Ciencia habilitada por datos de especímenes

Louw, G. J., L. J. Potgieter, and D. M. Richardson. 2024. Myoporum (Scrophulariaceae): Introduction, naturalization, and invasion of an enigmatic tree genus in South Africa. South African Journal of Botany 168: 529–541. https://doi.org/10.1016/j.sajb.2024.03.022

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.

Minghetti, E., P. M. Dellapé, M. Maestro, and S. I. Montemayor. 2024. Evaluating the climatic suitability of Engytatus passionarius Minghetti et al. (Heteroptera, Miridae) as a biological control agent of the invasive stinking passion flower Passiflora foetida L. in Australia through ecological niche models. Biological Control 191: 105461. https://doi.org/10.1016/j.biocontrol.2024.105461

Passiflora foetida is a climbing vine, native to the Neotropical Region that is causing major economic and ecological damage in Australia, where it is rapidly spreading. Traditional control options, such as cutting, manual uprooting, and herbicide applications are only effective for local management. Currently, the plant bug Engytatus passionarius is the most promising biological control agent. Specificity tests performed in its native range in Argentina suggest it is highly specific to the plant, and it has not been observed in the field associated with other plants. As climate determines the establishment of insects, knowing if the environmental conditions suit their requirements is key to introducing a species in a region. Also, an overlap between the climatic niches of species is an indicator of similar requirements. To explore the possibilities of a successful establishment of E. passionarius in Australia, ecological niche models (ENM) were built for the plant bug and for the vine and their overlap was measured. The ENM projected to Australia recognized suitable environmental conditions for the establishment of E. passionarius in several regions where P. foetida is present, both for current and future scenarios. Moreover, the niche of the plant bug is almost completely overlapped with that of the vine. All the aforementioned evidence seems to indicate that E. passionarius has a good chance to become an effective biological control agent of P. foetida.

ter Huurne, M. B., L. J. Potgieter, C. Botella, and D. M. Richardson. 2023. Melaleuca (Myrtaceae): Biogeography of an important genus of trees and shrubs in a changing world. South African Journal of Botany 162: 230–244. https://doi.org/10.1016/j.sajb.2023.08.052

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.

Cousins-Westerberg, R., N. Dakin, L. Schat, G. Kadereit, and A. M. Humphreys. 2023. Evolution of cold tolerance in the highly stress-tolerant samphires and relatives (Salicornieae: Amaranthaceae). Botanical Journal of the Linnean Society. https://doi.org/10.1093/botlinnean/boad009

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.

Richard-Bollans, A., C. Aitken, A. Antonelli, C. Bitencourt, D. Goyder, E. Lucas, I. Ondo, et al. 2023. Machine learning enhances prediction of plants as potential sources of antimalarials. Frontiers in Plant Science 14. https://doi.org/10.3389/fpls.2023.1173328

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.

Clemente, K. J. E., and M. S. Thomsen. 2023. High temperature frequently increases facilitation between aquatic foundation species: a global meta‐analysis of interaction experiments between angiosperms, seaweeds, and bivalves. Journal of Ecology. https://doi.org/10.1111/1365-2745.14101

Many studies have quantified ecological impacts of individual foundation species (FS). However, emerging data suggest that FS often co‐occur, potentially inhibiting or facilitating one another, thereby causing indirect, cascading effects on surrounding communities. Furthermore, global warming is accelerating, but little is known about how interactions between co‐occurring FS vary with temperature.Shallow aquatic sedimentary systems are often dominated by three types of FS: slower‐growing clonal angiosperms, faster‐growing solitary seaweeds, and shell‐forming filter‐ and deposit‐feeding bivalves. Here, we tested the impacts of one FS on another by analyzing manipulative interaction experiments from 148 papers with a global meta‐analysis.We calculated 1,942 (non‐independent) Hedges’ g effect sizes, from 11,652 extracted values over performance responses, such as abundances, growths or survival of FS, and their associated standard deviations and replication levels. Standard aggregation procedures generated 511 independent Hedges’ g that was classified into six types of reciprocal impacts between FS.We found that (i) seaweeds had consistent negative impacts on angiosperms across performance responses, organismal sizes, experimental approaches, and ecosystem types; (ii) angiosperms and bivalves generally had positive impacts on each other (e.g., positive effects of angiosperms on bivalves were consistent across organismal sizes and experimental approaches, but angiosperm effect on bivalve growth and bivalve effect on angiosperm abundance were not significant); (iii) bivalves positively affected seaweeds (particularly on growth responses); (iv) there were generally no net effects of seaweeds on bivalves (except for positive effect on growth) or angiosperms on seaweeds (except for positive effect on ‘other processes’); and (v) bivalve interactions with other FS were typically more positive at higher temperatures, but angiosperm‐seaweed interactions were not moderated by temperature.Synthesis: Despite variations in experimental and spatiotemporal conditions, the stronger positive interactions at higher temperatures suggest that facilitation, particularly involving bivalves, may become more important in a future warmer world. Importantly, addressing research gaps, such as the scarcity of FS interaction experiments from tropical and freshwater systems and for less studied species, as well as testing for density‐dependent effects, could better inform aquatic ecosystem conservation and restoration efforts and broaden our knowledge of FS interactions in the Anthropocene.

Reichgelt, T., A. Baumgartner, R. Feng, and D. A. Willard. 2023. Poleward amplification, seasonal rainfall and forest heterogeneity in the Miocene of the eastern USA. Global and Planetary Change 222: 104073. https://doi.org/10.1016/j.gloplacha.2023.104073

Paleoclimate reconstructions can provide a window into the environmental conditions in Earth history when atmospheric carbon dioxide concentrations were higher than today. In the eastern USA, paleoclimate reconstructions are sparse, because terrestrial sedimentary deposits are rare. Despite this, the eastern USA has the largest population and population density in North America, and understanding the effects of current and future climate change is of vital importance. Here, we provide terrestrial paleoclimate reconstructions of the eastern USA from Miocene fossil floras. Additionally, we compare proxy paleoclimate reconstructions from the warmest period in the Miocene, the Miocene Climatic Optimum (MCO), to those of an MCO Earth System Model. Reconstructed Miocene temperatures and precipitation north of 35°N are higher than modern. In contrast, south of 35°N, temperatures and precipitation are similar to today, suggesting a poleward amplification effect in eastern North America. Reconstructed Miocene rainfall seasonality was predominantly higher than modern, regardless of latitude, indicating greater variability in intra-annual moisture transport. Reconstructed climates are almost uniformly in the temperate seasonal forest biome, but heterogeneity of specific forest types is evident. Reconstructed Miocene terrestrial temperatures from the eastern USA are lower than modeled temperatures and coeval Atlantic sea surface temperatures. However, reconstructed rainfall is consistent with modeled rainfall. Our results show that during the Miocene, climate was most different from modern in the northeastern states, and may suggest a drastic reduction in the meridional temperature gradient along the North American east coast compared to today.

Bywater‐Reyes, S., R. M. Diehl, A. C. Wilcox, J. C. Stella, and L. Kui. 2022. A Green New Balance: Interactions among riparian vegetation plant traits and morphodynamics in alluvial rivers. Earth Surface Processes and Landforms 47: 2410–2436. https://doi.org/10.1002/esp.5385

The strength of interactions between plants and river processes is mediated by plant traits and fluvial conditions, including above‐ground biomass, stem density and flexibility, channel and bed material properties, and flow and sediment regimes. In many rivers, concurrent changes in 1) the composition of riparian vegetation communities as a result of exotic species invasion and 2) shifts in hydrology have altered physical and ecological conditions in a manner that has been mediated by feedbacks between vegetation and morphodynamic processes. We review how Tamarix, which has invaded many U.S. Southwest waterways, and Populus species, woody pioneer trees that are native to the region, differentially affect hydraulics, sediment transport, and river morphology. We draw on flume, field, and modeling approaches spanning the individual seedling to river‐corridor scales. In a flume study, we found differences in the crown morphology, stem density, and flexibility of Tamarix compared to Populus influenced near‐bed flow velocities in a manner that favored aggradation associated with Tamarix. Similarly, at the patch and corridor scales, observations confirmed increased aggradation with increased vegetation density. Furthermore, long‐term channel adjustments were different for Tamarix‐ versus Populus‐dominated reaches, with faster and greater geomorphic adjustments for Tamarix. Collectively, our studies show how plant‐trait differences between Tamarix and Populus, from individual seedlings to larger spatial and temporal scales, influence the co‐adjustment of rivers and riparian plant communities. These findings provide a basis for predicting changes in alluvial riverine systems which we conceptualize as a Green New Balance model that considers how channels may adjust to changes in plant traits and community structure in additional to alterations in flow and sediment supply. We offer suggestions regarding how the Green New Balance can be used in management and invasive species management.

Sluiter, I. R. K., G. R. Holdgate, T. Reichgelt, D. R. Greenwood, A. P. Kershaw, and N. L. Schultz. 2022. A new perspective on Late Eocene and Oligocene vegetation and paleoclimates of South-eastern Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 596: 110985. https://doi.org/10.1016/j.palaeo.2022.110985

We present a composite terrestrial pollen record of latest Eocene through Oligocene (35.5–23 Ma) vegetation and climate change from the Gippsland Basin of south-eastern Australia. Climates were overwhelmingly mesothermic through this time period, with mean annual temperature (MAT) varying between 13 and 18 °C, with an average of 16 °C. We provide evidence to support a cooling trend through the Eocene–Oligocene Transition (EOT), but also identify three subsequent warming cycles through the Oligocene, leading to more seasonal climates at the termination of the Epoch. One of the warming episodes in the Early Oligocene appears to have also occurred at two other southern hemisphere sites at the Drake Passage as well as off eastern Tasmania, based on recent research. Similarities with sea surface temperature records from modern high southern latitudes which also record similar cycles of warming and cooling, are presented and discussed. Annual precipitation varied between 1200 and 1700 mm/yr, with an average of 1470 mm/yr through the sequence. Notwithstanding the extinction of Nothofagus sg. Brassospora from Australia and some now microthermic humid restricted Podocarpaceae conifer taxa, the rainforest vegetation of lowland south-eastern Australia is reconstructed to have been similar to present day Australian Evergreen Notophyll Vine Forests existing under the sub-tropical Köppen-Geiger climate class Cfa (humid subtropical) for most of the sequence. Short periods of cooler climates, such as occurred through the EOT when MAT was ~ 13 °C, may have supported vegetation similar to modern day Evergreen Microphyll Fern Forest. Of potentially greater significance, however, was a warm period in the Early to early Late Oligocene (32–26 Ma) when MAT was 17–18 °C, accompanied by small but important increases in Araucariaceae pollen. At this time, Araucarian Notophyll/Microphyll Vine Forest likely occurred regionally.

Vasconcelos, T., J. D. Boyko, and J. M. Beaulieu. 2021. Linking mode of seed dispersal and climatic niche evolution in flowering plants. Journal of Biogeography. https://doi.org/10.1111/jbi.14292

Aim: Due to the sessile nature of flowering plants, movements to new geographical areas occur mainly during seed dispersal. Frugivores tend to be efficient dispersers because animals move within the boundaries of their preferable niches, so seeds are more likely to be transported to environments tha…