Ecology of Mediterranean lichens and plants: application of species distribution models.

Many studies include Species Distribution Modelling (SDM) techniques to define spatial biogeographic patterns of species and to explore ecological variability. As first, a study on the ecology of infrageneric taxa of genus Solenopsora is presented. The genus includes 25 species of foliose, rupicolous lichens, mostly occurring in temperate and subtropical regions. In Europe, only some taxa range from central Europe (with continental/Atlantic climate) to the Mediterranean, while others are restricted to Mediterranean area. The aim was to explore ecological variability of infrageneric taxa (with diverse distributions), for understanding whether the responses to environmental factors are species-specific. SDMs is used to predict taxa distributions using future climatic scenarios, which take in account climate change effects. It is a fact that climate trends nowadays are anomalous if compared with previous climatic oscillations of the Earth. Climate change already generated distributional range shifts for several species, and increased risk of extinction, or of invasion, disrupting ecosystem dynamics and services. Policy and decision-making can be supported by SDMs, thus improving the effectiveness of global change mitigation strategies. Since conservation efforts can be expensive, and time consuming, SDMs provide a way for optimizing and better addressing resources. The second section host a study on current and future (2070) distribution models of some Sardinian orchids. The Mediterranean is one of the most important biodiversity hot-spots in the world, labelled also as a climate change hot-spot. Plants distribution in the Mediterranean area was strongly influenced by its ecological complexity. In this area, climate changes could heavily impact communities, and the most relevant effect could be an increased occurrence of taxa adapted to dry and hot conditions, leading extinction of endemic taxa. In Europe, Sardinia is one of orchids major biodiversity hotspot (60 taxa). Sardinian ecosystems are changing in consequence of climate change, and while some species are reducing their habitat, others are widening their distribution. Future climate change scenarios for Sardinia depict a situation in which the average monthly temperatures increase, and precipitations increase by 20–50% in the cold season, and decrease of 20–50% in the rest of the year. The third study is on SDMs used for investigating taxonomic questions. The case of Pterygiopsis affinis, a rare crustose cyanolichen, adapted to the Mediterranean climate, is investigated. P. affinis is known to reproduce by apothecia. But, a sorediate morphotype was discovered in S Italy: its identity was never deeply investigated before. SDMs, together with morphological analysis, are used here to understand if this morphotype is an ecological variation of the species, or a new taxonomic entity. Most primitive lichens had a crustose, unorganized thallus, without an actual stratification, with blue algae as photobiont. These primitive lichens, still occurring in many environments, are normally crustose pioneer cyanolichens. They have an extreme phenotypic plasticity, ranging from “typical” to very uncommon forms, such as chimeras. This variability can also affect the reproductive strategies: some lichens can switch to asexual reproductive strategies, if driven by a limited availability of free-living algae. Taxonomy of lichens is traditionally based on anatomy and morphology of the fruiting bodies. Taxa which reproduce by vegetative structures only are normally treated separately from sexually reproducing ones. But, according to the hypothesis of species pairs, the same taxon can adopt different reproductive strategies in different ecological conditions. For all these reasons, the collocation of some taxa of cyanolichens is difficult, and species distribution modelling can be helpful in depicting the niche, and supporting taxonomical delimitation in complex situations.