Leaf extracts from an exotic tree affect responses to chemical cues in the palmate newt, Lissotriton helveticus

Abstract

Chemical communication in aquatic species can affect many key life history traits, such as prey and predator detection and mate searching. However, changes in the environment can disrupt the effectiveness of signals and the ability of individuals to detect these signals. Many studies have examined the effect of secondary compounds from exotic plants on the ecology and physiology of a range of taxa, but whether the replacement of natural forests with exotic trees influences the behavioural responses of animals by disrupting chemical communication has rarely been investigated. We experimentally tested how eucalypt tree chemicals influenced three key aspects of chemical communication in adult male palmate newts. We tested for effects of both exposure to eucalypt water (i.e. extracts obtained by soaking leaves in mineral water) and the origin of newts (eucalypt plantations and natural oak forests). We examined whether exposure to eucalypt water altered the chemosensory ability of males to detect pools containing females or conspecific alarm cues and to find food. We found that eucalypt leachates had different effects on each behavioural trait. Fewer males detected female chemicals when exposed to the eucalypt than the oak water treatment, independent of the males' habitat of origin. Newts from oak forest were less able to detect conspecific alarm cues signalling predatory events when exposed to eucalypt water than when exposed to oak water, or than newts from eucalypt plantations for either water treatment. The ability of males to find food using chemical cues was similar in oak and eucalypt treatments. Our results suggest that chemical compounds not previously encountered during the evolutionary history of the species can influence the ability to respond to predators and locate mates. Future studies should explore the fitness costs associated with a reduced ability to respond to predators or detect mates.

Sex in the city: sexual selection and urban colonization in passerines

“…First, urban habitats could disrupt intraspecific communication of species that use coloration as a signal when competing for mates. Previous studies often show that signal transmission and reception is less efficient when animals are taken out of the environment in which they evolved [23,24]. If urban habitats disrupt visual signalling, we might expect links between the signal and male quality to be weakened leading females to mate with poor quality mates which could impact on the viability of future generations.…”

Eucalypt leaf litter impairs growth and development of amphibian larvae, inhibits their antipredator responses and alters their physiology

“…However, the indications of physiological stress were not severe, as eucalypt leaf litter had scarcely any effect on the immune status or oxidative stress of larvae. Therefore, we consider that eucalypt leachates were more likely interfering with predator recognition and not necessarily impairing their ability to respond, as was the case in other cases of non-native plant leachates ( Hickman and Watling, 2014 ; Iglesias-Carrasco et al , 2017b ), or more generally with other alterations of the ponds’ chemosphere ( Polo-Cavia et al , 2016 ).…”

“…Surprisingly, despite the large extent of eucalypt reforestations worldwide, the effects of eucalypt plantations on aquatic vertebrates (and particularly on amphibians) have received very little attention (but see Iglesias-Carrasco et al , 2016 and Iglesias-Carrasco et al , 2017a ). Although it has recently been shown that eucalypt leaf litter can impair mate and predator recognition in adult newts ( Iglesias-Carrasco et al , 2017b ), the extent to which it also affects growth, development or physiology of amphibian larvae is virtually unknown. To this end, we designed an experiment in which larvae of the European common frog ( Rana temporaria ) were exposed to either eucalypt or native oak leaf litter under laboratory conditions.…”

Invasive vegetation affects amphibian skin microbiota and body condition

“…For example, Fork et al (2015) found lower arthropod richness and lower abundance of some arthropod classes in Eucalyptus relative to oak woodland habitat-although an earlier study did not find differences in leaf litter arthropod richness in Eucalyptus vs. Quercus woodlands; Sax, 2002. In addition, Eucalyptus leaf extract has been found to compromise chemical communication in salamanders, and this could contribute to stress in Batrachoseps residing in invasive vegetation dominated habitat (Iglesias-Carrasco et al, 2017). Ultimately, a more comprehensive comparison of abiotic and biotic characteristics in relevant microhabitats is needed to fully understand the effects of invasive vegetation on terrestrial salamanders.…”