University of New Caledonia

of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.

AT A MEETING OF WORLD MANGROVE EXPERTS HELD LAST YEAR IN Australia, it was unanimously agreed that we face the prospect of a world deprived of the services offered by mangrove ecosystems, perhaps within the next 100 years. We are greatly concerned that the full implications of mangrove loss for humankind are not fully appreciated. Growing pressures of urban and industrial developments along coastlines, combined with climate change and sealevel rise, urge the need to conserve, protect, and restore tidal wetlands. Effective governance structures, socioeconomic risk policies, and education strategies are needed now to enable societies around the world to reverse the trend of mangrove loss and ensure that future generations enjoy the ecosystem services provided by such valuable natural ecosystems.

Amborella trichopoda is strongly supported as the single living species of the sister lineage to all other extant flowering plants, providing a unique reference for inferring the genome content and structure of the most recent common ancestor (MRCA) of living angiosperms. Sequencing the Amborella genome, we identified an ancient genome duplication predating angiosperm diversification, without evidence of subsequent, lineage-specific genome duplications. Comparisons between Amborella and other angiosperms facilitated reconstruction of the ancestral angiosperm gene content and gene order in the MRCA of core eudicots. We identify new gene families, gene duplications, and floral protein-protein interactions that first appeared in the ancestral angiosperm. Transposable elements in Amborella are ancient and highly divergent, with no recent transposon radiations. Population genomic analysis across Amborella's native range in New Caledonia reveals a recent genetic bottleneck and geographic structure with conservation implications.

Seasonal records of tropical sea-surface temperature (SST) over the past 10(5) years can be recovered from high-precision measurements of coral strontium/calcium ratios with the use of thermal ionization mass spectrometry. The temperature dependence of these ratios was calibrated with corals collected at SST recording stations and by (18)O/(16)O thermometry. The results suggest that mean monthly SST may be determined with an apparent accuracy of better than 0.5 degrees C. Measurements on a fossil coral indicate that 10,200 years ago mean annual SSTs near Vanuatu in the southwestern Pacific Ocean were about 5 degrees C colder than today and that seasonal variations in SST were larger. These data suggest that tropical climate zones were compressed toward the equator during deglaciation.

Sebertia acuminata (Sapotaceae) from New Caledonia has been shown to be a hyperaccumulator of nickel. The nickel content of the latex (25.74 percent on a dry weight basis) is easily the highest nickel concentration ever found in living material. The nickel is in the form of a low-molecular-weight, water-soluble organic complex.

Abstract Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system 1 . Remote-sensing estimates to quantify carbon losses from global forests 2–5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced 6 and satellite-derived approaches 2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea 2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.

Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas.

Research Article| April 01, 2013 Nickel Laterite Ore Deposits: Weathered Serpentinites Charles R. M. Butt; Charles R. M. Butt 1CSIRO Earth Science and Resource EngineeringBox 1130, Bentley, Western Australia 6102E-mail: Charles.Butt@csiro.au Search for other works by this author on: GSW Google Scholar Dominique Cluzel Dominique Cluzel 2Pôle Pluridisciplinaire de la Matière et de l'Environnement, Université de la Nouvelle-Calédonie, BP R4, 98850 Nouméa, Nouvelle-CalédonieE-mail: dominique.cluzel@univ-nc.nc Search for other works by this author on: GSW Google Scholar Elements (2013) 9 (2): 123–128. https://doi.org/10.2113/gselements.9.2.123 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Charles R. M. Butt, Dominique Cluzel; Nickel Laterite Ore Deposits: Weathered Serpentinites. Elements 2013;; 9 (2): 123–128. doi: https://doi.org/10.2113/gselements.9.2.123 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyElements Search Advanced Search Abstract Nickel laterite ores account for over 60% of global nickel supply. They are the product of intensive deep weathering of serpentinites under humid tropical conditions. Nickel is concentrated to over 1.0 wt% and is hosted in a variety of secondary oxides, hydrous Mg silicates and smectites. The formation, mineralogy and grade of the deposits are controlled by the interplay of lithology, tectonics, climate and geomorphology. Most deposits have a multi-phase development, evolving as their climatic and/or topographic environment change. The richest deposits (>3 wt% Ni) formed where oxide-rich regoliths were uplifted and Ni leached downwards to concentrate in neo-formed silicates in the saprolite. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Phytomining technology employs hyperaccumulator plants to take up metal in harvestable plant biomass. Harvesting, drying and incineration of the biomass generates a high-grade bio-ore. We propose that "agromining" (a variant of phytomining) could provide local communities with an alternative type of agriculture on degraded lands; farming not for food crops, but for metals such as nickel (Ni). However, two decades after its inception and numerous successful experiments, commercial phytomining has not yet become a reality. To build the case for the minerals industry, a large-scale demonstration is needed to identify operational risks and provide "real-life" evidence for profitability.

The internal transcribed spacers and the 5.8S coding region of nuclear ribosomal DNA were sequenced and analyzed to address questions of generic relationships in Winteraceae. The molecular data generated a single tree that is congruent with one based on morphological data. The sequences of ITS 1 in the family range from 235 to 252 bases in size and of ITS 2 from 213 to 226 bases. The size of the 5.8S coding region is 164 bases. The range of ITS 1 and ITS 2 sequence divergence between pairs of genera within Winteraceae is relatively low in comparison to other plant families. Two types of ITS 1 and ITS 2 sequences were observed in the same individual for some taxa. Sequence variations between the two arrays are 4.7%–6.3% for ITS 1 and 5.1%–7.0% for ITS 2. Both arrays of sequences, however, generate the same phylogenetic relationships. Rates of nucleotide substitutions for the internal transcribed spacers are 3.2–5.2 × 10 ‐10 substitution per site per year estimated in ITS 1 and 3.6–5.7 × 10 ‐10 in ITS 2.

In this paper, we propose a novel accurate method for dead-reckoning of wheeled vehicles based only on an Inertial Measurement Unit (IMU). In the context of intelligent vehicles, robust and accurate dead-reckoning based on the IMU may prove useful to correlate feeds from imaging sensors, to safely navigate through obstructions, or for safe emergency stops in the extreme case of exteroceptive sensors failure. The key components of the method are the Kalman filter and the use of deep neural networks to dynamically adapt the noise parameters of the filter. The method is tested on the KITTI odometry dataset, and our dead-reckoning inertial method based only on the IMU accurately estimates 3D position, velocity, orientation of the vehicle and self-calibrates the IMU biases. We achieve on average a 1.10% translational error and the algorithm competes with top-ranked methods which, by contrast, use LiDAR or stereo vision.

Coral reefs provide ecosystem goods and services for millions of people in the tropics, but reef conditions are declining worldwide. Effective solutions to the crisis facing coral reefs depend in part on understanding the context under which different types of conservation benefits can be maximized. Our global analysis of nearly 1,800 tropical reefs reveals how the intensity of human impacts in the surrounding seascape, measured as a function of human population size and accessibility to reefs ("gravity"), diminishes the effectiveness of marine reserves at sustaining reef fish biomass and the presence of top predators, even where compliance with reserve rules is high. Critically, fish biomass in high-compliance marine reserves located where human impacts were intensive tended to be less than a quarter that of reserves where human impacts were low. Similarly, the probability of encountering top predators on reefs with high human impacts was close to zero, even in high-compliance marine reserves. However, we find that the relative difference between openly fished sites and reserves (what we refer to as conservation gains) are highest for fish biomass (excluding predators) where human impacts are moderate and for top predators where human impacts are low. Our results illustrate critical ecological trade-offs in meeting key conservation objectives: reserves placed where there are moderate-to-high human impacts can provide substantial conservation gains for fish biomass, yet they are unlikely to support key ecosystem functions like higher-order predation, which is more prevalent in reserve locations with low human impacts.

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate.

BACKGROUND: Biofloc technology (BFT), a rearing method with little or no water exchange, is gaining popularity in aquaculture. In the water column, such systems develop conglomerates of microbes, algae and protozoa, together with detritus and dead organic particles. The intensive microbial community presents in these systems can be used as a pond water quality treatment system, and the microbial protein can serve as a feed additive. The current problem with BFT is the difficulty of controlling its bacterial community composition for both optimal water quality and optimal shrimp health. The main objective of the present study was to investigate microbial diversity of samples obtained from different culture environments (Biofloc technology and clear seawater) as well as from the intestines of shrimp reared in both environments through high-throughput sequencing technology. RESULTS: Analyses of the bacterial community identified in water from BFT and "clear seawater" (CW) systems (control) containing the shrimp Litopenaeus stylirostris revealed large differences in the frequency distribution of operational taxonomic units (OTUs). Four out of the five most dominant bacterial communities were different in both culture methods. Bacteria found in great abundance in BFT have two principal characteristics: the need for an organic substrate or nitrogen sources to grow and the capacity to attach to surfaces and co-aggregate. A correlation was found between bacteria groups and physicochemical and biological parameters measured in rearing tanks. Moreover, rearing-water bacterial communities influenced the microbiota of shrimp. Indeed, the biofloc environment modified the shrimp intestine microbiota, as the low level (27 %) of similarity between intestinal bacterial communities from the two treatments. CONCLUSION: This study provides the first information describing the complex biofloc microbial community, which can help to understand the environment-microbiota-host relationship in this rearing system.

The demand for natural products isolated from microalgae has increased over the last decade and has drawn the attention from the food, cosmetic and nutraceutical industries. Among these natural products, the demand for natural antioxidants as an alternative to synthetic antioxidants has increased. In addition, microalgae combine several advantages for the development of biotechnological applications: high biodiversity, photosynthetic yield, growth, productivity and a metabolic plasticity that can be orientated using culture conditions. Regarding the wide diversity of antioxidant compounds and mode of action combined with the diversity of reactive oxygen species (ROS), this review covers a brief presentation of antioxidant molecules with their role and mode of action, to summarize and evaluate common and recent assays used to assess antioxidant activity of microalgae. The aim is to improve our ability to choose the right assay to assess microalgae antioxidant activity regarding the antioxidant molecules studied.

Abstract Trends (1961–2003) in daily maximum and minimum temperatures, extremes and variance were found to be spatially coherent across the Asia–Pacific region. The majority of stations exhibited significant trends: increases in mean maximum and mean minimum temperature, decreases in cold nights and cool days, and increases in warm nights. No station showed a significant increase in cold days or cold nights, but a few sites showed significant decreases in hot days and warm nights. Significant decreases were observed in both maximum and minimum temperature standard deviation in China, Korea and some stations in Japan (probably reflecting urbanization effects), but also for some Thailand and coastal Australian sites. The South Pacific convergence zone (SPCZ) region between Fiji and the Solomon Islands showed a significant increase in maximum temperature variability. Correlations between mean temperature and the frequency of extreme temperatures were strongest in the tropical Pacific Ocean from French Polynesia to Papua New Guinea, Malaysia, the Philippines, Thailand and southern Japan. Correlations were weaker at continental or higher latitude locations, which may partly reflect urbanization. For non‐urban stations, the dominant distribution change for both maximum and minimum temperature involved a change in the mean, impacting on one or both extremes, with no change in standard deviation. This occurred from French Polynesia to Papua New Guinea (except for maximum temperature changes near the SPCZ), in Malaysia, the Philippines, and several outlying Japanese islands. For urbanized stations the dominant change was a change in the mean and variance, impacting on one or both extremes. This result was particularly evident for minimum temperature. The results presented here, for non‐urban tropical and maritime locations in the Asia–Pacific region, support the hypothesis that changes in mean temperature may be used to predict changes in extreme temperatures. At urbanized or higher latitude locations, changes in variance should be incorporated. Copyright © 2005 Royal Meteorological Society.

Abstract There is growing interest among conservationists in biodiversity mapping based on stacked species distribution models ( SSDM s), a method that combines multiple individual species distribution models to produce a community‐level model. However, no user‐friendly interface specifically designed to provide the basic tools needed to fit such models was available until now. The “ ssdm ” package is a computer platform implemented in r providing a range of methodological approaches and parameterisation at each step in building the SSDM : e.g. pseudo‐absence selection, variable contribution and model accuracy assessment, inter‐model consensus forecasting, species assembly design, and calculation of weighted endemism. The object‐oriented design of the package is such that: users can modify existing methods, extend the framework by implementing new methods, and share them to be reproduced by others. The package includes a graphical user interface to extend the use of SSDM s to a wide range of conservation scientists and practitioners.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.

Research Article| February 01, 1997 Acidic and sulfate-rich hydrothermal fluids from the Manus back-arc basin, Papua New Guinea Toshitaka Gamo; Toshitaka Gamo 1Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Kei Okamura; Kei Okamura 1Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Jean-Luc Charlou; Jean-Luc Charlou 2IFREMER/Centre de Brest, B.P. 70, 29280 Plouzane Cedex, France Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Tetsuro Urabe; Tetsuro Urabe 3Geological Survey of Japan, Tsukuba, Ibaraki 305, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Jean-Marie Auzende; Jean-Marie Auzende 2IFREMER/Centre de Brest, B.P. 70, 29280 Plouzane Cedex, France4ORSTOM/IFREMER (Noumea), B.P. A5, Noumea Cedex, New Caledonia Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Junichiro Ishibashi; Junichiro Ishibashi 5Laboratory for Earthquake Chemistry, University of Tokyo, Hongo, Tokyo 113, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Kiminori Shitashima; Kiminori Shitashima 6Central Research Institute of Electric Power Industry, Abiko, Chiba 270-11, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise; Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Hitoshi Chiba; Hitoshi Chiba 7Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party of the ManusFlux Cruise Shipboard Scientific Party of the ManusFlux Cruise Search for other works by this author on: GSW Google Scholar Author and Article Information Toshitaka Gamo 1Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164, Japan Shipboard Scientific Party of the ManusFlux Cruise Kei Okamura 1Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164, Japan Shipboard Scientific Party of the ManusFlux Cruise Jean-Luc Charlou 2IFREMER/Centre de Brest, B.P. 70, 29280 Plouzane Cedex, France Shipboard Scientific Party of the ManusFlux Cruise Tetsuro Urabe 3Geological Survey of Japan, Tsukuba, Ibaraki 305, Japan Shipboard Scientific Party of the ManusFlux Cruise Jean-Marie Auzende 2IFREMER/Centre de Brest, B.P. 70, 29280 Plouzane Cedex, France4ORSTOM/IFREMER (Noumea), B.P. A5, Noumea Cedex, New Caledonia Shipboard Scientific Party of the ManusFlux Cruise Junichiro Ishibashi 5Laboratory for Earthquake Chemistry, University of Tokyo, Hongo, Tokyo 113, Japan Shipboard Scientific Party of the ManusFlux Cruise Kiminori Shitashima 6Central Research Institute of Electric Power Industry, Abiko, Chiba 270-11, Japan Shipboard Scientific Party of the ManusFlux Cruise Hitoshi Chiba 7Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812, Japan Shipboard Scientific Party of the ManusFlux Cruise Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (2): 139–142. https://doi.org/10.1130/0091-7613(1997)025<0139:AASRHF>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Toshitaka Gamo, Kei Okamura, Jean-Luc Charlou, Tetsuro Urabe, Jean-Marie Auzende, Junichiro Ishibashi, Kiminori Shitashima, Hitoshi Chiba; Shipboard Scientific Party of the ManusFlux Cruise, Acidic and sulfate-rich hydrothermal fluids from the Manus back-arc basin, Papua New Guinea. Geology 1997;; 25 (2): 139–142. doi: https://doi.org/10.1130/0091-7613(1997)025<0139:AASRHF>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Hot (≥ 88-120 °C) and acidic (pH ≤ 2.1) hydrothermal fluids rich in sulfate were discovered venting in the DESMOS caldera (depth = 1926 m), eastern Manus back-arc basin, Bismarck Sea, surrounded by Papua New Guinea. The abundant sulfate (≥ 32.8 mM, higher than the seawater value of 28 mM) with elemental sulfur deposition around the vents, and remarkably low δD(H2O) and δ 34S(H2S) values (−8.1‰ and −5.6‰, respectively), are suggestive of the incorporation of a magmatic fluid and the disproportionation of the exsolved SO2 from a magma body. The DESMOS fluid may be similar in origin to the acidic sulfate-chloride hot springs associated with subaerial volcanic activity. In contrast to the typical hydrothermal end member Mg concentration of 0, the DESMOS fluids are rich in Mg (46–52 mM), probably because of Mg dissolution by acid attack upon magnesium silicate minerals. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Summary Xylem vulnerability to embolism is emerging as a major factor in drought‐induced tree mortality events across the globe. However, we lack understanding of how and to what extent climate has shaped vascular properties or functions. We investigated the evolution of xylem hydraulic function and diversification patterns in Australia's most successful gymnosperm clade, Callitris , the world's most drought‐resistant conifers. For all 23 species in this group, we measured embolism resistance ( P 50 ), xylem specific hydraulic conductivity ( K s ), wood density, and tracheary element size from natural populations. We investigated whether hydraulic traits variation linked with climate and the diversification of this clade using a time‐calibrated phylogeny. Embolism resistance varied widely across the Callitris clade ( P 50 : −3.8 to −18.8 MP a), and was significantly related to water scarcity, as was tracheid diameter. We found no evidence of a safety‐efficiency tradeoff; K s and wood density were not related to rainfall. Callitris diversification coincides with the onset of aridity in Australia since the early Oligocene. Our results highlight the evolutionary lability of xylem traits with climate, and the leading role of aridity in the diversification of conifers. The uncoupling of safety from other xylem functions allowed Callitris to evolve extreme embolism resistance and diversify into xeric environments.