Biology subjects

Jones, N. T.

Publications and source records attributed to Jones, N. T..

4 recordsLinked to original sources

bioRxiv2022

Phenotypic and transcriptional response of Daphnia pulicaria to the combined effects of temperature and predation

Daphnia, an ecologically important zooplankton species in lakes, shows both genetic adaptation and phenotypic plasticity in response to temperature and fish predation, but little is known about the molecular basis of these responses and their potential interactions. We performed a factorial experiment exposing laboratory-propagated Daphnia pulicaria clones from two lakes in the Sierra Nevada mountains of California to normal or high temperature (15{degrees}C or 25{degrees}C) in the presence or absence of fish kairomones, then measured changes in life history and gene expression. Exposure to kairomones increased upper thermal tolerance limits for physiological activity in both clones. Cloned individuals matured at a younger age in response to higher temperature and kairomones, while size at maturity, fecundity and population intrinsic growth were only affected by temperature. At the molecular level, both clones expressed more genes differently in response to temperature than predation, but specific genes involved in metabolic, cellular, and genetic processes responded differently between the two clones. Although gene expression differed more between clones from different lakes than experimental treatments, similar phenotypic responses to predation risk and warming arose from these clone-specific patterns. Our results suggest that phenotypic plasticity responses to temperature and kairomones interact synergistically, with exposure to fish predators increasing the tolerance of Daphnia pulicaria to stressful temperatures, and that similar phenotypic responses to temperature and predator cues can be produced by divergent patterns of gene regulation.

ecology↗

bioRxiv2020

Chronic Corticosterone Pretreatment Reverses Psilocybin Effects on Mouse Anxious and Hedonic Behaviors

Despite observed correlations between acute glucocorticoid release, self-reported anxiety, and long-term treatment outcomes for human studies using psilocybin-assisted psychotherapy approaches, the mechanistic relationship between psychedelic-dependent stress and subsequent behavioral responses remains unclear. Using rodents, direct manipulation of stress-associated hormone responses can be achieved with established pharmacologic models for the assessment of antidepressant and anxiolytic therapeutics. Here, chronic oral corticosterone-induced suppression of the hypothalamic-pituitary-adrenal axis is used to assess the relevance of drug-induced glucocorticoid release on the acute, post-acute, and long-term effects of psilocybin in male C57BL/6J mice. In these studies, psilocybin-induced acute anxiogenesis was found to be correlated to post-acute anxiolysis in a dose-dependent manner. Psilocybin also displayed acute increases in plasma corticosterone, but a post-acute anxiolytic effect in the novelty suppressed feeding test. Both effects were lost when psilocybin was administered in animals pre-exposed to chronic oral corticosterone. A similar long-term interaction between chronic corticosterone and psilocybin administration was observed in an open field test occurring one week after drug administration. Psilocybin administration alone led to more time spent in the center of the arena, but animals spent less time in the center with chronic corticosterone exposure. Intriguingly, these interactive effects were absent in animals exposed to brief isoflurane anesthesia after drug treatment. Overall, these experiments identify acute glucocorticoid release as a relevant biological modifier for the post-acute and long-term behavioral effects of psilocybin in mice. Rodent studies are thus suggested as a tractable means to address neuroendocrine mechanisms supporting context-dependent psychedelic effects in mammalian species.

animal behavior and cognition↗

bioRxiv2018

Cryptic Dispersal Networks Connect Habitat Patches in ways not Captured by Distance

Species interact with the physical world in complex ways, and life history strategies might cause species to differ in how they experience connectedness of the same landscape. As a consequence, dispersal limitation might be present but not captured by distance-based measures of connectivity. To test these ideas, we surveyed plant communities that associate with serpentine soils but differ in dispersal mode (gravity, animal, or wind), and used satellite imagery to quantify forms of landscape connectivity associated with each dispersal mode. Our data yielded two key insights: First, dispersal limitation appeared to be absent using a conventional distance-based measure of connectivity, but emerged after considering forms of landscape connectivity relevant to each dispersal mode. Second, the landscape variables that emerged as important to each dispersal mode were generally consistent with our predictions based on putative dispersal vectors, and included interactive effects that allude to the altered efficacy of animal dispersal in invaded landscapes. Our results have broad implications for understanding how ecological communities reorganize as landscapes are fragmented, patches are lost, and the function of dispersal life histories is altered.

ecology↗

bioRxiv2017

Frequency-dependent Maternal Effects across Species and Environments

O_LIMaternal provisioning of offspring in response to environmental conditions (\"maternal environmental effects\") has been argued as the missing link in plant life histories. Although empirical evidence suggests that maternal responses to abiotic conditions are common, there is little understanding of the prevalence of maternal provisioning in competitive environments.\nC_LIO_LIWe tested how competition in two soil moisture environments affects maternal provisioning of offspring seed mass. Specifically, we varied conspecific frequency from 90% (intraspecific competition) to 10% (interspecific competition) for 15 pairs of annual plant species that occur in California.\nC_LIO_LIWe found that conspecific frequency affected maternal provisioning (seed mass) in 48% of species, and that these responses included both increased (20%) and decreased (24%) seed mass. In contrast, 68% of species responded to competition through changes in per capita fecundity (seed number), which generally decreased as conspecific frequency increased. The direction and magnitude of frequency-dependent seed mass depended on the identity of the competitor, even among species in which fecundity was not affected by competitor identity.\nC_LIO_LISynthesis. Our research demonstrates how species responses to different competitive environments manifest through maternal provisioning, and that these responses alter previous estimates of environmental maternal effects and reproductive output; future study is needed to understand their combined effects on population and community dynamics.\nC_LI

ecology↗