TY - JOUR

T1 - Toads phenotypically adjust their chemical defences to anthropogenic habitat change

AU - Bókony, Veronika

AU - Üveges, Bálint

AU - Verebélyi, Viktória

AU - Ujhegyi, Nikolett

AU - Móricz, Ágnes M

PY - 2019/2/28

Y1 - 2019/2/28

N2 - Despite the well-documented effects of human-induced environmental changes on the morphology, physiology, behaviour and life history of wild animals, next to nothing is known about how anthropogenic habitats influence anti-predatory chemical defence, a crucial fitness component of many species. We investigated the amount and composition of defensive toxins in adult common toads (Bufo bufo) captured in natural, agricultural and urban habitats, and in their offspring raised in a common-garden experiment. We found that, compared to toads captured from natural habitats, adults from both types of anthropogenic habitats had larger toxin glands (parotoids) and their toxin secretion contained higher concentrations of bufagenins, the more potent class of bufadienolide toxins. Furthermore, urban toads had lower concentrations of bufotoxins, the compounds with lower toxicity. None of these differences were present in the captive-raised juveniles; instead, toadlets originating from agricultural habitats had smaller parotoids and lower bufotoxin concentrations. These results suggest that toads' chemical defences respond to the challenges of anthropogenic environments via phenotypic plasticity. These responses may constitute non-adaptive consequences of pollution by endocrine-disrupting chemicals as well as adaptive adjustments to the altered predator assemblages of urban and agricultural habitats.

AB - Despite the well-documented effects of human-induced environmental changes on the morphology, physiology, behaviour and life history of wild animals, next to nothing is known about how anthropogenic habitats influence anti-predatory chemical defence, a crucial fitness component of many species. We investigated the amount and composition of defensive toxins in adult common toads (Bufo bufo) captured in natural, agricultural and urban habitats, and in their offspring raised in a common-garden experiment. We found that, compared to toads captured from natural habitats, adults from both types of anthropogenic habitats had larger toxin glands (parotoids) and their toxin secretion contained higher concentrations of bufagenins, the more potent class of bufadienolide toxins. Furthermore, urban toads had lower concentrations of bufotoxins, the compounds with lower toxicity. None of these differences were present in the captive-raised juveniles; instead, toadlets originating from agricultural habitats had smaller parotoids and lower bufotoxin concentrations. These results suggest that toads' chemical defences respond to the challenges of anthropogenic environments via phenotypic plasticity. These responses may constitute non-adaptive consequences of pollution by endocrine-disrupting chemicals as well as adaptive adjustments to the altered predator assemblages of urban and agricultural habitats.

KW - Agriculture

KW - Animals

KW - Bufanolides

KW - Bufo bufo/physiology

KW - Ecosystem

KW - Endocrine Disruptors

KW - Humans

KW - Larva/physiology

KW - Predatory Behavior/physiology

KW - Toxins, Biological/biosynthesis

U2 - 10.1038/s41598-019-39587-3

DO - 10.1038/s41598-019-39587-3

M3 - Article

C2 - 30816222

VL - 9

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

ER -