Science Rendue Possible
Ramirez-Villegas, J., C. K. Khoury, H. A. Achicanoy, M. V. Diaz, A. C. Mendez, C. C. Sosa, Z. Kehel, et al. 2022. State of ex situ conservation of landrace groups of 25 major crops. Nature Plants 8: 491–499. https://doi.org/10.1038/s41477-022-01144-8
Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation. By analysing the state of representation of traditional varieties of 25 major crops in ex situ repositories, this study demonstrates conservation progress made over more than a half-century and identifies the gaps remaining to be filled.
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.
Chevalier, M. 2022. &lt;i&gt;crestr&lt;/i&gt;: an R package to perform probabilistic climate reconstructions from palaeoecological datasets. Climate of the Past 18: 821–844. https://doi.org/10.5194/cp-18-821-2022
Abstract. Statistical climate reconstruction techniques are fundamental tools to study past climate variability from fossil proxy data. In particular, the methods based on probability density functions (or PDFs) can be used in various environments and with different climate proxies because they rely on elementary calibration data (i.e. modern geolocalised presence data). However, the difficulty of accessing and curating these calibration data and the complexity of interpreting probabilistic results have often limited their use in palaeoclimatological studies. Here, I introduce a new R package (crestr) to apply the PDF-based method CREST (Climate REconstruction SofTware) on diverse palaeoecological datasets and address these problems. crestr includes a globally curated calibration dataset for six common climate proxies (i.e. plants, beetles, chironomids, rodents, foraminifera, and dinoflagellate cysts) associated with an extensive range of climate variables (20 terrestrial and 19 marine variables) that enables its use in most terrestrial and marine environments. Private data collections can also be used instead of, or in combination with, the provided calibration dataset. The package includes a suite of graphical diagnostic tools to represent the data at each step of the reconstruction process and provide insights into the effect of the different modelling assumptions and external factors that underlie a reconstruction. With this R package, the CREST method can now be used in a scriptable environment and thus be more easily integrated with existing workflows. It is hoped that crestr will be used to produce the much-needed quantified climate reconstructions from the many regions where they are currently lacking, despite the availability of suitable fossil records. To support this development, the use of the package is illustrated with a step-by-step replication of a 790 000-year-long mean annual temperature reconstruction based on a pollen record from southeastern Africa.
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.
Okamura, Y., A. Sato, L. Kawaguchi, A. J. Nagano, M. Murakami, H. Vogel, and J. Kroymann. 2022. Microevolution of Pieris butterfly genes involved in host plant adaptation along a host plant community cline. Molecular Ecology 31: 3083–3097. https://doi.org/10.1111/mec.16447
Herbivorous insects have evolved counteradaptations to overcome the chemical defenses of their host plants. Several of these counteradaptations have been elucidated at the molecular level, in particular for insects specialized on cruciferous host plants. While the importance of these counteradaptations for host plant colonization is well established, little is known about their microevolutionary dynamics in the field. In particular, it is not known whether and how host plant diversity shapes diversity in insect counteradaptations. In this study, we examine patterns of host plant use and insect counteradaptation in three Pieris butterfly species across Japan. The larvae of these butterflies express nitrile‐specifier protein (NSP) and its paralog major allergen (MA) in their gut to overcome the highly diversified glucosinolate‐myrosinase defense system of their cruciferous host plants. Pieris napi and Pieris melete colonize wild Brassicaceae whereas Pieris rapae typically uses cultivated Brassica as a host, regardless of the local composition of wild crucifers. As expected, NSP and MA diversity was independent of the local composition of wild Brassicaceae in P. rapae. In contrast, NSP diversity correlated with local host plant diversity in both species that preferred wild Brassicaceae. P. melete and P. napi both revealed two distinct major NSP alleles, which shaped diversity among local populations, albeit with different evolutionary trajectories. In comparison, MA showed no indication for local adaptation. Altogether, MA appeared to be evolutionary more conserved than NSP, suggesting that both genes play different roles in diverting host plant chemical defense.
Joshi, M. D., and C. Joshi. 2022. Areas of species diversity and endemicity of Nepal. Ecosphere 13. https://doi.org/10.1002/ecs2.3969
In this study, we analyzed the distribution and the spatial pattern of species diversity of vascular plants in Nepal. The aim was to identify and evaluate the occurrence and status of species‐rich areas in Nepal using ecological and environmental drivers. We used 52,973 georeferenced herbarium specimen records, representing 2650 species collected from Nepal. Altogether, 41 environmental variables were used for model development and validation. We used MaxEnt to predict the distribution pattern. All the significant species distribution predictions were then used to develop a species richness and endemism pattern in Nepal. The High Mountain and Himalaya, particularly east and central Nepal, were found to be species diverse and endemically rich areas, whereas western Nepal had lower species richness. We observed that isothermality, slope, rugosity, potential evapotranspiration, precipitation of humid months, temperature annual range, mean diurnal range, and normalized difference in vegetation index of humid months were the most influential environmental and climatic variables. We observed that about 60% of the areas, which had highest richness and endemism values, are still not included in protected areas in Nepal. We quantitatively analyzed the species richness and endemicity patterns of Nepal and were able to identify 19 areas of high species diversity and endemicity, six of which are newly identified.
Yousefi, M., A. Mahmoudi, A. Kafash, A. Khani, and B. Kryštufek. 2022. Biogeography of rodents in Iran: species richness, elevational distribution and their environmental correlates. Mammalia 86: 309–320. https://doi.org/10.1515/mammalia-2021-0104
Abstract Rodent biogeographic studies are disproportionately scarce in Iran, however, they are an ideal system to understand drivers of biodiversity distributions in the country. The aims of the present research are to determine (i) the pattern of rodent richness across the country, (ii) quantify th…
Li, L., X. Xu, H. Qian, X. Huang, P. Liu, J. B. Landis, Q. Fu, et al. 2022. Elevational patterns of phylogenetic structure of angiosperms in a biodiversity hotspot in eastern Himalaya Y. Qu [ed.],. Diversity and Distributions. https://doi.org/10.1111/ddi.13513
Aims The tropical niche conservatism (TNC) hypothesis and the out of the tropics (OTT) hypothesis propose mechanisms generating patterns of species diversity across warm-to-cold thermal gradients at large spatial scales. These two hypotheses both integrate ecological and biogeography-related evoluti…
Filartiga, A. L., A. Klimeš, J. Altman, M. P. Nobis, A. Crivellaro, F. Schweingruber, and J. Doležal. 2022. Comparative anatomy of leaf petioles in temperate trees and shrubs: the role of plant size, environment and phylogeny. Annals of Botany 129: 567–582. https://doi.org/10.1093/aob/mcac014
Background and Aims Petioles are important plant organs connecting stems with leaf blades and affecting light-harvesting ability of the leaf as well as transport of water, nutrients and biochemical signals. Despite the high diversity in petiole size, shape and anatomy, little information is availabl…