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Walderich LM, Susanto AW, Svensson M, Fohrman A, Wirén M, O'Dwyer R, Försäter K, Rödin-Mörch P, Höglund J
iScience 29 (4) 115395 [2026-04-17; online 2026-03-17]
The European green toad (Bufotes viridis) is Sweden's most threatened amphibian. Its range has contracted over the past century, with many local extinctions; remaining populations are fragmented and often isolated. Since the 1990s, conservation has focused on translocations to existing breeding sites and new localities, but many efforts have had limited success. We detected lower genetic diversity in Scandinavian populations (southern Sweden and nearby Denmark) than in Poland, plus strong structure and differentiation among Scandinavian subpopulations, implying unexpectedly low gene flow despite translocations. Small, isolated populations are strongly affected by drift, and whole-genome analyses reveal inbreeding and high genetic load in some subpopulations. We recommend reassessing source populations for translocations: the stock used in captive breeding and most past releases shows intermediate diversity but also signs of divergent selection and putative local adaptation. Management should balance minimizing inbreeding depression against risks of outbreeding depression and erosion of local adaptation risks.
NGI Stockholm (Genomics Production) [Service]
National Genomics Infrastructure [Service]
PubMed 42006334
DOI 10.1016/j.isci.2026.115395
Crossref 10.1016/j.isci.2026.115395
pmc: PMC13084336
pii: S2589-0042(26)00770-4