TITLE:
Bufotes and Pelophylax as Models for Semi-Arid Terrestrial and Aquatic Life: A Hypothesis-Generating Comparative Review of Ecological, Physiological and Candidate-Gene Evidence
AUTHORS:
Gad Degani, Dani Bercovich
KEYWORDS:
Bufotes sitibundus, Pelophylax bedriagae, Amphibians, Arid Adaptation, Aquatic Adaptation, Comparative Genomics, Candidate Genes, Hypothesis-Generating Review, Levels of Evidence, Phylogeography, Aquaporins, Heat-Shock Proteins, Osmoregulation, Israel
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.16 No.4,
October
20,
2026
ABSTRACT: Amphibians are highly sensitive to environmental change because their life cycles, physiology, reproduction and survival depend strongly on water availability. The genera Bufotes and Pelophylax represent contrasting ecological strategies among anurans. The green toad Bufotes sitibundus is widely distributed across Mediterranean, semi-arid and arid regions and can persist in dry terrestrial habitats, whereas the Levant water frog Pelophylax bedriagae is closely associated with permanent freshwater habitats. This article is explicitly a hypothesis-generating comparative review rather than a report of demonstrated genomic adaptation. It separates three classes of evidence throughout: 1) demonstrated observations obtained directly from the two focal Israeli species, chiefly ecological, distributional and physiological data, including published measurements of oxygen consumption and carbon dioxide production under thermal and dehydration stress; 2) inference from related Eurasian taxa such as Bufotes viridis, B. variabilis, Pelophylax ridibundus, P. lessonae and P. kurtmuelleri; and 3) general amphibian or vertebrate background knowledge. Candidate genes associated with water balance, osmoregulation, heat and oxidative stress, hypoxia, immunity, skin-barrier function, metabolism and endocrine regulation are therefore presented as explicit, testable predictions and not as established species-specific differences, because no direct expression, sequence or functional data are yet available for either focal species. Because Bufotes and Pelophylax are distantly related genera, ecological contrast between them cannot by itself distinguish convergent or lineage-specific genomic adaptation from inherited phylogenetic difference. Current evidence supports marked ecological and physiological differentiation between the two genera, but direct whole-genome comparisons of B. sitibundus and P. bedriagae remain unavailable. Comparative genome sequencing, population-genomic analyses and functional studies are therefore required to test the proposed candidate pathways and to identify lineage-specific mechanisms of adaptation.