Body size mediates latitudinal population differences in the response to chytrid fungus infection in two amphibians

• Published in: Oecologia Vol. 204; no. 1; pp. 71 - 81
• Main Authors: Meurling, Sara, Siljestam, Mattias, Cortazar-Chinarro, Maria, Åhlen, David, Rödin-Mörch, Patrik, Ågren, Erik, Höglund, Jacob, Laurila, Anssi
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2024; Springer; Springer Nature B.V
• Subjects: Amphibians; Aquatic reptiles; Batrachochytrium; Batrachochytrium dendrobatidis; Biologi; Biological Sciences; Biomedical and Life Sciences; Body size; Bufo bufo; Ecology; Ecology (including Biodiversity Conservation); Ekologi; Fungi; Geographical variation; Health aspects; hosts; Hydrology/Water Resources; Infection; Infections; intraspecific variation; Latitude; Lethal effects; Life Sciences; Loads (forces); Mortality; Natural Sciences; Naturvetenskap; Original Research; Pathogens; Plant Sciences; Population decline; provenance; Rana arvalis; Reptiles & amphibians; Sublethal effects; Survival; Toads; Tolerance; Tolerance; Sublethal effects; Body size; Geographical variation; Batrachochytrium dendrobatidis
• ISSN: 0029-8549; 1432-1939; 1432-1939
• DOI: 10.1007/s00442-023-05489-5

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis ( Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different Bd GPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis . Bd -mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo . Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.