James Drummond

Global warming is one of the biggest threats to global biodiversity causing not only changes in the patterns of precipitation and temperature but also disturbing ecological interactions. The aim of our study was to forecast the effect of climate change on the distribution of food‐deceptive orchid species whose pollination strategy relies on a strict association with pollinators and co‐occurring rewarding Faboideae plants. We used the ecological niche modeling approach to evaluate future overlap of the suitable niches of studied orchid species with the predicted distribution of their ecological partners. Models were made based on two different global circulation models (FIO, CNRM). CNRM projections predict expansion of orchids' geographical range. In contrast, FIO prediction is less optimistic, forecasting species range contraction. The studied Faboideae species showed different responses to predicted global warming with no consistent patterns in how their suitable niches might change. Most climate change projections and scenarios of the future modifications of temperature and precipitation patterns do not predict significant loss of suitable niches of Trichocolletes bees (Colletidae) pollinating Diuris species. However, global warming has the potential to disrupt interactions between the studied orchids and their co‐occurring pea plants by altering the overlap of their geographical ranges which can further disturb pollination success. CNRM projections predict an overall loss of Faboideae within the potential geographical range of Diuris brumalis. Conversely, FIO projections suggest a less extensive predicted divergence. Our simulations offer suggestions for conservation strategies of orchids and potentially for other species that have a similar pollination strategy. The areas indicated here as suitable in the future for the occurrence of all ecological partners can be important climate refugia to consider in local conservation plans. The approach used in our study can serve as a model for understanding the potential effects of climate change on the strength of the pollination system via food deception.

Centella asiatica is a medicinal plant recognized for its various benefits contributed by its metabolites and has been used as a food supplement since prehistorical times across various cultures. Due to the reliance on natural populations of C. asiatica and the impacts of environmental factors on its yield and centelloside production, there is a need to identify suitable cultivation areas for this species. We employed ecological niche modelling with bioclimatic and soil variables to evaluate the suitability of cultivation under current and future climatic scenarios. Our results identified suitable areas for cultivating C. asiatica worldwide, indicating its potential for global commercial cultivation. However, the niche reconstruction of highly concentrated centelloside was restricted to South and Southeast Asia due to the lack of available data. When we projected the modelled niche of centelloside in these regions, we observed a lower occurrence probability in some areas, suggesting potential challenges in cost-effectiveness. Nevertheless, our results suggest a consistent future distribution for this species when we projected the modelled niche under future climates based on various socio-economic scenarios. This study not only identifies suitable areas to develop commercial cultivation for C. asiatica with highly concentrated centelloside, but also provides supporting evidence of the consistency of these areas, which can increase its sustainability.

Understanding belowground plant-microbial interactions is fundamental to predicting how plant species respond to climate change, particularly in global drylands. However, these interactions are poorly understood, especially for keystone grass species like the pan-palaeotropical Themeda triandra. Here, we used 16S rRNA amplicon sequencing to characterise microbiota in rhizospheres and bulk soils associated with T. triandra. We applied this method to eight native sites across a 3-fold aridity gradient (aridity index range = 0.318 to 0.903 = 87 % global aridity distribution) in southern Australia. By examining the relative contributions of climatic, edaphic, ecological, and host specific phenotypic traits, we identified the ecological drivers of core T. triandra-associated microbiota. We show that aridity had the strongest effect on shaping these core microbiotas, and report that a greater proportion of bacterial taxa that were from the core rhizosphere microbiomes were also differentially abundant in more arid T. triandra regions. These results suggest that T. triandra naturally growing in soils under more arid conditions have greater reliance on rhizosphere core taxa than plants growing under wetter conditions. Our study underscores the likely importance of targeted recruitment of bacteria into the rhizosphere by grassland keystone species, such as T. triandra, when growing in arid conditions. This bacterial soil recruitment is expected to become even more important under climate change.

Parasitic weeds in the genera Orobanche, Phelipanche (broomrapes) and Striga (witchweeds) have a devastating impact on food security across much of Africa, Asia and the Mediterranean Basin. Yet, how climatic factors might affect the range expansion of these weeds in the context of global environmental change remains unexplored. We examined satellite‐based environmental variables such as surface temperature, root zone soil moisture, and elevation, in relation to parasitic weed distribution and environmental conditions over time, in combination with observational data from the Global Biodiversity Information Facility (GBIF). Our analysis reveals contrasting environmental and altitude preferences in the genera Striga and Orobanche. Asiatic witchweed (Striga asiatica), which infests corn, rice, sorghum, and sugar cane crops, appears to be expanding its range in high elevation habitats. It also shows a significant association with heat‐moisture coupling events, the frequency of which is rising in such environments. These results point to geographical shifts in distribution and abundance in parasitic weeds due to climate change.

Myoporum is a genus of trees and shrubs native to the Northern Hemisphere that has been introduced to many parts of the world, mainly for ornamental purposes. We assessed the introduction history, distribution, and extent of naturalization/invasion for Myoporum species in South Africa.Information was collated to determine key events associated with the introduction, establishment, and naturalization of Myoporum in South Africa. Data were collated to determine the current distribution of the genus in South Africa. Twenty sites in the Western Cape were sampled to determine correlates of naturalization. Myoporum was first recorded in South Africa in 1934. Three species were confirmed to be present in South Africa: M. insulare, M. laetum and M. montanum (37 %, 25 % and 24 % of all iNaturalist records respectively). Most records are from the Western Cape (91 %) and small parts of the Eastern Cape; isolated populations occur in Gauteng and the Northern Cape. We could not confirm the presence M. petiolatum, M. tenuifolium or M. tetrandrum. Field surveys revealed widespread naturalization of M. insulare (46 % of all Research Grade observations in iNaturalist); this species was categorized code D1 in the introduction-naturalization-invasion continuum. Myoporum laetum (C3) and M. montanum (C2) are also widely naturalized but over smaller areas. Naturalized populations comprised predominantly juvenile M. insulare plants occurring in highly disturbed (transformed) habitats. Formal risk analyses for all Myoporum species in South Africa are needed as the basis for re-evaluation of their status in national legislation.

The genus Carpobrotus N.E.Br. comprises between 12 and 25 species, most of which are native to South Africa. Some Carpobrotus species are considered among the most damaging invasive species in coastal dune systems worldwide. In their introduced areas, these species represent a serious threat to native species and significantly impact soil conditions and geochemical processes. Despite being well studied, the taxonomy of Carpobrotus remains problematic, as the genus comprises a complex of species that hybridize easily and are difficult to distinguish from each other. To explore the population genetic structure of invasive Carpobrotus species (i.e., C. acinaciformis and C. edulis) across a significant part of their native and non-native ranges, we sampled 40 populations across Argentina, Italy, New Zealand, Portugal, South Africa, Spain, and the USA. We developed taxon-specific microsatellite markers using a Next Generation Sequencing approach to analyze the population genetic structure and incidence of hybridization in native and non-native regions. We identified three genetically distinct clusters, which are present in both the native and non-native regions. Based on a set of selected morphological characteristics, we found no clear features to identify taxa morphologically. Our results suggest that the most probable sources of global introductions of Carpobrotus species are the Western Cape region of South Africa and the coastline of California. We suggest that management actions targeting Carpobrotus invasions globally should focus on preventing additional introductions from the east coast of South Africa, and on searching for prospective biocontrol agents in the Western Cape region of South Africa.

The number of naturalised and invasive woody plant species has increased rapidly in recent decades. Despite the increasing interest in tree and shrub invasions, little is known about the invasion ecology of most species. This paper explores the global movement of species in the genus Melaleuca (Myrtaceae; here including the genus Callistemon). We assess the global introduction history, distribution and biogeographic status of the genus. Various global species occurrence databases, citizen science (iNaturalist), and the literature were used.Seventy-two species [out of 386 Melaleuca species; 19%] have been introduced to at least 125 regions outside their native range. The main regions of global Melaleuca introductions are Southeast Asia, the southern parts of North America, south-eastern South America, southern Africa and Europe. The earliest record of a Melaleuca species outside of the native range of the genus is 1789. First records of Melaleuca species outside their native range were most commonly recorded in the 1960s, with records from all over the world. The main reasons for Melaleuca introductions were for use in the tea tree (pharmaceutical value) and ornamental horticulture industries. Melaleuca introductions, naturalizations and invasions are recent compared to many other woody plant taxa. Experiences in Florida and South Africa highlight the potential of Melaleuca species to spread rapidly and have significant ecological impacts. It is likely that the accumulating invasion debt will result in further naturalization and invasion of Melaleuca species in the future.

Predicting the likelihood that non-native species will be introduced into new areas remains one of conservation’s greatest challenges and, consequently, it is necessary to adopt adequate management measures to mitigate the effects of future biological invasions. At present, not much information is available on the areas in which non-native aquatic plant species could establish themselves in the Iberian Peninsula. Species distribution models were used to predict the potential invasion risk of (1) non-native aquatic plant species already established in the peninsula (32 species) and (2) those with the potential to invade the peninsula (40 species). The results revealed that the Iberian Peninsula contains a number of areas capable of hosting non-native aquatic plant species. Areas under anthropogenic pressure are at the greatest risk of invasion, and the variable most related to invasion risk is temperature. The results of this work were used to create the Invasion Risk Atlas for Alien Aquatic Plants in the Iberian Peninsula, a novel online resource that provides information about the potential distribution of non-native aquatic plant species. The atlas and this article are intended to serve as reference tools for the development of public policies, management regimes, and control strategies aimed at the prevention, mitigation, and eradication of non-native aquatic plant species.

Low temperature constitutes one of the main barriers to plant distributions, confining many clades to their ancestrally tropical biome. However, recent evidence suggests that transitions from tropical to temperate biomes may be more frequent than previously thought. Here, we study the evolution of cold and frost tolerance in the globally distributed and highly stress-tolerant Salicornieae (Salicornioideae, Amaranthaceae s.l.). We first generate a phylogenetic tree comprising almost all known species (85-90%), using newly generated (n = 106) and published nuclear-ribosomal and plastid sequences. Next, we use geographical occurrence data to document in which clades and geographical regions cold-tolerant species occur and reconstruct how cold tolerance evolved. Finally, we test for correlated evolution between frost tolerance and the annual life form. We find that frost tolerance has evolved independently in up to four Northern Hemisphere lineages but that annuals are no more likely to evolve frost tolerance than perennials, indicating the presence of different strategies for adapting to cold environments. Our findings add to mounting evidence for multiple independent out-of-the-tropics transitions among close relatives of flowering plants and raise new questions about the ecological and physiological mechanism(s) of adaptation to low temperatures in Salicornieae.

Plants are a rich source of bioactive compounds and a number of plant-derived antiplasmodial compounds have been developed into pharmaceutical drugs for the prevention and treatment of malaria, a major public health challenge. However, identifying plants with antiplasmodial potential can be time-consuming and costly. One approach for selecting plants to investigate is based on ethnobotanical knowledge which, though having provided some major successes, is restricted to a relatively small group of plant species. Machine learning, incorporating ethnobotanical and plant trait data, provides a promising approach to improve the identification of antiplasmodial plants and accelerate the search for new plant-derived antiplasmodial compounds. In this paper we present a novel dataset on antiplasmodial activity for three flowering plant families – Apocynaceae, Loganiaceae and Rubiaceae (together comprising c. 21,100 species) – and demonstrate the ability of machine learning algorithms to predict the antiplasmodial potential of plant species. We evaluate the predictive capability of a variety of algorithms – Support Vector Machines, Logistic Regression, Gradient Boosted Trees and Bayesian Neural Networks – and compare these to two ethnobotanical selection approaches – based on usage as an antimalarial and general usage as a medicine. We evaluate the approaches using the given data and when the given samples are reweighted to correct for sampling biases. In both evaluation settings each of the machine learning models have a higher precision than the ethnobotanical approaches. In the bias-corrected scenario, the Support Vector classifier performs best – attaining a mean precision of 0.67 compared to the best performing ethnobotanical approach with a mean precision of 0.46. We also use the bias correction method and the Support Vector classifier to estimate the potential of plants to provide novel antiplasmodial compounds. We estimate that 7677 species in Apocynaceae, Loganiaceae and Rubiaceae warrant further investigation and that at least 1300 active antiplasmodial species are highly unlikely to be investigated by conventional approaches. While traditional and Indigenous knowledge remains vital to our understanding of people-plant relationships and an invaluable source of information, these results indicate a vast and relatively untapped source in the search for new plant-derived antiplasmodial compounds.