The eastern boundary of the geographic range of the Pallas’ spadefoot Pelobates vespertinus (Anura, Amphibia) is limited by overwintering temperatures

Abstract

We studied the relationship between the geographic distribution of the Pallas’ spadefoot (Pelobates vespertinus) and the soil temperature regime at the eastern boundary of this species’ range (south-western West Siberia and northwest Kazakhstan). This species overwinters underground, burrowing down to 1.5 m or deeper and has poor frost tolerance – it is unable to withstand temperatures below 0 °C, therefore, the temperature at its overwintering depth has to be above zero. A cartographic approach to identifying the distribution of zero isotherms was used. Winter soil temperatures at depths of 80 cm, 120 cm, 160 cm and 240 cm were plotted, based on deep soil thermometer data and the outline of the spadefoot’s range was compared with close-to-zero isotherms in deep soil. Within the range of this species, the depth of the position of zero isotherms increases eastwards: from 80 cm in European Russia, to more than 160 cm in the south-west of Western Siberia. The eastern boundary of the species’ range lies in the forest-steppe, steppe and semi-desert zones in the Tobol-Ishim interfluve and further south, on the left bank area of the Turgai River. This boundary clearly coincides with the zero isotherm, which lies here at a depth of 160 cm, forming an impermeable barrier to the spadefoot’s distribution.

Piecing the barcoding puzzle of Palearctic water frogs (Pelophylax) sheds light on amphibian biogeography and global invasions

“…Most amphibians are sensitive to climate cooling (their range margins typically follow isotherms of overwintering temperatures, e.g., Bulakhova et al., 2020) and do not cross marine barriers unless under exceptional circumstances (e.g., Vences et al., 2003). Geological evidence for climatic oscillations, marine transgressions/regressions and tectonic events that presumably triggered land changes (insularity, landmass connections, orogenesis and desertification) thus offer great opportunities for BPT, in complement to the fossil record (Hipsley & Müller, 2014).…”

“…Most amphibians are sensitive to climate cooling (their range margins typically follow isotherms of overwintering temperatures, e.g., Bulakhova et al, 2020) and do not cross marine barriers unless under exceptional circumstances (e.g., Vences et al, 2003).…”

Occurrence of the amphibians in the Volga, Don River basins and adjacent territories (Russia): research in 1996-2020

“…The southern border of the distribution of many species ( Lissotriton vulgaris , Triturus cristatus , Bombina bombina , Bufo bufo , Rana arvalis , Rana temporaria ) coincides with the border of the middle and lower Volga ( Kuzmin 2012 Faizulin et al 2018 Zaks et al 2011 ). The range of Pelobates vespertinus almost completely coincides with the boundaries of the study area, with the exception of the Bryansk and Kaluga regions in the west and Ural Mountains in the east ( Bulakhova et al 2020 ). In a small part of the eastern area, Pelobates fuscus is included in boundaries of the study area ( Dufresnes et al 2019b ).…”

Metabolomic Profiling Reveals Differences in Hypoxia Response between Far Eastern and Siberian Frogs

“…The oxygen content in such places is high-ranging from 7 mg/L under the ice to 12-13 mg/L in shallow river sections without ice (our unpublished data). Laboratory experiments suggest that Far Eastern frogs are highly intolerant to hypoxia [16]. Conversely, the hypoxia-tolerant species R. amurensis mostly hibernates in stagnant water bodies, many of which experience severe winter freezing, with winter oxygen concentration dropping substantially below 1 mg/L (sometimes reaching anoxia).…”