Biology subjects

Stevens, M.

Publications and source records attributed to Stevens, M..

3 recordsLinked to original sources

bioRxiv2018

The chemistry and pharmacology of putative synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS) 5F-PY-PICA, 5F-PY-PINACA, and their analogues

The structural diversity of synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS) has increased since the first examples were reported a decade ago. 5F-PY-PICA and 5F-PY-PINACA were identified in 2015 as putative SCRA NPS, although nothing is known of their pharmacology. 5F-PY-PICA, 5F-PY-PINACA, and analogues intended to explore structure-activity relationships within this class of SCRAs were synthesized and characterized by nuclear magnetic resonance spectroscopy and liquid chromatography-quadrupole time-of-flight-mass spectrometry. Using competitive binding experiments and fluorescence-based plate reader membrane potential assays, the affinities and activities of all analogues at cannabinoid type 1 and type 2 receptors (CB1 and CB2) were evaluated. All ligands showed minimal affinity for CB1 (pKi < 5), although several demonstrated moderate CB2 binding (pKi = 5.45-6.99). At 10 M none of the compounds produced an effect > 50% of CP55,950 at CB1, while several compounds showed a slightly higher relative efficacy at CB2. Unlike other SCRA NPS, 5F-PYPICA and 5F-PY-PINACA did not produce cannabimimetic effects in mice at doses up to 10 mg/kg.

pharmacology and toxicology↗

bioRxiv2018

Using camouflage for conservation: colour change in juvenile European lobster

Changes in coloration enable animals to refine their camouflage to match different visual environments. Such plasticity provides ecological benefits and could potentially be exploited to support conservation or stock enhancement efforts. One application could be ensuring that hatchery-reared animals, reared to stock wild populations, are appropriately matched to their environment on release. European lobster (Homarus gammarus) hatcheries aim to restock or enhance local lobster populations by rearing juveniles through their most vulnerable stages, then releasing them into the wild. However, little consideration has been given to their camouflage and the implications of matching individuals to their release site. This study assesses to what extent juvenile lobsters can change coloration to match their background and whether hatchery practices could be altered to enhance lobster camouflage. We test this by switching individuals between black or white backgrounds in the laboratory and monitoring their coloration over time. Our work demonstrates the capacity of juvenile lobsters to change lightness in response to their surroundings. We show that juvenile lobsters are capable of small changes in luminance (perceived lightness) to better match their background over 2-3 weeks. These changes potentially correspond to improved camouflage, based on a model of predator (European pollack, Pollachius pollachius) vision. However, over a longer period (5 weeks), lobsters maintained on either background converged on the same darker coloration, suggesting that lobsters also experience changes in appearance associated with ontogeny. By refining the approaches used here, there is potential for hatcheries to rear lobsters on backgrounds that better match their release site. However, such manipulations should be considered in the context of ontogenetic changes and release timing (which varies between stocking programmes). This study highlights the potential to use colour change in stocking and aquaculture, as well as gaps that could be addressed through further research in this area.

ecology↗

bioRxiv2018

Evolution of correlated complexity in the radically different courtship signals of birds-of-paradise

Ornaments used in courtship often vary wildly among species, reflecting the evolutionary interplay between mate preference functions and the constraints imposed by natural selection. Consequently, understanding the evolutionary dynamics responsible for ornament diversification has been a longstanding challenge in evolutionary biology. However, comparing radically different ornaments across species, as well as different classes of ornaments within species, is a profound challenge to understanding diversification of sexual signals. Using novel methods and a unique natural history dataset, we explore evolutionary patterns of ornament evolution in a group - the birds-of-paradise - exhibiting dramatic phenotypic diversification widely assumed to be driven by sexual selection. Rather than the tradeoff between ornament types originally envisioned by Darwin and Wallace, we found positive correlations among cross-modal (visual/acoustic) signals indicating functional integration of ornamental traits into a composite unit - the courtship phenotype. Furthermore, given the broad theoretical and empirical support for the idea that systemic robustness - functional overlap and interdependency - promotes evolutionary innovation, we posit that birds-of-paradise have radiated extensively through ornamental phenotype space as a consequence of the robustness in the courtship phenotype that we document at a phylogenetic scale. We suggest that the degree of robustness in courtship phenotypes among taxa can provide new insights into the relative influence of sexual and natural selection on phenotypic radiations.\n\nAuthor SummaryAnimals frequently vary widely in ornamentation, even among closely related species. Understanding the patterns that underlie this variation is a significant challenge, requiring comparisons among drastically different traits - like comparing apples to oranges. Here, we use novel analytical approaches to quantify variation in ornamental diversity and richness across the wildly divergent birds-of-paradise, a textbook example of how sexual selection can profoundly shape organismal phenotypes. We find that color and acoustic complexity, along with behavior and acoustic complexity, are positively correlated across evolutionary time-scales. Positive covariation among ornament classes suggests that selection is acting on correlated suites of traits - a composite courtship phenotype - and that this integration may be partially responsible for the extreme variation we see in birds-of-paradise.

evolutionary biology↗