4 (http://beast.bio.ed.ac.uk/Tracer). No well supported topological differences were found between the BI and ML trees; the ML tree was used in the subsequent analysis. Divergence in climate envelopes and allopatry Climate envelopes for western and eastern Amazonian Atelopus were modelled, subsequently mapped into geographic space and compared. selleck compound For our approach we used the presence data points listed in the Appendix (30 for all western and 54 for all eastern Amazonian Atelopus; Fig. 2). We created models based on seven macroscale bioclimatic parameters (Table 2) describing the availability of thermal energy and water, widely used in climate envelope models (e.g. Carnaval and
Moritz 2008; Rödder and Lötters 2009). Using DIVA-GIS 5.4 (Hijmans et al. 2001), bioclimatic parameters were extracted from the WorldClim
1.4 interpolation model with grid cell resolution 2.5 min for the period 1950–2000 (Hijmans et al. progestogen antagonist 2005) at (i) the species records as well as (ii) at 1,000 random points within both the MCP of the western and eastern Atelopus presence. For comparison, we computed boxplots with XLSTAT 2009 (Addinsoft). Subsequently, climate envelope models were generated and mapped with MaxEnt 3.2.19 (Phillips et al. 2006) based on the principle of maximum entropy (Jaynes 1957). This approach yields more reliable results than comparable methods (e.g. Elith et al. 2006; Heikkinen et al. 2006; Wisz et al. 2008), especially when data points for species number relatively few (e.g. Hernandez et al. 2006). Using default Histone demethylase settings, 25% of the data points were randomly reserved for model testing (duplicate presence records
in one grid cell were automatically removed). Prediction accuracy was evaluated through threshold-independent receiver operating characteristic (ROC) curves and the calculation of the area under the curve (AUC) method (e.g. Hanley and McNeil 1982). We acknowledge that there is currently some discussion about the suitability of AUC (Lobo et al. 2008). However, for our application AUC is the best possible choice. Elith and Graham (2009) pointed out that none of the frequently applied statistics in AUC are misleading and that appropriate statistics relevant to the application of the model need to be selected. The logistic MaxEnt output was chosen which is continuous and linear scaled (0–1, with 0.1 being the minimum Maxent value at the training records already suggesting suitability to the species under study; Phillips et al. 2006). Table 2 AUC values per model, climate envelope overlap in terms of I and D values and assessment of their similarity and equivalency via randomization tests (see text) Bioclimatic parameter Model fit D I AUCWestern, AUCEastern Overlap Identity Similarity Overlap Identity Similarity Western, Eastern Western, Eastern Annual mean temperature 0.798, 0.750 0.93 ns <0.01, <0.05 0.94 ns <0.01, <0.05 Mean monthly temperature range 0.796, 0.896 0.58 <0.01 <0.01, ns 0.72 <0.05 <0.