Novel Insights Into Refugia at the Southern Margin of the Distribution Range of the Endangered Species Ulmus laevis

Abstract

Riparian ecosystems, in long-time developed regions, are among the most heavily impacted by human activities; therefore, the distribution of tree riparian species, such as Ulmus laevis, is highly affected. This phenomenon is particularly relevant at the margins of the natural habitat of the species, where populations are small and rare. In these cases, it is difficult to distinguish between relics or introductions, but it is relevant for the restoration of natural habitats and conservation strategies. The aim of this study was to study the phylogeography of the southern distribution of the species. We sequenced the entire chloroplast (cp) genomes of 54 individuals from five sampled populations across different European regions to highlight polymorphisms and analyze their distribution. Thirty-two haplotypes were identified. All the sampled populations showed private haplotypes that can be considered an indicator of long-term residency, given the low mutation rate of organellar DNA. The network of all haplotypes showed a star-like topology, and Serbian haplotypes were present in all branches. The Balkan population showed the highest level of nucleotide and genetic diversity. Low genetic differentiation between populations was observed but we found a significant differentiation among Serbia vs. other provenances. Our estimates of divergent time of U. laevis samples highlight the early split of above all Serbian individuals from other populations, emphasizing the reservoir role of white elm genetic diversity of Serbian population.

Insights into the phylogeny and chloroplast genome evolution of Eriocaulon (Eriocaulaceae)

“…For example, chloroplast genome data had resolved the systematic positions of enigmatic taxa in Saxifragales [37] and shed lights on the intergeneric relationships and spatio-temporal evolutionary history of Melocanninae (Poaceae) [36]. Moreover, the chloroplast genome sequences showed variations at the intraspecies levels, and revealed the genetic difference and diversity of endangered species [38,39] and cultivated species [40,41].…”

Notulae to the Italian native vascular flora: 14

“…Ulmus laevis is considered by Bartolucci et al (2018) as a cryptogenic species in Piemonte and as naturalized alien elsewhere in Italy. As recently proposed by Torre et al (2022), the native and relictual presence of the species in Piemonte and Lombardia has been definitely proven. The presence of U. laevis in alluvial woods along the Dora Baltea river is documented in Piemonte (R. Benetti and A. Selvaggi, pers.…”

Genomic divergence and demographic history of Quercus aliena populations

“…Chloroplast genomes are less commonly used at the intraspecies level owing to less polymorphism in practice [ 19 , 26 , 27 ]. However, with the advent of NGS sequencing methods, whole chloroplast genomes have been sequenced and used in population studies, such as of the medicinal plants Arnebia euchroma and Arnebia guttata [ 28 ], the endangered species Ulmus laevis [ 29 ] and Bretschneidera sinensis [ 30 ], the fruit tree Ziziphus jujuba [ 31 ], and the ornamental plants Aquilegia ecalcarata [ 15 ] and Lagerstroemia indica [ 32 ]. These findings suggest that chloroplast genome sequences contain many SNPs and indels suitable for genetic diversity and phylogeography studies.…”