Evolution and biogeography of the endemic Roucela complex (Campanulaceae: Campanula) in the Eastern Mediterranean

At the intersection of geological activity, climatic fluctuations, and human pressure, the Mediterranean Basin – a hotspot of biodiversity – provides an ideal setting for studying endemism, evolution, and biogeography. Here, we focus on the Roucela complex (Campanula subgenus Roucela), a group of 13 bellflower species found primarily in the eastern Mediterranean Basin. Plastid and low-copy nuclear markers were employed to reconstruct evolutionary relationships and estimate divergence times within the Roucela complex using both concatenation and species tree analyses. Niche modeling, ancestral range estimation, and diversification analyses were conducted to provide further insights into patterns of endemism and diversification through time. Diversification of the Roucela clade appears to have been primarily the result of vicariance driven by the breakup of an ancient landmass. We found geologic events such as the formation of the mid-Aegean trench and the Messinian Salinity Crisis to be historically important in the evolutionary history of this group. Contrary to numerous past studies, the onset of the Mediterranean climate has not promoted diversification in the Roucela complex and, in fact, may be negatively affecting these species. This study highlights the diversity and complexity of historical processes driving plant evolution in the Mediterranean Basin

An Exploration into Fern Genome Space

Ferns are one of the few remaining major clades of land plants for which a complete genome sequence is lacking. Knowledge of genome space in ferns will enable broad-­‐scale comparative analyses of land plant genes and genomes, provide insights into genome evolution across green plants, and shed light on genetic and genomic features that characterize ferns, such as their high chromosome numbers and large genome sizes. As part of an initial exploration into fern genome space, we used a whole genome shotgun sequencing approach to obtain low-­‐density coverage (~0.4X to 2X) for six fern species from the Polypodiales (Ceratopteris, Pteridium, Polypodium, Cystopteris), Cyatheales (Plagiogyria), and Gleicheniales (Dipteris). We explore these data to characterize the proportion of the nuclear genome represented by repetitive sequences (including DNA transposons, retrotransposons, rDNA, and simple repeats) and protein-­‐coding genes, and to extract chloroplast and mitochondrial genome sequences. Such initial sweeps of fern genomes can provide information useful for selecting a promising candidate fern species for whole genome sequencing. We also describe variation of genomic traits across our sample and highlight some differences and similarities in repeat structure between ferns and seed plants

Defining Populations and Predicting Future Suitable Niche Space in the Geographically Disjunct, Narrowly Endemic Leafy Prairie-Clover (<i>Dalea foliosa</i>; Fabaceae)

Conservation actions for rare species are often based on estimates of population size and number, which are challenging to capture in natural systems. Instead, many definitions of populations rely on arbitrarily defined distances between occurrences, which is not necessarily biologically meaningful despite having utility from a conservation management perspective. Here, we introduce a case study using the narrowly endemic and highly geographically disjunct leafy prairie-clover (Dalea foliosa), for which we use nuclear microsatellite loci to assess the current delimitations of populations and management units across its entire known range. We model future potential suitable niche space for the species to assess how currently defined populations could fare under predicted changes in climate over the next 50 years. Our results indicate that genetic variation within the species is extremely limited, particularly so in the distal portions of its range (Illinois and Alabama). Within the core of its range (Tennessee), genetic structure is not consistent with populations as currently defined. Our models indicate that predicted suitable niche space may only marginally overlap with the geology associated with this species (limestone glades and dolomite prairies) by 2070. Additional studies are needed to evaluate the extent to which populations are ecologically adapted to local environments and what role this could play in future translocation efforts

Binary suitability prediction for California Heuchera MRCA: Last Glacial Maximum, wide-buffer models

This is the suitability prediction for the MRCA of the California Heuchera clade (Heuchera caespitosa, Heuchera abramsii, Heuchera elegans, Heuchera parishii, Heuchera hirsutissima) for the Last Glacial Maximum (22k years ago), using wide-buffer models and binary maps

Ancestral reconstruction -- distance-buffer models

Ancestral reconstruction results (point estimates and credibility intervals) for distance-buffer models. This is in BEAST-compatible NEXUS format and can be read by FigTree

Binary suitability prediction for Mitella MRCA: Last Glacial Maximum, distance-buffer models

This is the suitability prediction for the MRCA of Mitella s.s. (Mitella nuda + Mitella diphylla) for the Last Glacial Maximum (22k years ago), using distance-buffer models and binary maps

BEAST dating analysis -- nuclear data, truncated normal prior

BEAST analysis of the nuclear genes with a truncated normal calibration prior. For analytical details see the manuscript. Tip labels for all taxa newly sampled in this analysis, Linnaean binomials were used. For all taxa sampled in previous work, sample codes were used to match voucher references in other works; for these refer to Folk et al., Systematic Biology, 66(3): 320–337; refer also to the associated Dryad deposition, https://doi.org/10.5061/dryad.cd546 (in which see Online Appendix 1)

BEAST dating analysis -- nuclear data, lognormal prior

BEAST analysis of the nuclear genes with a lognormal calibration prior. For analytical details see the manuscript. Tip labels for all taxa newly sampled in this analysis, Linnaean binomials were used. For all taxa sampled in previous work, sample codes were used to match voucher references in other works; for these refer to Folk et al., Systematic Biology, 66(3): 320–337; refer also to the associated Dryad deposition, https://doi.org/10.5061/dryad.cd546 (in which see Online Appendix 1)

Binned-probabilities suitability prediction for Mitella MRCA: Last Glacial Maximum, narrow-buffer models

This is the suitability prediction for the MRCA of Mitella s.s. (Mitella nuda + Mitella diphylla) for the Last Glacial Maximum (22k years ago), using narrow-buffer models and normalized binned-probabilities maps