Defensive coloration is not a reliable indicator of fungal infection in aposematic poison frogs

Title (eng)
Defensive coloration is not a reliable indicator of fungal infection in aposematic poison frogs
Author
Lia Schlippe Justicia
Author
Carolin Dittrich
Author
Ossi Nokelainen
Author
Bibiana Rojas
Abstract (eng)
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.
Keywords (eng)
AmazonCarotenoidsChytrid FungusDendrobates TinctoriusMelaninPathogensPoison FrogVisual Signal
Type (eng)
journal article
Language
[eng]
Persistent identifier
https://phaidra.vetmeduni.ac.at/o:5209
DOI
10.1093/beheco/araf137
Is in series
Title (eng)
Behavioral Ecology
Volume
37
Issue
1
ISSN
1045-2249
Issued
2026
Number of pages
11
Publication
Oxford University Press
Version type (eng)
version of record (published version)
Date issued
2026
Access rights (eng)
open access
License
CC BY 4.0 International
Rights statement (eng)
© The Author(s) 2025