Influence of environmental conditions on the distribution of Central Asian green toads with three ploidy levels
Abstract
We studied the distribution of Palearctic green toads (Bufo viridis subgroup), an anuran species group with three ploidy levels, inhabiting the Central Asian Amudarya River drainage. Various approaches (one-way, multivariate, components variance analyses and maximum entropy modelling) were used to estimate the effect of altitude, precipitation, temperature and land vegetation covers on the distribution of toads. It is usually assumed that polyploid species occur in regions with harsher climatic conditions (higher latitudes, elevations, etc.), but for the green toads complex, we revealed a more intricate situation. The diploid species (Bufo shaartusiensis and Bufo turanensis) inhabit the arid lowlands (from 44 to 789 m a.s.l.), while tetraploid Bufo pewzowi were recorded in mountainous regions (340–3492 m a.s.l.) with usually lower temperatures and higher precipitation rates than in the region inhabited by diploid species. The triploid species Bufo baturae was found in the Pamirs (Tajikistan) at the highest altitudes (2503–3859 m a.s.l.) under the harshest climatic conditions. Wir untersuchen die Verbreitung Paläarktischer Wechselkröten (Bufo viridis subgroup), einer Gruppe eng verwandter Anurenarten mit drei Ploidiestufen, in Zentralasien die Einzugsgebiet des Amu-Darja bewohnen. Unterschiedliche Methoden (uni- und multivariate und Komponentenvarianzanalyse, Maximum-Entropie-Model) wurden genutzt, um den Einfluss von Höhenlage, Niederschlag, Temperatur und Landbedeckung auf die Verbreitung der Kröten abzuschätzen. Es wird allgemein angenommen, dass polyploide Pflanzen- und Tierarten in Regionen mit harscheren Klimabedingungen vorkommen (höhere Breiten, grössere Höhenlagen, etc.). Die Situation ist bei Grünkröten jedoch komplizierter. Die diploiden Arten (Bufo shaartusiensis und B. turanensis) bewohnen die ariden Tieflandsgebiete (Höhen zwischen 44 und 789 m über dem Meeresspiegel), während die tetraploiden B. pewzowi in Gebirgsregionen gefunden wurden, die gewöhnlich niedrigere Temperaturen und höheren Niederschlag aufwiesen als die Verbreitungsgebiete der diploiden Formen. Triploide B. baturae wurden im Pamir (Tadschikistan) in den grössten Höhenlagen (2503–3859 m a.s.l.) und unter den extremsten Klimabedigungen angetroffen. Appendix S1. List of localities, ploidy levels (PL), geographic co-ordinates, altitudes, methods of ploidy determination (FC is flow DNA cytometry, and CH is chromosomes count), GenBank numbers, museum collection numbers and references. Table S1. Nuclear DNA content (pg) in various populations of diploid (Bufo shaartusiensis and B. turanensis), triploid (B. baturae), and tetraploid (B. pewzowi) species of green toads inhabiting the Amudarya River Drainage. Table S2. Environmental characters variation and reliability of differences between sample means (the Kolmogorov-Smirnov test; p > 0.05 is “–”; p < 0.05 is “+”; p < 0.01 is “++”; p < 0.001 is “+++”) for localities of toads (Bufo viridis subgroup) with various ploidy levels in the Amudarya River Drainage. Table S3. Results of the Kruskal-Wallis one-way analysis of variance (KWA) and weights of each variable in the first and second partial least squares regression (PLSR) components analysis. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.