Journal of Experimental Biology - Latest Issue

• Precipitation patterns drive seasonal and spatial variation in behavior and physiology within an arid-adapted snake genus, Crotalus

  ABSTRACT

  Regardless of environmental conditions, organisms must maintain thermal and hydration states within tolerable limits, which can be especially challenging in arid environments. To mitigate environmental impacts, organisms may use behavioral and physiological alterations to buffer their internal states. Unfortunately, the degree to which behavioral and physiological responses contribute to tolerance of more arid conditions and the extent that organisms may tolerate increasing aridity remains unclear. Therefore, we simultaneously measured physiological and behavioral responses of Sonoran Desert rattlesnakes to seasonal and populational differences in aridity. We found that changes in evaporative water loss, osmolality and activity across seasons and between sites appear to be driven by precipitation patterns. Earlier, more frequent and greater amounts of rainfall between field sites resulted in differences in physiology and behavior within a single species. In contrast, two sympatric species showed similar seasonal physiological and behavioral patterns. Overall, our study demonstrates the importance of precipitation as a driver of activity and evaporative water loss and lends insight into the tolerance mechanisms that enable species to inhabit arid environments. Such information is critical as we attempt to predict impacts of climate change where most models forecast increased temperatures and decreased rainfall for many areas around the globe.

• ECR Spotlight – Derek Benson

  ABSTRACT

  ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Derek Benson is an author on ‘ Precipitation patterns drive seasonal and spatial variation in behavior and physiology within an arid-adapted snake genus, Crotalus’, published in JEB. Derek is a PhD Candidate in the lab of Dale DeNardo at Arizona State University, USA, investigating the mechanisms that enable organisms to tolerate adverse environmental conditions.

• Finding a path: local search behavior of Drosophila larvae

  ABSTRACT

  Orientation and navigation are essential features of animals living in changing environments. Typically, animals integrate a variety of allothetic and idiothetic cues to achieve their navigational goals. Allothetic cues, such as visual or chemical landmarks from the environment, provide an external frame of reference. In contrast, idiothetic cues are based on internal proprioceptive feedback and internal copies of motor commands.When Drosophila larvae are exposed briefly to a Teflon container holding a food stimulus, they show a characteristic behavior as soon as the container is removed: they briefly crawl away from the detected resource, remain in its vicinity and then return to the area where they experienced the earlier stimulus. We quantified this behavior with respect to the chemosensory nature of the stimulus, starvation time and genetic background of the larvae. We conclude that this behavior represents a centered local search. Furthermore, we exclude various external stimuli (vision and taste), which suggests that possibly idiothetic as opposed to allothetic cues have a stronger influence on the larval local search behavior. In the long term, this behavioral description will enable us to gain insights into the comparability of larval foraging strategies. We also want to investigate whether, despite the simpler organization of the larval brain and the alleged lack of a central complex, a brain region that is important for orientation and navigation in adult Drosophila and other insects, there are common solutions for the brain circuits underlying search behavior.

• A fish that escapes towards looming-disk stimuli

  ABSTRACT

  Escape responses are an essential part of the behavioural repertoires of almost all animals. In fish, it is thought that conserved circuits map retinal position to motor activity so that escapes are typically away from visual looming-disk stimuli. In support of this view, it has recently been demonstrated that this even causes reef fish to initially flee away from a secure shelter. Here, we provide a clear counterexample to the view that fish are generally bound to use similar and conserved circuitry. In shell-dwelling cichlids, visual looming-disk stimuli elicited but did not direct rapid escape C-starts. Rather, the initial direction of their C-starts was in the direction of their shell, even if this required the fish to start right towards the looming disk.

• Correction: Metabolic rate scaling, ventilation patterns and respiratory water loss in red wood ants: activity drives ventilation changes, metabolic rate drives water loss