phaidra.vetmeduni.ac.at o:5209 DOI 10.1093/beheco/araf137 Defensive coloration is not a reliable indicator of fungal infection in aposematic poison frogs The expression of visual signals such as coloration can be altered by parasitic or pathogenic infections through multiple pathways, including resource reallocation, impaired tissue structure, and reduced pigment acquisition. These effects may compromise the functions of coloration and overall fitness. Conversely, the link between pigments and immunological defences can aid differently colored individuals in coping with infection. While the pigmentation-condition association has been widely studied in the context of sexual selection, far less is known about how pathogens affect defensive coloration, such as aposematic signals. Here, we investigated whether infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is reflected in characteristics of the melanin- and/or carotenoid-based coloration of the aposematic poison frog Dendrobates tinctorius in the wild. Using ddPCR to identify the frogs' infection status, and multispectral digital imaging to quantify their coloration traits, we show that neither type of coloration is a reliable indicator of Bd infection. Instead, body size influenced both infection outcomes and coloration, with sex-specific patterns suggesting potential ontogenetic or life-history trade-offs. Our findings highlight that the links between color expression and condition are more context- and taxa-dependent than often assumed, and suggest that, in D. tinctorius, defensive signals may remain stable despite pathogen exposure. eng Amazon Carotenoids Chytrid Fungus Dendrobates Tinctorius Melanin Pathogens Poison Frog Visual Signal 2026-06-23T10:12:35.263Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Schlippe Justicia;Lia; FN:Lia Schlippe Justicia X-ORCID:https://orcid.org/0000-0002-4362-2139 END:VCARD BEGIN:VCARD VERSION:3.0 N:Dittrich;Carolin; FN:Carolin Dittrich X-ORCID:https://orcid.org/0000-0002-4447-4481 END:VCARD BEGIN:VCARD VERSION:3.0 N:Nokelainen;Ossi; FN:Ossi Nokelainen X-ORCID:https://orcid.org/0000-0002-0278-6698 END:VCARD BEGIN:VCARD VERSION:3.0 N:Rojas;Bibiana; FN:Bibiana Rojas X-ORCID:https://orcid.org/0000-0002-6715-7294 END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 1408117 https://phaidra.vetmeduni.ac.at/o:5209 https://phaidra.vetmeduni.ac.at/api/object/o:5209/thumbnail LOMv1.0 discipline