Search

Evolutionary shifts in breeding system are thought to have played key roles in the diversification of many lineages of plants, including the evening primrose family (Onagraceae), which includes the genus Oenothera L. Diversification in Oenothera has been accompanied by frequent breeding system shifts, but it is not clear whether these differences are due to shared evolutionary history or reflect repeated independent adaptations to varying ecological conditions. In this study, we focus on “Subclade B,” one of two primary clades within Oenothera, and combine phylogenetic reconstructions and breeding system data to evaluate evidence for multiple transitions to self-compatibility. This study includes 46 of the 58 named taxa (species and subspecies) of Oenothera Subclade B. Some taxa were sequenced in earlier analyses, available from GenBank, one was resampled here to add new sequences, and 28 taxa are newly sequenced here. We base our phylogeny on sequencing of portions of four chloroplast markers (rps16, ndhF, trnL-F, and rbcL) and two nuclear genes (ITS and ETS). We used pollination tests to verify or determine the breeding system of these taxa. Our phylogeny supports the current classification of Oenothera with minor changes and provides greater insight and clarity to the relationships of these species. Our results provide support for the monophyly of most of the sections in Oenothera Subclade B, as well as greater resolution for topology within sections Gaura (L.) W. L. Wagner & Hoch, Hartmannia (Spach) Walpers, Kneiffia (Spach) Walpers, and Megapterium (Spach) Walpers. Relationships among these monophyletic lineages, and the placement of sections Paradoxus W. L. Wagner and Peniophyllum (Pennell) Munz, and of the allopolypoid O. hispida (Benth.) W. L. Wagner, Hoch & Zarucchi, are not uniformly well-supported and need further clarification, but these phylogenetic uncertainties had minimal impact on the inference of transitions in self-compatibility in Subclade B. We use maximum likelihood, Bayesian inference and stochastic character mapping to estimate the minimum and maximum number of transitions necessary to explain the phylogenetic distribution of self-compatible lineages. Our results confirm at least 12 and possibly up to 15 independent transitions from self-incompatibility to self-compatibility in Oenothera Subclade B. This lability in breeding system, which is also seen broadly across Oenothera, lends strong support to the hypothesis that this trait plays a key role in the diversification of the genus.

As humanity’s demand on natural resources is increasingly exceeding Earth’s biological rate of regeneration, environmental deterioration such as greenhouse gas accumulation in the atmosphere, ocean acidification and groundwater depletion is accelerating. As a result, the capacity of ecosystems to renew biomass, herein referred to as ‘biocapacity’, is becoming the material bottleneck for the human economy. Yet, economic development theory and practice continue to underplay the importance of natural resources, most notably biological ones. We analysed the unequal exposure of national economies to biocapacity constraints. We found that a growing number of people live in countries with both biocapacity deficits and below-average income. Low income thwarts these economies’ ability to compete for needed resources on the global market. By 2017, 72% of humanity lived in such countries. This trend not only erodes their possibilities for maintaining progress but also eliminates their chances for eradicating poverty, a situation we call an ‘ecological poverty trap’. An analysis of national economies’ unequal exposure to biocapacity constraints and purchasing power reveals how increasing demand of natural resources can lead to inescapable poverty traps.

The growth of life on Earth over more than 4 billion years has experienced five major extinction events, each followed by a period of rapid increase in species number. When organisms first invaded the land about 480 million years ago, another explosive proliferation of species followed. Our species, Homo sapiens , appeared some 300 000 years ago, developed agriculture about 11 000 years ago and grew rapidly to some 7.8 billion people, who are currently consuming about 175% of the sustainable productivity available worldwide. By mid-century (2050), we will have grown to about 9.9 billion. Wealth is very unequally distributed. Meanwhile, the Earth's mean temperature has increased by 1.1°C above pre-industrial levels, and we are on track for a total increase of 2.6 to 3.9°C. We are driving species to extinction at a rate unprecedented for the past 66 million years. These changes promise to be disastrous for the maintenance of civilization. Indeed, our only hope for a sustainable future will be for us to find a way to overcome our unremitting greed at all levels and to love one another while building social justice. This article is part of the theme issue ‘Ecological complexity and the biosphere: the next 30 years’.

A checklist of the grasses of India is presented, as compiled from survey of all available literature. Of the twelve subfamilies of grasses, ten are represented in India. Most subfamilies have been examined by taxonomic experts for up-to-date nomenclature. The list includes 1506 species plus infraspecific taxa and presents information on types, synonyms, distribution within India, and habit. Twelve new combinations are made, viz.Arctopoa tibetica(Munro ex Stapf) Prob. var.aristulata(Stapf) E.A. Kellogg,comb. nov.;Chimonocalamus nagalandianus(H.B. Naithani) L.G. Clark,comb. nov.;Chionachne digitata(L.f.) E.A. Kellogg,comb. nov.;Chionachne wallichiana(Nees) E.A. Kellogg,comb. nov.;Dinebra polystachyos (R. Br.) E.A. Kellogg,comb. nov.;Moorochloa eruciformis(Sm.) Veldkamp var.divaricata(Basappa & Muniv.) E.A. Kellogg,comb. nov.;Phyllostachys nigra(Lodd. ex Lindl.) Munro var.puberula(Miq.) Kailash,comb. & stat. nov.;Tzveleviochloa schmidii(Hook. f.) E.A. Kellogg,comb. nov.;Urochloa lata(Schumach.) C.E. Hubb. var.pubescens(C.E. Hubb.) E.A. Kellogg,comb. nov.;Urochloa ramosa(L.) T.Q. Nguyen var.pubescens(Basappa & Muniy.) E.A. Kellogg,comb. nov.;Urochloa semiundulata(Hochst. ex A. Rich.) Ashalatha & V.J. Nair var.intermedia(Basappa & Muniy.) E.A. Kellogg,comb. nov.

Human beings are not only a part of our planet's ecosystems, but also, they are massively overusing them. This makes ecosystem protection, including biodiversity preservation, vital for humanity's future. The speed and scale of the threat are unprecedented in human history. The long arch of evolution has been confronted with such a high level of human impact, that we are now facing the sixth mass extinction event, 66 million years after the last one. This threat heightens the imperative for bold human intervention. Our paper identifies three strategies for such an intervention. First, and possibly most challenging, human demand needs to be curbed so it fits within the bounds of what Earth's ecosystems can renew. Without meeting this quantitative goal, biodiversity preservation efforts will not be able to get scaled. Second, in the transition time, we must focus on those locations and areas where most biodiversity is concentrated. Such a focus on 'hotspots' will help safeguard the largest portion of biodiversity with least effort. Third, to direct biodiversity preservation strategies, we need to much better document the existence and distribution of biodiversity around the globe. New information technologies could help with this critical effort. In conclusion, biodiversity preservation is no longer just a concern for specialized biologist but is becoming a societal necessity if humanity wants to have a stable future.

Significance The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilization, because it is irreversible. Thousands of populations of critically endangered vertebrate animal species have been lost in a century, indicating that the sixth mass extinction is human caused and accelerating. The acceleration of the extinction crisis is certain because of the still fast growth in human numbers and consumption rates. In addition, species are links in ecosystems, and, as they fall out, the species they interact with are likely to go also. In the regions where disappearing species are concentrated, regional biodiversity collapses are likely occurring. Our results reemphasize the extreme urgency of taking massive global actions to save humanity’s crucial life-support systems., The ongoing sixth mass species extinction is the result of the destruction of component populations leading to eventual extirpation of entire species. Populations and species extinctions have severe implications for society through the degradation of ecosystem services. Here we assess the extinction crisis from a different perspective. We examine 29,400 species of terrestrial vertebrates, and determine which are on the brink of extinction because they have fewer than 1,000 individuals. There are 515 species on the brink (1.7% of the evaluated vertebrates). Around 94% of the populations of 77 mammal and bird species on the brink have been lost in the last century. Assuming all species on the brink have similar trends, more than 237,000 populations of those species have vanished since 1900. We conclude the human-caused sixth mass extinction is likely accelerating for several reasons. First, many of the species that have been driven to the brink will likely become extinct soon. Second, the distribution of those species highly coincides with hundreds of other endangered species, surviving in regions with high human impacts, suggesting ongoing regional biodiversity collapses. Third, close ecological interactions of species on the brink tend to move other species toward annihilation when they disappear—extinction breeds extinctions. Finally, human pressures on the biosphere are growing rapidly, and a recent example is the current coronavirus disease 2019 (Covid-19) pandemic, linked to wildlife trade. Our results reemphasize the extreme urgency of taking much-expanded worldwide actions to save wild species and humanity’s crucial life-support systems from this existential threat.

Major declines in insect biomass and diversity, reviewed here, have become obvious and well documented since the end of World War II. Here, we conclude that the spread and intensification of agriculture during the past half century is directly related to these losses. In addition, many areas, including tropical mountains, are suffering serious losses because of climate change as well. Crops currently occupy about 11% of the world’s land surface, with active grazing taking place over an additional 30%. The industrialization of agriculture during the second half of the 20th century involved farming on greatly expanded scales, monoculturing, the application of increasing amounts of pesticides and fertilizers, and the elimination of interspersed hedgerows and other wildlife habitat fragments, all practices that are destructive to insect and other biodiversity in and near the fields. Some of the insects that we are destroying, including pollinators and predators of crop pests, are directly beneficial to the crops. In the tropics generally, natural vegetation is being destroyed rapidly and often replaced with export crops such as oil palm and soybeans. To mitigate the effects of the Sixth Mass Extinction event that we have caused and are experiencing now, the following will be necessary: a stable (and almost certainly lower) human population, sustainable levels of consumption, and social justice that empowers the less wealthy people and nations of the world, where the vast majority of us live, will be necessary.

To evaluate the phylogenetic patterns of the distribution and evolution of plant secondary metabolites (PSMs), we selected 8 classes of PSMs and mapped them onto an updated phylogenetic tree including 437 families of seed plants. A significant phylogenetic signal was detected in 17 of the 18 tested seed-plant clades for at least 1 of the 8 PSM classes using the D statistic. The phylogenetic signal, nevertheless, indicated weak clustering of PSMs compared to a random distribution across all seed plants. The observed signal suggests strong diversifying selection during seed-plant evolution and/or relatively weak evolutionary constraints on the evolution of PSMs. In the survey of the current phylogenetic distributions of PSMs, we found that multiple origins of PSM biosynthesis due to external selective forces for diverse genetic pathways may have played important roles. In contrast, a single origin of PSMs seems rather uncommon. The distribution patterns for PSMs observed in this study may also be useful in the search for natural compounds for medicinal purposes.

Sciodaphyllum zarucchii M. M. Mora, Lowry, Idárraga, Jiménez-Mont. & G. M. Plunkett (Araliaceae) is described as a new species in honor of James L. Zarucchi (1952–2019). It occurs in humid premontane and montane forests on the western slope of the Cordillera Occidental in the department of Antioquia, Colombia, where it is known from only two localities, one of which is highly threatened by forest clearing. A risk of extinction assessment using the IUCN Red List criteria reveals that S. zarucchii is Endangered.

We compare the numbers of vascular plant species in the three major tropical areas. The Afrotropical Region (Africa south of the Sahara Desert plus Madagascar), roughly equal in size to the Latin American Region (Mexico southward), has only 56,451 recorded species (about 170 being added annually), as compared with 118,308 recorded species (about 750 being added annually) in Latin America. Southeast Asia, only a quarter the size of the other two tropical areas, has approximately 50,000 recorded species, with an average of 364 being added annually. Thus, Tropical Asia is likely to be proportionately richest in plant diversity, and for biodiversity in general, for its size. In the animal groups we reviewed, the patterns of species diversity were mostly similar except for mammals and butterflies. Judged from these relationships, Latin America may be home to at least a third of global biodiversity.

What are the current dimensions of biological diversity? Taxonomists have described approximately two million species of eukaryotic organisms. Many more remain unknown, and the global total may approximate 12 million species or more. Generally, for the past 65 million years, the rate of extinction of these species appears to have been ~0.1 extinctions per million species per year. Now, however, as a result of human activities, it has increased by about 1000 times, to ~100 species per million per year. We are losing species at about 1000 times the rate at which new ones are evolving. Many species are local and particularly liable to extinction, with climate change and increasing human-related pressures of all kinds pushing very strongly on life as it exists. Most of the species cannot be saved by forming parks and protected areas or away from their natural habitats unless human pressures are lessened by general action among nations, a prospect that is not being well realized at present. The strong call for the preservation of biodiversity in the encyclical Laudato Si’ represents the kind of ethical responsibility that must be adopted if there is to be any hope for the survival of our civilization.

Perhaps 12 million species of eukaryotic organisms share this planet with us, together with many more kinds of bacteria and their relatives. Most of these remain unknown to us. We depend completely on other organisms for the conditions that make possible our life on Earth and supply so many of our needs. However, our rapidly growing numbers and consumption patterns are so high that we are causing one of the most devastating extinction events that have ever occurred. We are clearly running a very dangerous experiment that we must strive to deflect both locally and globally before it becomes too late. Jammu and Kashmir, located in the northwestern Himalaya, is broadly defined as home to one of the richest and most diverse assemblies of biodiversity found in South Asia. An internationally based effort to save as much of these riches as possible, therefore, merits urgent research attention.

All Onagraceae for which data are available have vestured pits on vessel-to-vessel pit pairs. Vestures may also be present in some species on the vessel side of vessel-to-ray pit pairs. Herbaceous Onagraceae do not have fewer vestures, although woods with lower density (Circaea L. and Oenothera L.) have fewer vestures. Some Onagraceae from drier areas tend to have smaller vessel pits, and on that account may have fewer vestures (Epilobium L. and Megacorax S. Gonzalez & W. L. Wagner). Pit apertures as seen on the lumen side of vessel walls are elliptical, occasionally oval, throughout the family. Vestures are predominantly attached to pit aperture margins. As seen from the outer surfaces of vessels, vestures may extend across the pit cavities. Vestures are usually absent or smaller on the distal portions of pit borders (except for Ludwigia L., which grows consistently in wet areas). Distinctive vesture patterns were observed in the several species of Lopezia Cav. and in Xylonagra Donn. Sm. & Rose. Vestures spread onto the lumen-facing vessel walls of Ludwigia octovalvis (Jacq.) P. H. Raven. Although the genera are presented here in the sequence of a recent molecular phylogeny of Onagraceae, ecology and growth forms are more important than evolutionary relationships with respect to abundance, degree of grouping, and morphology of vestured pits. Designation of vesture types is not warranted based on the distribution of named types in Onagraceae and descriptive adjectives seem more useful, although more data on vesturing in the family are needed before patterns of diversity and their extent can be fully ascertained. Vestures are less common and may have a more complicated genetic basis than helical thickenings in vessels, but may be a more effective form of water column maintenance.

Como parte de una revisión integral de las especies nativas de los Valles Calchaquíes de Salta, Argentina, se presentan descripciones de Vachellia aroma, V. caven, y Parasenegalia visco, junto con una clave para las especies, comentarios sobre los usos de las mismas y una lista de especímenes representativos estudiados. En este trabajo se reconocen los géneros segregados de Acacia s.l., y son utilizados por primera vez para la Flora Argentina. As part of an integral review of the native species of the Calchaquí Valleys of Salta, Argentina, descriptions of Vachellia aroma, V. caven, and Parasenegalia visco are presented, along with a key for the species, comments about uses, and a list of representative specimens. In this study these genera segregated from Acacia s.l. are recognized and used for the first time for the Flora of Argentina.

Mainstream competitiveness and international development analyses pay little attention to the significance of a country&rsquo, s resource security for its economic performance. This paper challenges this neglect, examining the economic implications of countries resource dynamics, particularly for low-income countries. It explores typologies of resource patterns in the context of those countries&rsquo, economic prospects. To begin, the paper explains why it uses Ecological Footprint and biocapacity accounting for its analysis. Data used for the analysis stem from Global Footprint Network&rsquo, s 2018 edition of its National Footprint and Biocapacity Accounts. Ranging from 1961 to 2014, these accounts are computed from UN data sets. The accounts track, year by year, how much biologically productive space is occupied by people&rsquo, s consumption and compare this with how much productive space is available. Both demand and availability are expressed in productivity-adjusted hectares, called global hectares. Using this biophysical accounting perspective, the paper predicts countries&rsquo, future socio-economic performance. This analysis is then contrasted with a financial assessment of those countries. The juxtaposition reveals a paradox: Financial assessments seem to contradict assessments based on biophysical trends. The paper offers a way to reconcile this paradox, which also elevates the significance of biophysical country assessments for shaping successful economic policies.

We are destroying the life-support systems of Earth rapidly, making our future uncertain. Ecosystems—the complex sets of organisms that form the globe's living landscape—regulate the atmosphere, water, and soils. They supply humanity its food, most medicines, and many other essential products, and they fill our lives with beauty. But they are falling apart as, one by one, their constituent species are lost. To save what we can and provide our children and grandchildren with a sustainable future, studies must be conducted not only in nature but also, to an increasing extent, on the billions of specimens preserved in the world's natural history collections. For many species barely hanging on in their endangered habitats, these samples will one day be all that we have. Last week's United Nations Summit on Biodiversity discussed earlier reports that perhaps 1 million of the estimated 8.5 million species of plants, animals, and other organisms are in imminent danger of extinction. Probably as many as half of the populations of organisms that existed half a century ago are already gone. Over the past quarter century, about a quarter of all tropical forests have been lost. Because we have identified no more than a tenth of the estimated tens of thousands of species in those habitats, most that were lost may forever remain unknown. Unless we control the underlying causes, including overdevelopment and climate change, we are in danger of losing 80% or more of the world's species, the proportion lost 66 million years ago when the dinosaurs became extinct and many of the plants and animals known today began their ascent. We have clearly entered the world's sixth major extinction event. While we work to forestall this destruction, we must treat the specimens in our collections with ever more care. They are no longer simply samples of wild populations from which more will always be available. As many as half of the specimens likely represent populations that no longer exist, and an increasing number of species as well. What is in our collections will often turn out to be all that remains of organisms that once thrived. Faced with this grave future, we must find ways to preserve these specimens as well as we can for as long as we can. They are vulnerable to degradation and loss from pests, humidity, fire, and the simple ravages of time. While renewing efforts to protect them, we need to make them more accessible through digitization, including imaging and DNA barcoding (at least a minimal DNA sequence of the representative specimens). We also need to continue targeted sampling, focused on key taxa and habitats. Some groups of great ecological and environmental importance are dying off too rapidly to ever be completely understood. We have named 25,000 species of nematodes, 64,000 species of mites, and 100,000 species of fungi. Yet each of these groups is estimated to consist of a million or more species, with the number of fungi likely to be 2.2 to 2.6 million. We must sample them and understand them as well as we can before many of their species disappear forever. To do all of this, we need many more specialists in all regions of the world who are trained in advanced methods for collecting and preserving specimens, and in the exciting new field of “museomics”—determining DNA sequences from old preserved specimens. The standards for the best preservation and training established by the International Society for Biological and Environmental Repositories may help point the way. Many of the world's biological collections are in institutions that depend in part on attendance for their support. In this time of coronavirus disease 2019 (COVID-19), many of them will fail financially or be unable to continue maintaining their own collections. These and other potentially “orphan” collections have immense value and should be monitored and incorporated as needed into permanent homes. This is likely to be our last chance to know many of Earth's species. We must make the most of it.

This comment raises concerns regarding the way in which a new European directive, aimed at reaching higher renewable energy targets, treats wood harvested directly for bioenergy use as a carbon-free fuel. The result could consume quantities of wood equal to all Europe’s wood harvests, greatly increase carbon in the air for decades, and set a dangerous global example.

We’re being warned of future grain failures—not by the dreams of a biblical Pharaoh, but by modern computer model predictions. Climate science forecasts rising temperatures, changing rainfall patterns, and episodes of increasingly extreme weather, which will harm crop yields at a time when the world’s growing population can ill afford declines, especially in its most productive areas, such as the US Midwest. In order to adequately prepare, we call for the establishment of a new field research network across the US Midwest to fully integrate all methods for improving cropping systems and leveraging big data (agronomic, economic, environmental, and genomic) to facilitate adaptation and mitigation. Such a network, placed in one of the most important grain-producing areas in the world, would provide the set of experimental facilities, linked to farm settings, needed to explore and test the adaptation and mitigation strategies that already are needed globally.