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Whole-cell voltage clamp recordings from $\textit{Drosophila melanogaster}$ photoreceptors have revolutionized the field of invertebrate visual transduction, enabling the use of $\textit{D. melanogaster}$ molecular genetics to study inositol-lipid signaling and Transient Receptor Potential (TRP) channels at the single-molecule level. A handful of labs have mastered this powerful technique, which enables the analysis of the physiological responses to light under highly controlled conditions. This technique allows control over the intracellular and extracellular media; the membrane voltage; and the fast application of pharmacological compounds, such as a variety of ionic or pH indicators, to the intra- and extracellular media. With an exceptionally high signal-to-noise ratio, this method enables the measurement of dark spontaneous and light-induced unitary currents ( i.e. spontaneous and quantum bumps) and macroscopic Light-induced Currents (LIC) from single $\textit{D. melanogaster}$ photoreceptors. This protocol outlines, in great detail, all the key steps necessary to perform this technique, which includes both electrophysiological and optical recordings. The fly retina dissection procedure for the attainment of intact and viable $\textit{ex vivo}$ isolated ommatidia in the bath chamber is described. The equipment needed to perform whole-cell and fluorescence imaging measurements are also detailed. Finally, the pitfalls in using this delicate preparation during extended experiments are explained.

Although the study of environmental change has long been of academic interest, the effects of change have become a much more pressing concern in the past few decades due to the often disruptive effect of human expansion and innovation. Researchers from many fields contribute to understanding our footprint on the natural world, problems we cause, and strategies we can employ to protect key species and ecosystems. Unfortunately, environmental change and its consequences are often studied without an awareness of the inherent attributes of the changes. As a result, the relevance of new advances in this field may be easily missed or misunderstood, and existing knowledge is not optimally applied. In this paper, we aim to facilitate the multi-disciplinary comparison of studies on environmental change, by offering a meta-level perspective on the process of change from the point of view of the individual animal. We propose an inclusive definition of change that can be applied across contexts, in which we take our understanding of. change. from an event to an interaction between a physical occurrence and an individual's state. Furthermore, we discuss key event- and individual-based attributes of change, their relevance in today's changing world, and how they relate to animals' available behavioural, physiological and cross-generational responses. We hope that by uncovering the underlying fundamental (or structure) of change, fellow scientists may better share their experience and knowledge gained from years of studying individual species and situations.

Sex ratio theory has been very successful in predicting under which circumstances parents should bias their investment towards a particular offspring sex. However, most examples of adaptive sex ratio bias come from species with well-defined mating systems and sex determining mechanisms, while in many other groups there is still an on-going debate about the adaptive nature of sex allocation. Here we study the sex allocation in the mealybug Planococcus citri, a species in which it is currently unclear how females adjust their sex ratio, even though experiments have shown support for facultative sex ratio adjustment. Previous work has shown that the sex ratio females produce changes over the oviposition period, with males being overproduced early and late in the laying sequence. Here we investigate this complex pattern further, examining both the robustness of the pattern and possible explanations for it. We first show that this sex allocation behaviour is indeed consistent across lines from three geographical regions. Second, we test whether females produce sons first in order to synchronize reproductive maturation of her offspring, although our data provide little evidence for this adaptive explanation. Finally we test the age at which females are able to mate successfully and show that females are able to mate and store sperm before adult eclosion. Whilst early-male production may still function in promoting protandry in mealybugs, we discuss whether mechanistic constraints limit how female allocate sex across their lifetime.

Predation has an important influence on life history traits in many organisms, especially when they are young. When cues of trout were present, juvenile sticklebacks grew faster. The increase in body size as a result of exposure to cues of predators was adaptive because larger individuals were more likely to survive predation. However, sticklebacks that had been exposed to cues of predators were smaller at adulthood. This result is consistent with some life history theory. However, these results prompt an alternative hypothesis, which is that the decreased size at adulthood reflects a deferred cost of early rapid growth. Compared to males, females were more likely to survive predation, but female size at adulthood was more affected by cues of predators than male size at adulthood, suggesting that size at adulthood might be more important to male fitness than to female fitness.