Monitoring internet trade to inform species conservation actions

Specimens, parts and products of threatened species are now commonly traded on the internet. This could threaten the survival of some wild populations if inadequately regulated. We outline two methods to monitor internet sales of threatened species in order to assess potential threats and inform conservation actions. Our first method combines systematic monitoring of online offers of plants for sale over the internet with consultation by experts experienced in identifying plants collected from the wild based on images of the specimens, species identity and details of the trade. Our second method utilises a computational model, trained using Bayesian techniques to records that have been classified by an expert as wild collected or artificially propagated, to predict unknown properties of the traded taxa, such as whether a species being sold is collected from the wild or the identity of an unknown wild collected species. We used these methods to monitor internet trade in five genera of succulent plant species endemic to Madagascar, for which some have recently been listed for trade regulation under the Convention on International Trade in Endangered Species (CITES). This revealed potential threats to wild populations: for instance, almost all species recorded were of high conservation concern yet most offers for live plants were of apparently wild collected specimens (85%). Moreover, no records of international trade in the official CITES database were from the countries featured in our survey. Our model predicted with 89% accuracy whether the live plants were classified as propagated or wild collected by an expert, although accuracy dropped for data collected in the following summer due to a change in the patterns of sales. Our results highlight potential threats by internet trade to the survival of some CITES and non-CITES listed plant species from Madagascar. These should be addressed by further conservation actions and policy. More generally, our results reveal how standardised internet surveys can provide information on levels of trade in wild collected threatened species that could impact on natural populations and can provide data that can be incorporated into models to facilitate future monitoring and enforcement

Biomechanical, biochemical, and morphological mechanisms of heat shock-mediated germination in Carica papaya seed.

Carica papaya (papaya) seed germinate readily fresh from the fruit, but desiccation induces a dormant state. Dormancy can be released by exposure of the hydrated seed to a pulse of elevated temperature, typical of that encountered in its tropical habitat. Carica papaya is one of only a few species known to germinate in response to heat shock (HS) and we know little of the mechanisms that control germination in tropical ecosystems. Here we investigate the mechanisms that mediate HS-induced stimulation of germination in pre-dried and re-imbibed papaya seed. Exogenous gibberellic acid (GA3 ≥250 µM) overcame the requirement for HS to initiate germination. However, HS did not sensitise seeds to GA3, indicative that it may act independently of GA biosynthesis. Seed coat removal also overcame desiccation-imposed dormancy, indicative that resistance to radicle emergence is coat-imposed. Morphological and biomechanical studies identified that neither desiccation nor HS alter the physical structure or the mechanical strength of the seed coat. However, cycloheximide prevented both seed coat weakening and germination, implicating a requirement for de novo protein synthesis in both processes. The germination antagonist abscisic acid prevented radicle emergence but had no effect on papaya seed coat weakening. Desiccation therefore appears to reduce embryo growth potential, which is reversed by HS, without physically altering the mechanical properties of the seed coat. The ability to germinate in response to a HS may confer a competitive advantage to C. papaya, an opportunistic pioneer species, through detection of canopy removal in tropical forests

Effects of X-ray dose on rhizosphere studies using X-ray computed tomography

X-ray Computed Tomography (CT) is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such as root washing. However, one routinely unreported aspect of X-ray CT is the potential effect of X-ray dose on the soil-borne microorganisms and plants in rhizosphere investigations. Here we aimed to i) highlight the need for more consistent reporting of X-ray CT parameters for dose to sample, ii) to provide an overview of previously reported impacts of X-rays on soil microorganisms and plant roots and iii) present new data investigating the response of plant roots and microbial communities to X-ray exposure. Fewer than 5% of the 126 publications included in the literature review contained sufficient information to calculate dose and only 2.4% of the publications explicitly state an estimate of dose received by each sample. We conducted a study involving rice roots growing in soil, observing no significant difference between the numbers of root tips, root volume and total root length in scanned versus unscanned samples. In parallel, a soil microbe experiment scanning samples over a total of 24 weeks observed no significant difference between the scanned and unscanned microbial biomass values. We conclude from the literature review and our own experiments that X-ray CT does not impact plant growth or soil microbial populations when employing a low level of dose (<30 Gy). However, the call for higher throughput X-ray CT means that doses that biological samples receive are likely to increase and thus should be closely monitored

Investigating the microstructure of plant leaves in 3D with lab-based X-ray Computed Tomography

Background Leaf cellular architecture plays an important role in setting limits for carbon assimilation and, thus, photosynthetic performance. However, the low density, fine structure, and sensitivity to desiccation of plant tissue has presented challenges to its quantification. Classical methods of tissue fixation and embedding prior to 2D microscopy of sections is both laborious and susceptible to artefacts that can skew the values obtained. Here we report an image analysis pipeline that provides quantitative descriptors of plant leaf intercellular airspace using lab-based X-ray Computed Tomography (microCT). We demonstrate successful visualisation and quantification of differences in leaf intercellular airspace in 3D for a range of species (including both dicots and monocots) and provide a comparison with a standard 2D analysis of leaf sections. Results We used the microCT image pipeline to obtain estimates of leaf porosity and mesophyll exposed surface area (Smes) for three dicot species (Arabidopsis, tomato and pea) and three monocot grasses (barley, oat and rice). The imaging pipeline consisted of (1) a masking operation to remove the background airspace surrounding the leaf, (2) segmentation by an automated threshold in ImageJ and then (3) quantification of the extracted pores using the ImageJ ‘Analyze Particles’ tool. Arabidopsis had the highest porosity and lowest Smes for the dicot species whereas barley had the highest porosity and the highest Smes for the grass species. Comparison of porosity and Smes estimates from 3D microCT analysis and 2D analysis of sections indicates that both methods provide a comparable estimate of porosity but the 2D method may underestimate Smes by almost 50%. A deeper study of porosity revealed similarities and differences in the asymmetric distribution of airspace between the species analysed. Conclusions Our results demonstrate the utility of high resolution imaging of leaf intercellular airspace networks by lab-based microCT and provide quantitative data on descriptors of leaf cellular architecture. They indicate there is a range of porosity and Smes values in different species and that there is not a simple relationship between these parameters, suggesting the importance of cell size, shape and packing in the determination of cellular parameters proposed to influence leaf photosynthetic performance

Self-esteem influences the willingness to engage in COVID-19 prevention behavior and persuasion efficacy

Rationale: Behaviors such as hand-washing and vaccination save human lives during the COVID-19 pandemic and beyond. Yet, people differ widely in their willingness to engage in them. This investigation examines whether people's willingness to protect themselves physically from contracting coronavirus depends on their self-esteem. Based on self-verification theory, we propose that people who hold negative self-views are less motivated to protect their health which reduces their willingness to engage in recommended preventive measures such as mask-wearing and social-distancing.Objective: We set out to test (i) whether self-esteem predicts people's willingness to engage in COVID-19 pre-vention behaviors, (ii) whether this relationship is due to variance in motivation to protect one's health (as well as alternative mechanisms), and (iii) whether health messages can more successfully persuade low self-esteem people to follow preventive measures by framing those behaviors around protecting the health of others (vs. oneself).Methods: Four studies were conducted with U.S. and German residents. In Study 1, we examine the association between self-esteem, willingness to engage in self-protection behavior, health motivation, and several alternative accounts. In Study 2, we manipulate state self-esteem, and in Studies 3 and 4, we vary the target of COVID-19 prevention behaviors (self vs. other).Results: People with chronic or temporarily induced low self-esteem report a lower willingness to engage in COVID-19 prevention behaviors because they lack motivation to protect their health. Varying the protection target of preventive behaviors (self vs. others) interacts with self-esteem: Low self-esteem people are more willing to follow preventive measures (e.g., vaccination) when they are framed as protecting others (vs. oneself).Conclusions: Self-esteem impacts people's behavior during a global pandemic and needs to be considered when designing health communications. Public health messages can increase compliance among individuals with lower self-esteem by framing prevention behaviors as a way to protect the health of others