Our September Issue is now available online! Featuring methods for 3D phenotyping, identification of ghost parasitoids, estimating the area of applicability of spatial prediction models & much more!

Read on to discover our featured articles, specially selected by Executive Editor Rob Freckleton, plus find out more about the Applications and Practical Tools articles we have in this issue.

Featured Articles

Identification of ghost parasitoids Incidence of parasitism is often underestimated because ‘ghost’ parasitoids (dead unemerged parasitoids or those that have emerged leaving the host carcasses) are difficult to detect and identify. This study by Paula & Andow demonstrates that the use of melting curve analysis (MCA) of host carcasses can detect and identify DNA of ghost parasitoids even a month after host death.

Broad-scale Applications of the Raspberry Pi *open access* The field of biology has seen tremendous technological progress in recent years, fuelled by the exponential growth in processing power and high-level computing, and the rise of global information sharing. Low-cost single-board computers are predicted to be one of the key technological advancements to further revolutionise this field. In this article, Jolle W. Jolles focuses on the most widely used single-board computer, the Raspberry Pi, in a review its broad applications and uses across the biological domain.

Marine artificial light at night *open access* The increasing illumination of our world by artificial light at night (ALAN) has created a new field of research with impacts now being demonstrated across taxa, biological ranks and spatial scales. Following advances in terrestrial ecology, marine ALAN has become a rapidly growing research area, but technological limitations, complexities of researching many coastal and marine ecosystems and the interdisciplinary nature of ALAN research present numerous challenges. Here, Tidau et al. share practical advice and solutions that have proven useful for marine ALAN research.

EasyDCP *open access* High-throughput 3D phenotyping is a rapidly emerging field that has widespread application for measurement of individual plants. Despite this, high-throughput plant phenotyping is rarely used in ecological studies due to financial and logistical limitations. In this article, Feldman et al. introduce EasyDCP, a Python package for 3D phenotyping, which uses photogrammetry to automatically reconstruct 3D point clouds of individuals within populations of container plants and output phenotypic trait data.

Predicting into unknown space *open access* Machine learning algorithms have become very popular for spatial mapping of the environment due to their ability to fit nonlinear and complex relationships. However, this ability comes with the disadvantage that they can only be applied to new data if these are similar to the training data. Since spatial mapping requires predictions to new geographic space which in many cases goes along with new predictor properties, a method to assess the area to which a prediction model can be reliably applied is required. Here, Meyer & Pebesma suggest a new method for estimating the area of applicability of spatial prediction models.


ENMeval 2.0 *free access* Quantitative evaluations to optimise complexity have become standard for avoiding overfitting of ecological niche models (ENMs) that estimate species’ potential geographic distributions. ENMeval was the first R package to make such evaluations widely accessible for the Maxent algorithm. It also provided multiple methods for partitioning occurrence data and reported various performance metrics. Requests by users, recent developments in the field, and needs for software compatibility, Kass et al. have undertaken a major redesign and expansion, as well as conducting a literature review to investigate trends in ENMeval use.

Practical Tools

WildWID *free access* Radio-frequency identification (RFID) tags represent some of the smallest animal-borne technologies available and are frequently used for understanding fine-scale associations between animals and their environments. However, currently available devices are often prohibitively expensive or difficult to customise. In answer to this, Rafiq et al. present WildWID, an open-source radio-frequency identification system that can be used for detecting encounters between tags and loggers or integrated into more advanced experimental set-ups for triggering audio or visual playbacks following the detection of RFID tag codes. WildWID systems can be made using commercially available components (costing ~$20 USD for tags and ~$60 for loggers) and can be customised to fit project and species-specific needs.

Assaying lepidopteran flight directionality *free access* Research into lepidopteran flight behaviour using techniques such as disappearance bearing observations and flight simulator trials provide important information on how organisms orient using environmental cues. These techniques possess limitations, however, which preclude their use for rare or threatened species. Here, Parlin et al. develop a new non-invasive tethering technique for lepidopterans, demonstrate this method using eight different species and include a video tutorial. The catch-tether-release method has significant implications for movement research with lepidopteran species of variable conservation status or that are considered pests.

The Whales on the Cover

This issue’s cover image shows three sperm whales (Physeter macrocephalus) beginning to dive in calm waters off the Galápagos Islands. As they descend, these whales will make Morse-code-like patterns of clicks, called codas, that convey their cultural identity. In their article, Hersh et al. present a new method that uses contaminated mixture models and hierarchical clustering to detect potential biological structure in acoustic datasets, such as sperm whale coda datasets. By looking for redundant, stereotyped, and distinct ‘identity calls’, the method was able to detect sperm whale cultures, wren subspecies, and cricket species. For taxa that readily vocalise but are cryptic or difficult to access, this method could help quantify behavioral diversity and population structure.