variation in telomere length in Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays). Genome-wide association study (GWAS) mapping in A. thaliana identified 13 regions with GWAS-significant associations underlying telomere length variation, including a region that harbors the telomerase reverse transcriptase (TERT) gene. Population genomic analysis provided evidence for a selective sweep at the TERT region associated with longer telomeres. We found that telomere length is negatively correlated with flowering time variation not only in A. thaliana, but also in maize and rice, indicating a link between life-history traits and chromosome integrity. Our results point to several possible reasons for this correlation, including the possibility that longer telomeres may be more adaptive in plants that have faster developmental rates (and therefore flower earlier). Our work suggests that chromosomal structure itself might be an adaptive trait associated with plant life-history strategies