Predator- and competitor-induced responses in amphibian populations that evolved different levels of pesticide tolerance.

Exposure to agrochemicals can drive rapid phenotypic and genetic changes in exposed populations. For instance, amphibian populations living far from agriculture (a proxy for agrochemical exposure) exhibit low pesticide tolerance, but they can be induced to possess high tolerance following a sublethal pesticide exposure. In contrast, amphibian populations close to agriculture exhibit high, constitutive tolerance to pesticides.

Local adaptation of the MHC class IIβ gene in populations of wood frogs (Lithobates sylvaticus) correlates with proximity to agriculture.

Major histocompatibility complex (MHC) genes code for membrane-embedded proteins that are involved in parasite/pathogen recognition. The link between the MHC and immunity makes these genes important genetic markers to evaluate in systems where infectious disease is associated with population declines. As human impacts on wildlife populations continue to increase, it is also essential to evaluate the role of MHC and immunity in the context of anthropogenic change.

Evolved pesticide tolerance influences susceptibility to parasites in amphibians.

Because ecosystems throughout the globe are contaminated with pesticides, there is a need to understand how natural populations cope with pesticides and the implications for ecological interactions. From an evolutionary perspective, there is evidence that pesticide tolerance can be achieved via two mechanisms: selection for constitutive tolerance over multiple generations or by inducing tolerance within a single generation via phenotypic plasticity. While both mechanisms can allow organisms to persist in contaminated environments, they might result in different performance trade-offs including population susceptibility to parasites.

Effect of Simultaneous Amphibian Exposure to Pesticides and an Emerging Fungal Pathogen, Batrachochytrium dendrobatidis.

Amphibian declines have been linked to numerous factors, including pesticide use and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Moreover, research has suggested a link between amphibian sensitivity to Bd and pesticide exposure. We simultaneously exposed postmetamorphic American toads (Anaxyrus americanus), western toads (A.

Sex-specific nutrient use and preferential allocation of resources to a sexually selected trait in Hyalella amphipods.

Although sexually dimorphic traits are often well studied, we know little about sex-specific resource use strategies that should underlie such dimorphism. We measured sex-specific responses in acquisition and assimilation of two fundamental resources, carbon (C) and phosphorus (P) in juvenile and mature Hyalella amphipods given low and high supplies of inorganic phosphate, analogous to oligotrophic and eutrophic conditions, respectively. Additionally, we quantified allocation of resources to sexual traits in males.