Little hope for the polyploid endemic Pyrenean Larkspur (Delphinium montanum): Evidences from population genomics and Ecological Niche Modeling

Environmental gradients shape genetic variation in the desert moss, Syntrichia caninervis Mitt. (Pottiaceae)

The moss Syntrichia caninervis Mitt. is distributed throughout drylands globally, and often anchors ecologically significant communities known as biological soil crusts (biocrusts). The species occupies a variety of dryland habitats with varying levels of drought and temperature stress, suggesting the potential for ecological specialization within S. caninervis. Here, we sampled S. caninervis from sites along two elevation gradients and used restriction site associated DNA sequencing to compare the relative impacts of environmental factors and geospatial distances on genetic differentiation in S. caninervis populations. While we found no evidence of isolation by distance in our data, one environmental variable, mean annual precipitation (MAP), was found to be a positive predictor of FST. An ecological association analysis identified 32 SNP alleles that covary significantly with MAP, 15 of which fall within the exonic regions of genes with annotations suggesting diverse roles in response to dehydration stress. Understanding the degree to which genetic variation in S. caninervis is associated with environmental factors is key to predicting its potential for persistence in the face of global climate change, which is predicted to be especially detrimental to desert organisms already living at their physiological limits.

Karyotype and genome size variation in Delphinium subg. Anthriscifolium (Ranunculaceae)

Five taxa of Delphiniumsubg.Anthriscifolium have been karyologically studied through chromosome counting, chromosomal measurement, and karyotype symmetry. Each taxon that we investigated has a basic chromosome number of x = 8, D.anthriscifoliumvar.savatieri, D.anthriscifoliumvar.majus, D.ecalcaratum, and D.callichromum were diploid with 2n = 16, while D.anthriscifoliumvar.anthriscifolium was tetraploid with 2n = 32. Monoploid chromosome sets of the investigated diploid taxa contained 1 metacentric chromosome, 3 submetacentric chromosomes, and 4 subtelocentric chromosomes. Higher interchromosomal asymmetry (CVCL) was present in D.ecalcaratum and D.callichromum than in other taxa. The highest levels of intrachromosomal asymmetry (MCA) and heterogeneity in centromere position (CVCI) were found in D.anthriscifoliumvar.majus. Diploid and tetraploid genome sizes varied by 3.02-3.92 pg and 6.04-6.60 pg, respectively. Karyotype and genome size of D.anthriscifoliumvar.savatieri, D.anthriscifoliumvar.majus, D.callichromum, and D.ecalcaratum were reported for the first time. Finally, based on cytological and morphological data, the classification of Delphiniumanthriscifolium was revised.

The Conservation Genetics of Iris lacustris (Dwarf Lake Iris), a Great Lakes Endemic

Iris lacustris, a northern Great Lakes endemic, is a rare species known from 165 occurrences across Lakes Michigan and Huron in the United States and Canada. Due to multiple factors, including habitat loss, lack of seed dispersal, patterns of reproduction, and forest succession, the species is threatened. Early population genetic studies using isozymes and allozymes recovered no to limited genetic variation within the species. To better explore genetic variation across the geographic range of I. lacustris and to identify units for conservation, we used tunable Genotyping-by-Sequencing (tGBS) with 171 individuals across 24 populations from Michigan and Wisconsin, and because the species is polyploid, we filtered the single nucleotide polymorphism (SNP) matrices using polyRAD to recognize diploid and tetraploid loci. Based on multiple population genetic approaches, we resolved three to four population clusters that are geographically structured across the range of the species. The species migrated from west to east across its geographic range, and minimal genetic exchange has occurred among populations. Four units for conservation are recognized, but nine adaptive units were identified, providing evidence for local adaptation across the geographic range of the species. Population genetic analyses with all, diploid, and tetraploid loci recovered similar results, which suggests that methods may be robust to variation in ploidy level.

Characterization of the complete plastome of Delphinium montanum, a polyploid, endemic and endangered Pyrenean Larkspur

Delphinium montanum DC. 1815, is an endangered larkspur endemic to the Eastern Pyrenees. For biogeographic and conservation purpose, a hybrid assembly approach based on long- and short-read genomic data allowed us to successfully assemble whole plastid genome of Delphinium montanum. The complete plastome is 154,185 bp in length, consisting of a pair of inverted repeats (IRs) of 26,559 bp, a large single-copy (LSC) region and a small single-copy region (SSC) of 84,746 and 16,320 bp, respectively. It was found to contain 136 genes, including 84 protein-coding genes, 44 trRNA genes and 8 rRNA genes. The overall GC content of the plastid genome is 38.3%. Phylogenetic inference supports the polyphyly of the Delphinium genus.