ABSTRACT
Assessing the taxonomic status of closely related taxa is crucial in plant systematics and can have important implications for conservation and human plant use. Ericaandevalensis Cabezudo & Rivera is a metallophyte endemic species from highly metal-polluted soils of SW Iberian Peninsula, an area with a mining history going back more than 5,000 years. Ericaandevalensis is closely related to Ericamackayana Bab., a northern Iberian species also present in western Ireland. The status of E.andevalensis as a species or subspecies subordinated to E.mackayana is subject to debate. Here, we assessed the genetic and phenotypic relationship between both species, including the population structure of E.andevalensis. We used high throughput sequencing to determine genome-wide Single Nucleotide Polymorphisms (SNPs), and morphometric analyses from 35 reproductive and vegetative traits. The morphological analysis showed at least eight characters that can discriminate the two species, from which ovary hairiness and the size of leaf glandular hairs were the most informative. Genetic analyses showed that each species formed a monophyletic cluster with full support, separated by an interspecific genetic distance >4-fold higher than intra-specific distance. Population genetic analyses of E.andevalensis shows that populations are highly structured, with the Portuguese one as the most isolated and less variable. These results support the recognition of E.andevalensis as a distinct species with a highly constrained ecological requirements and a narrow geographic distribution, but with a limited gene flow between populations. We discuss the implications of these outcomes in conservation policies and potential uses of E.andevalensis such as decontamination of polluted soils.
ABSTRACT
Molecular analyses, in combination with morphological studies, provide invaluable tools for delineating red algal taxa. However, molecular datasets are incomplete and taxonomic revisions are often required once additional species or populations are sequenced. The small red alga Conferva parasitica was described from the British Isles in 1762 and then reported from other parts of Europe. Conferva parasitica was traditionally included in the genus Pterosiphonia (type species P. cloiophylla in Schmitz and Falkenberg 1897), based on its morphological characters, and later transferred to Symphyocladia and finally to Symphyocladiella using molecular data from an Iberian specimen. However, although morphological differences have been observed between specimens of Symphyocladiella parasitica from northern and southern Europe they have yet to be investigated in a phylogenetic context. In this study, we collected specimens from both regions, studied their morphology and analyzed rbcL and cox1 DNA sequences. We determined the phylogenetic position of a British specimen using a phylogenomic approach based on mitochondrial and plastid genomes. Northern and southern European populations attributed to S. parasitica represent different species. Symphyocladiella arecina sp. nov. is proposed for specimens from southern Europe, but British specimens were resolved as a distant sister lineage to the morphologically distinctive Amplisiphonia, so we propose the new genus Deltalsia for this species. Our study highlights the relevance of using materials collected close to the type localities for taxonomic reassessments, and showcases the utility of genome-based phylogenies for resolving classification issues in the red algae.
