Avoidance behavior of Hyalella azteca in response to three common-use insecticides.

Non-target organisms in aquatic environments may experience lethal or sublethal effects following exposure to contaminants. Most protocols and regulations, however, are designed to provide protection from lethal effects and are thus based on conventional estimates of population lethality. The relative lack of reliable behavioral endpoints makes it challenging to implement regulations that are similarly protective against sublethal toxicity.

Eavesdropping Micropredators as Dynamic Limiters of Sexual Signal Elaboration and Intrasexual Competition.

AbstractTo thoroughly understand the drivers of dynamic signal elaboration requires assessing the direct and indirect effects of naturally interacting factors. Here, we use structural equation modeling to test multivariate data from in situ observations of sexual signal production against a model of causal processes hypothesized to drive signal elaboration. We assess direct and indirect effects, and relative impacts, of male-male competition and attacks by eavesdropping frog-biting midges (Diptera: Corethrellidae) on call elaboration of male túngara frogs ().

Integrating theoretical and empirical approaches for a robust understanding of endocrine flexibility.

There is growing interest in studying hormones beyond single 'snapshot' measurements, as recognition that individual variation in the endocrine response to environmental change may underlie many rapid, coordinated phenotypic changes. Repeated measures of hormone levels in individuals provide additional insight into individual variation in endocrine flexibility - that is, how individuals modulate hormone levels in response to the environment. The ability to quickly and appropriately modify phenotype is predicted to be favored by selection, especially in unpredictable environments.

Mathematical modeling reveals how the speed of endocrine regulation should affect baseline and stress-induced glucocorticoid levels.

Unpredictable environmental changes displace individuals from homeostasis and elicit a stress response. In vertebrates, the stress response is mediated mainly by glucocorticoids (GCs) which initiate physiological changes while minimizing allostatic overload. Individuals and species vary consistently in baseline and stress-induced GC levels and the speed with which GC levels can be upregulated or downregulated, but the extent to which variation in hormone regulation influences baseline and stress-induced GC levels is unclear.

Mixed Sex Effects on the Second-to-Fourth Digit Ratio of Túngara Frogs (Engystomops pustulosus) and Cane Toads (Rhinella marina).

Sexual dimorphism in the ratio of digit lengths has been correlated to behavioral, physiological, and morphological traits in a variety of taxa. While sexual dimorphism in the second-to-fourth digit length ratio (2D:4D) is a well-established indicator of prenatal androgen exposure in mammals, investigations into the patterns of 2D:4D and the drivers of such variation in other taxa are lacking. We used linear mixed effects models to gain a mechanistic understanding of the factors that drive variation in the scaling relationship between the lengths of the second and fourth digits in two species of anurans: túngara frogs (Engystomops pustulosus) and cane toads (Rhinella marina).

Size matters: insights from an allometric approach to evaluate control methods for invasive Australian Rhinella marina.

Invasive species are costly and difficult to control. In order to gain a mechanistic understanding of potential control measures, individual-based models uniquely parameterized to reflect the salient life-history characteristics of invasive species are useful. Using invasive Australian Rhinella marina as a case study, we constructed a cohort- and individual-based population simulation that incorporates growth and body size of terrestrial stages.