Ecology of a widespread large omnivore, Homo sapiens, and its impacts on ecosystem processes

Diversity-dependent speciation and extinction in hominins

The search for drivers of hominin speciation and extinction has tended to focus on the impact of climate change. Far less attention has been paid to the role of interspecific competition. However, research across vertebrates more broadly has shown that both processes are often correlated with species diversity, suggesting an important role for interspecific competition. Here we ask whether hominin speciation and extinction conform to the expected patterns of negative and positive diversity dependence, respectively. We estimate speciation and extinction rates from fossil occurrence data with preservation variability priors in a validated Bayesian framework and test whether these rates are correlated with species diversity. We supplement these analyses with calculations of speciation rate across a phylogeny, again testing whether these are correlated with diversity. Our results are consistent with clade-wide diversity limits that governed speciation in hominins overall but that were not quite reached by the Australopithecus and Paranthropus subclade before its extinction. Extinction was not correlated with species diversity within the Australopithecus and Paranthropus subclade or within hominins overall; this is concordant with climate playing a greater part in hominin extinction than speciation. By contrast, Homo is characterized by positively diversity-dependent speciation and negatively diversity-dependent extinction-both exceedingly rare patterns across all forms of life. The genus Homo expands the set of reported associations between diversity and macroevolution in vertebrates, underscoring that the relationship between diversity and macroevolution is complex. These results indicate an important, previously underappreciated and comparatively unusual role of biotic interactions in Homo macroevolution, and speciation in particular. The unusual and unexpected patterns of diversity dependence in Homo speciation and extinction may be a consequence of repeated Homo range expansions driven by interspecific competition and made possible by recurrent innovations in ecological strategies. Exploring how hominin macroevolution fits into the general vertebrate macroevolutionary landscape has the potential to offer new perspectives on longstanding questions in vertebrate evolution and shed new light on evolutionary processes within our own lineage.

The human side of biodiversity: coevolution of the human niche, palaeo-synanthropy and ecosystem complexity in the deep human past

Today's biodiversity crisis fundamentally threatens the habitability of the planet, thus ranking among the primary human challenges of our time. Much emphasis is currently placed on the loss of biodiversity in the Anthropocene, yet these debates often portray biodiversity as a purely natural phenomenon without much consideration of its human dimensions and frequently lack long-term vistas. This paper offers a deep-time perspective on the key role of the evolving human niche in ecosystem functioning and biodiversity dynamics. We summarize research on past hunter-gatherer ecosystem contributions and argue that human-environment feedback systems with important biodiversity consequences are probably a recurrent feature of the Late Pleistocene, perhaps with even deeper roots. We update current understandings of the human niche in this light and suggest that the formation of palaeo-synanthropic niches in other animals proffers a powerful model system to investigate recursive interactions of foragers and ecosystems. Archaeology holds important knowledge here and shows that ecosystem contributions vary greatly in relation to different human lifeways, some of which are lost today. We therefore recommend paying more attention to the intricate relationship between biodiversity and cultural diversity, contending that promotion of the former depends on fostering the latter. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

An interdisciplinary course on evolution and sustainability increases acceptance of evolutionary theory and increases understanding of interdisciplinary application of evolutionary theory

Background

Although evolutionary theory is foundational and integrative in modern biology, there remains widespread lack of acceptance among U.S. residents. An interdisciplinary approach to teaching evolutionary theory at the undergraduate level has many advantages, such as giving students a context for learning about evolution and application of evolutionary theory to other academic disciplines and everyday life. While there are foundational examples of interdisciplinary approaches to teaching evolutionary theory, there are few examples of courses with application of evolutionary theory to issues of sustainability, such as conservation or global climate change. We build on the practical and theoretical work of others to create an interdisciplinary course on evolutionary theory for non-science majors, with ties to sustainability. Our course is taught in three modules, with extensive readings and hands-on lab activities. The first module is focused on honey bee biology, with hands-on beekeeping experiences; the second module on native plants and community education on sustainability; and the third module on the evolution of the subjective human experience of free will.

Results

We found that students in our course experienced an increased acceptance of evolutionary theory. We found that students also met the course leaning objectives, of basic knowledge of evolutionary theory and application of evolutionary theory to other disciplines, assessed through group and individual major assignments. We also found that students had an expanded perspective on interdisciplinary application of evolutionary theory, assessed through closed-ended survey questions and analysis of open-ended writing.

Conclusions

Students in our course experienced an increase of acceptance of evolutionary theory and an expanded perspective on interdisciplinary application of evolutionary theory, despite the fact that many students were not science majors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12052-023-00188-4.

Reciprocal Contributions between People and Nature: A Conceptual Intervention

Throughout human history, Indigenous and local communities have stewarded nature. In the present article, we revisit the ancestral principle of reciprocity between people and nature and consider it as a conceptual intervention to the current notion of ecosystem services commonly used to inform sustainability transformation. We propose the concept of reciprocal contributions to encompass actions, interactions, and experiences between people and other components of nature that result in positive contributions and feedback loops that accrue to both, directly or indirectly, across different dimensions and levels. We identify reciprocal contributions and showcase examples that denote the importance of reciprocity for our ecological legacy and its relevance for biocultural continuity. We suggest that the concept of reciprocal contribution can support transformation pathways by resituating people as active components of nature and restructuring institutions so that ethical principles and practices from Indigenous and local communities can redirect policy approaches and interventions worldwide.

Mammalian Mycophagy: a Global Review of Ecosystem Interactions Between Mammals and Fungi

The consumption of fungi by animals is a significant trophic interaction in most terrestrial ecosystems, yet the role mammals play in these associations has been incompletely studied. In this review, we compile 1 154 references published over the last 146 years and provide the first comprehensive global review of mammal species known to eat fungi (508 species in 15 orders). We review experimental studies that found viable fungal inoculum in the scats of at least 40 mammal species, including spores from at least 58 mycorrhizal fungal species that remained viable after ingestion by mammals. We provide a summary of mammal behaviours relating to the consumption of fungi, the nutritional importance of fungi for mammals, and the role of mammals in fungal spore dispersal. We also provide evidence to suggest that the morphological evolution of sequestrate fungal sporocarps (fruiting bodies) has likely been driven in part by the dispersal advantages provided by mammals. Finally, we demonstrate how these interconnected associations are widespread globally and have far-reaching ecological implications for mammals, fungi and associated plants in most terrestrial ecosystems.

The policy consequences of defining rewilding

More than 30 years after it was first proposed as a biodiversity conservation strategy, rewilding remains a controversial concept. There is currently little agreement about what the goals of rewilding are, and how these are best achieved, limiting the utility of rewilding in mainstream conservation. Achieving consensus about rewilding requires agreeing about what "wild" means, but many different definitions exist, reflecting the diversity of values in conservation. There are three key debates that must be addressed to find a consensual definition of "wild": (1) to which extent can people and "wild" nature co-exist?; (2) how much space does "wild" nature need? and (3) what kinds of "wild" nature do we value? Depending on the kinds of "wild" nature rewilding aims to create, rewilding policy will be faced with managing different opportunities and risks for biodiversity and people.