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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.
Campbell, L. C. E., E. T. Kiers, and G. Chomicki. 2022. The evolution of plant cultivation by ants. Trends in Plant Science. https://doi.org/10.1016/j.tplants.2022.09.005
Outside humans, true agriculture was previously thought to be restricted to social insects farming fungus. However, obligate farming of plants by ants was recently discovered in Fiji, prompting a re-examination of plant cultivation by ants. Here, we generate a database of plant cultivation by ants, identify three main types, and show that these interactions evolved primarily for shelter rather than food. We find that plant cultivation evolved at least 65 times independently for crops (~200 plant species), and 15 times in farmer lineages (~37 ant taxa) in the Neotropics and Asia/Australasia. Because of their high evolutionary replication, and variation in partner dependence, these systems are powerful models to unveil the steps in the evolution and ecology of insect agriculture.
Amaral, D. T., I. A. S. Bonatelli, M. Romeiro-Brito, E. M. Moraes, and F. F. Franco. 2022. Spatial patterns of evolutionary diversity in Cactaceae show low ecological representation within protected areas. Biological Conservation 273: 109677. https://doi.org/10.1016/j.biocon.2022.109677
Mapping biodiversity patterns across taxa and environments is crucial to address the evolutionary and ecological dimensions of species distribution, suggesting areas of particular importance for conservation purposes. Within Cactaceae, spatial diversity patterns are poorly explored, as are the abiotic factors that may predict these patterns. We gathered geographic and genetic data from 921 cactus species by exploring both the occurrence and genetic databases, which are tightly associated with drylands, to evaluate diversity patterns, such as phylogenetic diversity and endemism, paleo-, neo-, and superendemism, and the environmental predictor variables of such patterns in a global analysis. Hotspot areas of cacti diversity are scattered along the Neotropical and Nearctic regions, mainly in the desertic portion of Mesoamerica, Caribbean Island, and the dry diagonal of South America. The geomorphological features of these regions may create a complexity of areas that work as locally buffered zones over time, which triggers local events of diversification and speciation. Desert and dryland/dry forest areas comprise paleo- and superendemism and may act as both museums and cradles of species, displaying great importance for conservation. Past climates, topography, soil features, and solar irradiance seem to be the main predictors of distinct endemism types. The hotspot areas that encompass a major part of the endemism cells are outside or poorly covered by formal protection units. The current legally protected areas are not able to conserve the evolutionary diversity of cacti. Given the rapid anthropogenic disturbance, efforts must be reinforced to monitor biodiversity and the environment and to define/plan current and new protected areas.
Hidalgo-Triana, N., F. Casimiro-Soriguer Solanas, A. Solakis Tena, A. V. Pérez-Latorre, and J. García-Sánchez. 2022. Melinis repens (Willd.) Zizka subsp. repens (Poaceae) in Europe: distribution, ecology and potential invasion. Botany Letters 169: 390–399. https://doi.org/10.1080/23818107.2022.2080111
Melinis repens subsp. repens is an annual herb native to Africa and southwestern Asia. In 2008, this species was detected growing in road verges and showing a reduced occupancy area of 6 km2 in a natural area of the southern Iberian Peninsula in the province of Malaga (Andalusia, Spain). The rest of the existing European records of this species comes from the Czech Republic, the Italian Peninsula, and Great Britain and can be considered casual. Furthermore, this species has become naturalised in Sardinia. The aim of this work is to study the invasion status, habitats, potential impacts, invasive behaviour, and pathways of introduction of Melinis repens subsp. repens in the southern Iberian Peninsula (Spain) to contribute to the control of this species. This species was most probably introduced into Europe for ornamental, fodder, or slope stabilization purposes. Our field work revealed this species has become naturalised in several habitats of Malaga and Granada provinces (Andalusia) occupying an area of 263 km2 in 2021. It behaves as a pioneer species that colonizes disturbed road margins and occurs in the same habitat as Cenchrus setaceus. Melinis repens subsp. repens can become dominant in natural EUNIS habitats and can also occupy cultivated areas. Because of the high occupancy area detected, and because the species has been assigned to the European Union List of Invasive Alien Plants based on the EPPO prioritization process, this plant should be considered the object of a control programme and its use should be legally prohibited in Spain, and more largely in European Mediterranean areas.
Williams, C. J. R., D. J. Lunt, U. Salzmann, T. Reichgelt, G. N. Inglis, D. R. Greenwood, W. Chan, et al. 2022. African Hydroclimate During the Early Eocene From the DeepMIP Simulations. Paleoceanography and Paleoclimatology 37. https://doi.org/10.1029/2022pa004419
The early Eocene (∼56‐48 million years ago) is characterised by high CO2 estimates (1200‐2500 ppmv) and elevated global temperatures (∼10 to 16°C higher than modern). However, the response of the hydrological cycle during the early Eocene is poorly constrained, especially in regions with sparse data coverage (e.g. Africa). Here we present a study of African hydroclimate during the early Eocene, as simulated by an ensemble of state‐of‐the‐art climate models in the Deep‐time Model Intercomparison Project (DeepMIP). A comparison between the DeepMIP pre‐industrial simulations and modern observations suggests that model biases are model‐ and geographically dependent, however these biases are reduced in the model ensemble mean. A comparison between the Eocene simulations and the pre‐industrial suggests that there is no obvious wetting or drying trend as the CO2 increases. The results suggest that changes to the land sea mask (relative to modern) in the models may be responsible for the simulated increases in precipitation to the north of Eocene Africa. There is an increase in precipitation over equatorial and West Africa and associated drying over northern Africa as CO2 rises. There are also important dynamical changes, with evidence that anticyclonic low‐level circulation is replaced by increased south‐westerly flow at high CO2 levels. Lastly, a model‐data comparison using newly‐compiled quantitative climate estimates from palaeobotanical proxy data suggests a marginally better fit with the reconstructions at lower levels of CO2.
Reichgelt, T., D. R. Greenwood, S. Steinig, J. G. Conran, D. K. Hutchinson, D. J. Lunt, L. J. Scriven, and J. Zhu. 2022. Plant Proxy Evidence for High Rainfall and Productivity in the Eocene of Australia. Paleoceanography and Paleoclimatology 37. https://doi.org/10.1029/2022pa004418
During the early to middle Eocene, a mid‐to‐high latitudinal position and enhanced hydrological cycle in Australia would have contributed to a wetter and “greener” Australian continent where today arid to semi‐arid climates dominate. Here, we revisit 12 southern Australian plant megafossil sites from the early to middle Eocene to generate temperature, precipitation and seasonality paleoclimate estimates, net primary productivity (NPP) and vegetation type, based on paleobotanical proxies and compare to early Eocene global climate models. Temperature reconstructions are uniformly subtropical (mean annual, summer, and winter mean temperatures 19–21 °C, 25–27 °C and 14–16 °C, respectively), indicating that southern Australia was ∼5 °C warmer than today, despite a >20° poleward shift from its modern geographic location. Precipitation was less homogeneous than temperature, with mean annual precipitation of ∼60 cm over inland sites and >100 cm over coastal sites. Precipitation may have been seasonal with the driest month receiving 2–7× less than mean monthly precipitation. Proxy‐model comparison is favorable with an 1680 ppm CO2 concentration. However, individual proxy reconstructions can disagree with models as well as with each other. In particular, seasonality reconstructions have systemic offsets. NPP estimates were higher than modern, implying a more homogenously “green” southern Australia in the early to middle Eocene, when this part of Australia was at 48–64 °S, and larger carbon fluxes to and from the Australian biosphere. The most similar modern vegetation type is modern‐day eastern Australian subtropical forest, although distance from coast and latitude may have led to vegetation heterogeneity.
Figueiredo, P. H. A., A. Sánchez‐Tapia, M. F. de Siqueira, and J. B. B. Sansevero. 2022. Linking regeneration niche to monodominance in biodiverse tropical forest landscapes. Journal of Vegetation Science 33. https://doi.org/10.1111/jvs.13128
Aims Although monodominance has attracted the attention of ecologists for many decades, only a few studies have devoted attention to how abiotic factors could influence the occurrence of monodominant forest patches on the biome scale. Here, we assessed whether the occurrence of monodominant forest patches of Moquiniastrum polymorphum (Less.) G. Sancho (Asteraceae), an early successional tree species with wind-dispersed seeds, could be predicted by optimum germination temperature and past deforestation. We also verified in what edaphic and climatic conditions the species could reach monodominance; Location The Atlantic Forest, Brazil Methods We estimated the optimum germination temperature across the species’ geographic range as a function of annual mean temperature based on the results of germination tests available in the literature. Past deforestation (a proxy of suitable habitat for the species’ dispersal and establishment) around monodominant forest patches was estimated by calculating the forest cover in 1985. We also modeled the upper limit of the dominance (relative abundance) as a function of climatic and edaphic variables considered important for the species’ establishment. Results The results showed that the probability of occurrence of monodominant forest patches is statistically null in places where the germination time can take more than 10 days and the landscape had more than 20% of forest cover. The values of relative density at monodominant condition (> 60%) occurred only in warmer regions with infertile soils and median precipitation conditions (about 1,075 mm to 1,700 mm per year) in the Atlantic Forest. Conclusion We conclude that only under optimal conditions of germination and dispersal (i.e., regeneration niche) does monodominance occur. This highlights germination traits as an important mechanism for regulating monodominance. In addition, the approach used to predict regions with optimum germination temperature has further implications for understanding species abundance and distribution more generally.
Carvalho¹, C. E., M. O. T. Menezes, F. S. Araújo, and J. C. Sfair. 2022. High endemism of cacti remains unprotected in the Caatinga. Biodiversity and Conservation 31: 1217–1228. https://doi.org/10.1007/s10531-022-02384-y
Protected areas are one of the main strategies of biodiversity conservation. However, if these areas do not coincide spatially with priority areas for conservation, they may not fully achieve their objective. Cactaceae is one of the most frequent plant families in the drylands of the neotropical reg…
Cavalcante, A. de M. B., and A. C. P. Sampaio. 2022. Modeling the potential distribution of cacti under climate change scenarios in the largest tropical dry forest region in South America. Journal of Arid Environments 200: 104725. https://doi.org/10.1016/j.jaridenv.2022.104725
Climate change projections for the Brazilian semiarid region for the rest of this century include increased temperature, reduced precipitation and aridification. Consequently, alterations in the distribution of species are expected in the largest seasonally dry tropical forest in South America (Caat…
Xue, T., S. R. Gadagkar, T. P. Albright, X. Yang, J. Li, C. Xia, J. Wu, and S. Yu. 2021. Prioritizing conservation of biodiversity in an alpine region: Distribution pattern and conservation status of seed plants in the Qinghai-Tibetan Plateau. Global Ecology and Conservation 32: e01885. https://doi.org/10.1016/j.gecco.2021.e01885
The Qinghai-Tibetan Plateau (QTP) harbors abundant and diverse plant life owing to its high habitat heterogeneity. However, the distribution pattern of biodiversity hotspots and their conservation status remain unclear. Based on 148,283 high-resolution occurrence coordinates of 13,450 seed plants, w…