Peter H. Raven’s research while affiliated with Missouri Botanical Garden and other places

At the XIX International Botanical Congress held in Shenzhen, China, in July 2017, the delegates unanimously adopted the Shenzhen Declaration on Plant Sciences in an effort to accelerate the contributions made by plant scientists for the benefit of the world′s changing society. This paper discusses what has been accomplished concerning plant conservation since the Shenzhen Declaration. Beyond the problems we faced in 2017, the global Covid pandemic and the war have presented new challenges. With the massive ecological overshoot, the number of malnourished people globally has increased. Most threats to vascular plants have increased generally over these 6 years, while the responses of the botanical community to them have continued to proceed at a relatively slow pace. Although international cooperation is needed to combat the grave challenges we face, the ease of such collaboration has decreased substantially in recent years. Certainly, rapid deforestation, especially in the tropics, and our ineffective approaches to mitigate climate change will lessen the effectiveness of our strategies to slow extinction. Indeed, our blindness to the reality of ecological overshoot and misperceptions concerning sustainability are accelerating extinction and thus destabilizing social structures and civilization. As an example, conservation in China faces serious challenges with biodiversity loss, but botanical gardens and seed banks there offer hope on ex situ conservation. The botanical and other scientific communities can contribute by drawing the attention of fellow citizens to the gravity of the problems that we face and by being actively engaged in providing solutions and carrying them forward to action.

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.

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’.

In their comment on our paper “Underestimating the challenges of avoiding a ghastly future” (Bradshaw et al., 2021), Bluwstein et al. (2021) attempt to contravene our exposé of the enormous challenges facing the entire human population from a rapidly degrading global environment. While we broadly agree with the need for multi-disciplinary solutions, and we worry deeply about the inequality of those who pay the costs of biodiversity loss and ecological collapse, we feel obligated to correct misconceptions and incorrect statements that Bluwstein et al. (2021) made about our original article.

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’.

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.