Uncertainty in predicting range dynamics of endemic alpine plants under climate warming.

Correlative species distribution models have long been the predominant approach to predict species' range responses to climate change. Recently, the use of dynamic models is increasingly advocated for because these models better represent the main processes involved in range shifts and also simulate transient dynamics. A well-known problem with the application of these models is the lack of data for estimating necessary parameters of demographic and dispersal processes. However, what has been hardly considered so far is the fact that simulating transient dynamics potentially implies additional uncertainty arising from our ignorance of short-term climate variability in future climatic trends. Here, we use endemic mountain plants of Austria as a case study to assess how the integration of decadal variability in future climate affects outcomes of dynamic range models as compared to projected long-term trends and uncertainty in demographic and dispersal parameters. We do so by contrasting simulations of a so-called hybrid model run under fluctuating climatic conditions with those based on a linear interpolation of climatic conditions between current values and those predicted for the end of the 21st century. We find that accounting for short-term climate variability modifies model results nearly as differences in projected long-term trends and much more than uncertainty in demographic/dispersal parameters. In particular, range loss and extinction rates are much higher when simulations are run under fluctuating conditions. These results highlight the importance of considering the appropriate temporal resolution when parameterizing and applying range-dynamic models, and hybrid models in particular. In case of our endemic mountain plants, we hypothesize that smoothed linear time series deliver more reliable results because these long-lived species are primarily responsive to long-term climate averages.

Do metal concentrations in moss from the Zackenberg area, Northeast Greenland, provide a baseline for monitoring?

PURPOSE: This study aims at evaluating (a) whether concentrations of a suite of elements in mosses sampled in the arctic region around Zackenberg reflect background concentrations useful for estimating pollution levels in industrialized parts of the northern hemisphere as is attempted, e.g. in the framework of the UNECE ICP Vegetation monitoring programme, and (b) whether there are any influences from Zackenberg research station detectable in these concentrations. METHODS: Two moss species were sampled according to guidelines used in the UNECE ICP Vegetation programme. Samples were analysed for ¹95Pt at low resolution, ²7Al, 5²Cr, 65Cu, 66Zn, 95Mo, ¹¹¹Cd, ¹¹8Sn, ¹²¹Sb and ²°8Pb at medium resolution and 75As at high resolution on an Element 2 inductively coupled plasma sector field mass spectrometer. RESULTS: Except for Al, As and Cr, data from Zackenberg showed significantly lower mean element concentrations than those reported in comparable studies from all over the world including those from other Arctic environments. Minimum concentrations in Zackenberg mosses were consistently below all values reported so far for all elements analysed. The results of a PCA suggested only a slight impact from Zackenberg research station on concentrations of Cd, Mo and Zn in moss. CONCLUSIONS: We conclude that the sites in Zackenberg can be considered true background sites providing baseline concentrations of at least eight elements for comparable monitoring studies.

Bayesian hypothesis testing supports long-distance Pleistocene migrations in a European high mountain plant (Androsace vitaliana, Primulaceae).

Colonization of the south-western European mountain ranges is suggested to have predominantly progressed from the Iberian Peninsula eastwards, but this hypothesis has never been tested in a statistical framework. Here, we test this hypothesis using Androsace vitaliana, a high elevation species with eight mostly allopatric subspecies, which is widely but disjunctly distributed across all major south-western European mountain ranges. To this end, we use plastid and nuclear sequence data as well as fingerprint (amplified fragment length polymorphisms) data and employ Bayesian methods, which allow co-estimation of genealogy and divergence times using explicit demographic models, as well as hypothesis testing via Bayes factors. Irrespective of the ambiguity concerning where A. vitaliana started to diversify -- both the Alps and the mountain ranges of the Iberian Peninsula outside the Pyrenees were possible -- colonization routes were not simply unidirectional, but involved Pleistocene connections between the Alps and mountain ranges of the Iberian Peninsula bypassing the interjacent Pyrenees via long-distance dispersal. In contrast, the species' post-glacial history is shaped by regional gene pool homogenization resulting in the genetic pattern showing good congruence with geographical proximity in agreement with a vicariance model, but only partly supporting current taxonomy.