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Taxus baccata is a relic-declining species, especially at the southern edge of its natural distribution. On the Island of Sardinia, we found 237 locations where yews grow, being indifferent to substrates, preferring moist sites with northern aspects and with an elevation range of 695–1,225 m a.s.l. We applied the Maximum Entropy algorithm (MaxEnt), using 202 field-based sites and 19 bioclimatic variables, to model the present potential distribution. Our model showed high levels of predictive performances with significant values of AUC (training, 0.962; test, 0.963). Annual precipitation, mean temperature of the warmest month and isothermality were the key drivers for the distribution of yew in Sardinia. The response curves showed that T. baccata prefers annual mean temperatures ranging from 8.65 to 12.55 °C and annual mean precipitation from 770 to 1,085 mm. Most potential suitable conditions were found in northern and central Sardinia. We also modelled future habitat suitability for T. baccata under two different scenarios (ssp245 and ssp585), highlighting a predicted drastic reduction, up to >95% in the worst scenario, of the habitat suitability for yews by the end of this century. This is related to climate change and poses increasing concerns about the future of yews in Sardinia. [ABSTRACT FROM AUTHOR]

Gastridium P. Beauv. is a Mediterranean-Paleotropical member of the Poaceae family, whose species number and diversity are still imperfectly known. We examined patterns of DNA diversity at two plastid (trnH-psbA, trnL-F) and one nuclear (ITS) DNA markers in 44 individuals of the four taxa (Gastridium lainzii, G. phleoides, G. scabrum, G. ventricosum) recently recognised by different authors, based on morpho-ecological descriptors. Diversity data were explored with multiple statistical and phylogenetic tools, and integrated with available GenBank sequences of Gastridium and closely related genera. Despite the limited variability detected, evidence of within-taxon genetic cohesion and estimates of molecular divergence comparable with those of species in the same subtribal lineage (Agrostidinae) were recovered. The identified plastid genealogies are congruent with a subdivision of the genus into four distinct species, coherently with collected morphological descriptors. Phylogenetic reconstructions with ITS were less corresponding to the four taxa, possibly due to reticulation and polyploidization. The broader plastid and nuclear tree topologies were consistent with previous assessments, highlighting the overall little resolution of species and genera within Agrostidinae, and the close relationships shared by Gastridium and Triplachne. The hypothesis of closely related, but separately evolving, lineages within Gastridium is discussed, suggesting a re-evaluation of its current taxonomy. [ABSTRACT FROM AUTHOR]