Climate Change Dependence in Ex Situ Conservation of Wild Medicinal Plants in Crete, Greece.

Over 80% of the global population addresses their primary healthcare needs using traditional medicine based on medicinal plants. Consequently, there's a rising demand for these plants for both household and industrial use at local, regional, national, and international levels. However, wild harvesting has negatively impacted natural ecosystems. Cultivating medicinal species has been proposed as a conservation strategy to alleviate this pressure. Yet, in this age of global climate change concerns, smallholder farmers' views on the benefits of such cultivation clash with the uncertainties of climate change impacts, amplifying their anxieties. In this context, the climate change dependence of ex situ cultivation of ten wild medicinal taxa with significant ethnopharmacological interest in Crete, Greece, were studied, projecting their potential habitat suitability under various future climate scenarios. The results demonstrated species-specific effects. Based on the potential cultivation area gains and losses, these effects can be categorized into three groups. We also outlined the spatial patterns of these gains and losses, offering valuable insights for regional management strategies benefiting individual practitioners.

Local Insect Availability Partly Explains Geographical Differences in Floral Visitor Assemblages of Arum maculatum L. (Araceae).

Geographical variation in abundance and composition of pollinator assemblages may result in variable selection pressures among plant populations and drive plant diversification. However, there is limited knowledge on whether differences in local visitor and pollinator assemblages are the result of site-specific strategies of plants to interact with their pollinators and/or merely reflect the pollinator availability at a given locality. To address this question, we compared locally available insect communities obtained by light-trapping with assemblages of floral visitors in populations of Arum maculatum (Araceae) from north vs. south of the Alps. We further investigated whether and how the abundance of different visitors affects plants' female reproductive success and examined the pollen loads of abundant visitors. Local insect availability explained inter-regional differences in total visitor abundance, but only partly the composition of visitor assemblages. Northern populations predominantly attracted females of Psychoda phalaenoides (Psychodidae, Diptera), reflecting the high availability of this moth fly in this region. More generalized visitor assemblages, including other psychodid and non-psychodid groups, were observed in the south, where the availability of P. phalaenoides/Psychodidae was limited. Fruit set was higher in the north than in the south but correlated positively in both regions with the abundance of total visitors and psychodids; in the north, however, this relationship disappeared when visitor abundances were too high. High pollen loads were recorded on both psychodids and other Diptera. We demonstrate for the first time that the quantitative assessment of floral visitor assemblages in relation to locally available insect communities is helpful to understand patterns of geographical variation in plant-pollinator interactions. This combined approach revealed that geographical differences in floral visitors of A. maculatum are only partly shaped by the local insect availability. Potential other factors that may contribute to the geographical pattern of visitor assemblages include the region-specific attractiveness of this plant species to flower visitors and the population-specific behavior of pollinators.

Antennae of psychodid and sphaerocerid flies respond to a high variety of floral scent compounds of deceptive Arum maculatum L.

Insect-pollinated plants often release complex mixtures of floral scents to attract their pollinators. Yet scent compounds eliciting physiological or behavioural responses in pollinators have only been identified in few plant species. The sapromyiophilous aroid Arum maculatum releases a highly diverse dung-like scent with overall more than 300 different compounds recorded so far to attract its psychodid and other fly pollinators. The volatiles' role in pollinator attraction is mostly unknown. To identify potential behaviourally active compounds, we recorded electroantennographic responses of four Psychodidae and one Sphaeroceridae species to (1) inflorescence scents of A. maculatum and (2) the scents released by cow dung, likely imitated by the plant species. Here we show that these flies are sensitive to 78 floral volatiles of various chemical classes, 18 of which were also found in cow dung. Our study, which for the first time determined physiologically active compounds in the antennae of Psychoda spp. and Sphaeroceridae, identified various volatiles not known to be biologically active in any floral visitors so far. The obtained results help deciphering the chemical basis that enables A. maculatum and other plants, pollinated by psychodids and sphaerocerids, to attract and deceive their pollinators.

Variation in scent amount but not in composition correlates with pollinator visits within populations of deceptive Arum maculatum L. (Araceae).

Floral scent is vital for pollinator attraction and varies among and within plant species. However, little is known about how inter-individual variation in floral scent affects the abundance and composition of floral visitor assemblages within populations. Moreover, for deceptive plants it is predicted that intra-population variation in scent can be maintained by negative frequency-dependent selection, but empirical evidence is still lacking. To investigate the ecological and evolutionary relations between inter-individual scent variation (i.e., total emission and composition) and floral visitors in deceptive plants, we studied floral scent, visitor assemblages, and fruit set in two populations of fly-pollinated (Psychodidae, Sphaeroceridae; Diptera) and deceptive Arum maculatum from Austria (JOS) and northern Italy (DAO). By correlating individual data on floral scent and visitor assemblages, we show that inter-individual variation in floral scent partly explains variation in visitor assemblages. The quantity of floral scent emitted per individual correlated positively with visitor abundance in both populations but explained visitor composition only in DAO, where strongly scented inflorescences attracted more sphaerocerid flies. However, in each population, the composition of floral scent did not correlate with the composition of floral visitors. There was also no evidence of negative frequency-dependent selection on floral scent. Instead, in JOS, more frequent scent phenotypes attracted more pollinators and were more likely to set an infructescence than rarer ones. Our results show that floral scent, despite being key in pollinator attraction in A. maculatum, only partly explains variation in pollinator abundance and composition. Overall, this study is the first to shed light on the importance of inter-individual variation in floral scent in explaining floral visitor assemblages at the population level in a deceptive plant species.

Floral Scents of a Deceptive Plant Are Hyperdiverse and Under Population-Specific Phenotypic Selection.

Floral scent is a key mediator in plant-pollinator interactions. However, little is known to what extent intraspecific scent variation is shaped by phenotypic selection, with no information yet in deceptive plants. In this study, we collected inflorescence scent and fruit set of the deceptive moth fly-pollinated Arum maculatum L. (Araceae) from six populations north vs. five populations south of the Alps, accumulating to 233 samples in total, and tested for differences in scent, fruit set, and phenotypic selection on scent across this geographic barrier. We recorded 289 scent compounds, the highest number so far reported in a single plant species. Most of the compounds occurred both north and south of the Alps; however, plants of the different regions emitted different absolute and relative amounts of scent. Fruit set was higher north than south of the Alps, and some, but not all differences in scent could be explained by differential phenotypic selection in northern vs. southern populations. This study is the first to provide evidence that floral scents of a deceptive plant are under phenotypic selection and that phenotypic selection is involved in shaping geographic patterns of floral scent in such plants. The hyperdiverse scent of A. maculatum might result from the imitation of various brood substrates of its pollinators.

From wild harvest towards precision agriculture: Use of Ecological Niche Modelling to direct potential cultivation of wild medicinal plants in Crete.

Understanding the distribution of wild medicinal plants and areas that are suitable for cultivation of these plants is important for both conservation and agriculture. Here, we study ten taxa with known ethnopharmacological uses, which have been used extensively in traditional medicine and as culinary supplements. We aim to (1) predict and map the potential habitat suitability for these taxa across the study area, (2) investigate spatial patterns that could have management implications, such as niche similarities among the taxa and suitability "hotspots" with the use of novel indices, and (3) develop a platform where parts of this information can be accessed and utilized by all interested groups, from the policy-maker level to the individual practitioner level. Ecological Niche Models developed for each study taxon, based on topographic, bioclimatic, soil, and land use variables had high predictive power and were used as the basis for suitability visualization. A series of informative indices were also calculated and mapped, revealing spatial patterns not readily observable from the single-taxon predictions, and providing valuable information to managers. Finally, a web-based, easy-to-use application was also created, where the predicted suitability scores for the study area can be made accessible to anyone interested. The application can provide information both in a visual form (i.e. maps of predicted suitability) and in a numerical form (i.e. estimated suitability scores for all taxa in a given geographical location). This study provides the scientific tools to make a step towards cultivating a group of economically important wild medicinal plants in Crete, as well as the tools to disseminate this information to decision makers and practitioners, and eventually integrate the research findings in local agricultural practices.

Exogenous induction of thermogenesis in Arum concinnatum by salicylic acid.

Arum concinnatum Schott is a highly thermogenic species, with the temperature of the appendix exceeding ~10.9°C above the ambient temperature during thermogenesis, whereas the rates of respiration of the male florets in intact inflorescences peak at 0.92µmol s-1 g-1, which is the highest rate so far measured among the plants. Here, we attempt the ex situ exogenous induction of thermogenesis in whole inflorescences and in separate appendices of the spadix, and explore the thermogenic patterns under controlled laboratory conditions of light and temperature. Mature but unopened inflorescences and appendices showed thermogenic responses when treated with salicylic acid (SA), but not when treated with distilled water (control). With regard to light conditions, the responses revealed only one significant difference for inflorescences, which concerns the higher maximum temperature in the continuous light treatment compared with continuous dark. Along the ambient temperature gradient, at the lowest temperature edge individuals remained stable close to ambient temperature and to control. These findings suggest that, in general, ex situ exogenous induction of thermogenesis can be achieved in whole inflorescences and in separate appendices of spadix of A. concinnatum using SA. This study also indicates that SA acts independently of light conditions, while exogenous induction of thermogenesis takes place within an ambient temperature range.