In apomictic genus, conservation planning is undermined by taxonomic complexity. The Limonium confusum aggregate is a taxonomically complex group of Mediterranean coastal plant species. Morphological criteria alone are insufficient to distinguish its members, complicating conservation efforts in a context of habitat degradation. The aggregate includes Limonium confusum, Limonium cuspidatum, Limonium densissimum, and Limonium legrandii, four taxa with overlapping distributions and unclear delimitation. To design conservation targets that respect the evolutionary legacy of this Limonium aggregate, we sampled all known populations of the four taxa with the aim of delimiting Evolutionary Significant Units (ESUs). The screening of 305 genotypes from 30 populations by 12 nuclear microsatellite markers identified 23 multilocus genotypes, grouped into three distinct clusters, challenging current taxonomy. Populations genetic diversity screening, as well as a progeny analysis, support the absence of genetic admixture within or between these clusters, even in sympatry, which is explained by apomictic reproduction. Each genetic cluster form a unique lineage with geographic and ecological patterns indicating that they deserve to be considered as ESUs. The first ESUs is endemic to the French Languedoc region. The second ESU has a scattered distribution in France and is associated with rocky habitats such as coastal cliffs and limestone plateaus. The third ESU exhibits a disjunct distribution: a first group of populations are distributed along the Iberian coasts of Valencia and Castellón and a second range in the French regions of Camargue and Provence. The results underline the importance of phylogeography studies conducted across taxonomic and geographical boundaries for conservation planning of apomictic species complexes.
Mediterranean coastal habitats and the biotic communities they harbor face a variety of threats and their conservation is a global priority. Reintroductions are an effective tool to reverse wild plant population declines, and seed banks can supply the plant material required for these activities. Without accurate knowledge of what species are available at local seed banks, planning and performing reintroductions may be a challenge. In this study, we assessed the seed banking status of the characteristic species of target Mediterranean coastal habitats across 28 European and extra-European seed banks of the Mediterranean biogeographic region and answered the following questions: (1) how many accessions of the target species are currently banked? and (2) what has been the trend of seed collection for the target species in the last 50 years? We found that only half of the target species are stored in at least one seed bank, with many occurring in one seed bank as a single accession; for less than half of the target species, the surveyed seed banks had access to a propagation protocol; only 10
L’étude des plantes vasculaires introduites par les humains hors de leur aire de répartition naturelle a généré une terminologie très prolifique qui est souvent devenue absconse et inutilement complexe. Durant les dernières décennies, l’écologie des invasions a cherché, au contraire, à replacer les processus d’introduction, de naturalisation et d’invasion des taxons au sein d’un cadre théorique unifié. Dès lors, la terminologie qui décrit le statut d’un taxon le long de la séquence introduction-naturalisation-invasion peut être clarifiée et simplifiée. Dans le cadre du projet d’inventaire des plantes vasculaires exogènes de France hexagonale, nous proposons de moderniser et d’harmoniser la terminologie française avec celle de la littérature internationale en se fondant, autant que possible, sur des processus écologiques. Ce travail a conduit à approfondir des notions telles que néotaxon, ainsi qu’à préciser le sens de « plante invasive » et de « plante exotique envahissante » en fonction des abondances locale (au niveau d’une population) et régionale (au niveau d’un territoire) et de la prise en compte ou non de leurs impacts. Une terminologie clarifiée devrait aussi permettre aux gestionnaires de mieux cibler et optimiser leurs stratégies de gestion.
Ongoing global warming and increasing drought frequencies impact plant populations and potentially drive rapid evolutionary adaptations. Historical comparisons, where plants grown from seeds collected in the past are compared to plants grown from freshly collected seeds from populations of the same sites, are a powerful method to investigate recent evolutionary changes across many taxa. We used 21–38 years old seeds of 13 European plant species, stored in seed banks and originating from Mediterranean and temperate regions, together with recently collected seeds from the same sites for a greenhouse experiment to investigate shifts in flowering phenology as a potential result of adaptive evolution to changes in drought intensities over the last decades. We further used single nucleotide polymorphism (SNP) markers to quantify relatedness and levels of genetic variation. We found that, across species, current populations grew faster and advanced their flowering. These shifts were correlated with changes in aridity at the population origins, suggesting that increased drought induced evolution of earlier flowering, whereas decreased drought lead to weak or inverse shifts in flowering phenology. In five out of the 13 species, however, the SNP markers detected strong differences in genetic variation and relatedness between the past and current populations collected, indicating that other evolutionary processes may have contributed to changes in phenotypes. Our results suggest that changes in aridity may have influenced the evolutionary trajectories of many plant species in different regions of Europe, and that flowering phenology may be one of the key traits that is rapidly evolving.
