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The influence of dispersal limitation on species ranges remains controversial. Considering the dramatic impacts of the last glaciation in Europe, species might not have tracked climate changes through time and, as a consequence, their present-day ranges might be in disequilibrium with current climate. For 1016 European plant species, we assessed the relative importance of current climate and limited postglacial migration in determining species ranges using regression modelling and explanatory variables representing climate, and a novel species-specific hind-casting-based measure of accessibility to postglacial colonization. Climate was important for all species, while postglacial colonization also constrained the ranges of more than 50 per cent of the species. On average, climate explained five times more variation in species ranges than accessibility, but accessibility was the strongest determinant for one-sixth of the species. Accessibility was particularly important for species with limited long-distance dispersal ability, with southern glacial ranges, seed plants compared with ferns, and small-range species in southern Europe. In addition, accessibility explained one-third of the variation in species' disequilibrium with climate as measured by the realized/potential range size ratio computed with niche modelling. In conclusion, we show that although climate is the dominant broad-scale determinant of European plant species ranges, constrained dispersal plays an important supplementary role.
Risk culture during the last 2000 years - from an aleatory society to the illusion of risk control
(2017)
The culture of risk is 2000 years old, although the term “risk” developed much later. The culture of merchants making decisions under uncertainty and taking the individual responsibility for the uncertain future started with the Roman “Aleatory Society”, continued with medieval sea merchants, who made business “ad risicum et fortunam”, and sustained to the culture of entrepreneurs in times of industrialisation and dynamic economic changes in the 18th and 19th century. For all long-term commercial relationships, the culture of honourable merchants with personal decision-making and individual responsibility worked well. The successful development of sciences, statistics and engineering within the last 100 years led to the conjecture that men can “construct” an economical system with a pre-defined “clockwork” behaviour. Since probability distributions could be calculated ex-post, an illusion to control risk ex-ante became a pattern in business and banking. Based on the recent experiences with the financial crisis, a “risk culture” should understand that human “Strength of Knowledge” is limited and the “unknown unknown” can materialise. As all decisions and all commercial agreements are made under uncertainty, the culture of honourable merchants is key to achieve trust in long-term economic relations with individual responsibility, flexibility to adapt and resilience against the unknown.