Banks-Leite et al. (2021) claim that our suggestion of preserving ≥40% forest cover lacks evidence and can be problematic. We find these claims unfounded, and discuss why conservation planning urgently requires valuable, well-supported, and feasible general guidelines like the 40% criterion. Using region-specific thresholds worldwide is unfeasible and potentially harmful.
Vector-borne diseases (VBDs) are embedded within complex socio-ecological systems. While research has traditionally focused on direct effects of VBDs on morbidity and mortality, it is increasingly clear that VBD impacts are much more pervasive, dynamically linked to feedbacks between environmental conditions, vector ecology, disease burden, and societal responses that drive transmission. VBDs have had profound influence on human history via mechanisms that include: (1) killing or debilitating large numbers of people, with direct demographic and population-level impacts; (2) differentially affecting populations based on prior history of disease exposure, immunity, and resistance; (3) being weaponized to promote or justify existing hierarchies of power, colonialism, racism, classism, and sexism; (4) catalyzing changes in ideas, institutions, infrastructure, technologies, and social practices in efforts to control disease outbreaks; and (5) changing human relationships with the land and environment. We use historical and archaeological evidence interpreted through an ecological lens to illustrate how four major VBDs have shaped society and culture: plague, malaria, yellow fever, and trypanosomiasis. By comparing across diseases, time periods, and geographies, this review highlights the enormous scope and variety of mechanisms by which VBDs have influenced human history from the age of early Homo sapiens to the modern context.
A recent review on optimal strategies for preserving biodiversity within human-modified landscapes suggests that that forest cover needs to be restored or maintained to at least 40%. While we agree that it is paramount to protect and increase cover in forested biomes, no evidence is presented to support this 40% threshold. Furthermore, there are several issues regarding implementation of such policy or social-economic constraints that makes this suggestion unhelpful and potentially dangerous.
Size and shape profoundly influence an organism’s ecophysiological performance and evolutionary fitness, suggesting a link between morphology and diversity. However, not much is known about how body shape is related to taxonomic richness, in particular in the microbial realm. Here we analyse global datasets of unicellular phytoplankton, a major photosynthetic group with an exceptional diversity of cell sizes and shapes. Using two measures of cell shape elongation, we quantify taxonomic diversity as a function of cell size and shape. We find that cells of intermediate volume have the greatest shape variation, from oblate to extremely elongated forms, while small and large cells are mostly compact (e.g., spherical or cubic). Taxonomic diversity is strongly related with cell elongation and cell volume, with both traits, in combination, explaining up to 92% of total variance. Diversity decays exponentially with cell elongation and displays a log-normal dependence on cell volume, peaking for compact, intermediate-volume cells. These previously unreported broad patterns in phytoplankton diversity reveal selective pressures and ecophysiological constraints on the geometry of phytoplankton cells which may improve our understanding of marine ecology and the evolutionary rules of life.
In ectothermic predator-prey relationships, the capacity for prey to successfully evade predation will depend upon physiological and behavioural responses that relate to both players’ thermal biology. On the Izu Islands of Japan, we investigated how a prey lizard species has responded physiologically and thermally to the presence of a snake predator over evolutionary time in addition to recent climatic warming. Foraging lizard body temperatures have increased by 1.0°C from 1981 to 2019 while lizard body temperatures were 3.4°C warmer on islands where the snake predator is present relative to snake-free islands. We also found that warmer prey body temperatures result in faster running speeds of the prey at temperatures suboptimal for the snake predator. The results show that lizard body temperatures have increased with warming but not to the same extent as that exerted by predation pressure. However, further warming could irrevocably alter this and other ectothermic predator-prey relationships.
Forecasts of forest responses to climate variability are governed by climate exposure and ecosystem sensitivity, but ecosystem model projections and process representations are under-constrained by data at multidecadal and longer timescales. Here, we assess ecosystem sensitivity to centennial-scale hydroclimate variability, by comparing dendroclimatic and pollen-inferred reconstructions of drought, forest composition and biomass for the last millennium with five ecosystem model simulations. In both observations and models, spatial patterns in ecosystem responses to hydroclimate variability are strongly governed by ecosystem sensitivity rather than climate exposure. Ecosystem sensitivity was highest in simpler models and higher than observations, suggesting that interactions among biodiversity, demography, and ecophysiology processes dampen the sensitivity of forest composition and biomass to climate variability and change. By integrating ecosystem models with observations from timescales extending beyond the instrumental record, we can better understand and forecast the mechanisms regulating forest sensitivity to climate variability in a complex and changing world.
The recent upsurge in the edible insect market has seen industrialisation and intensification without adequate regulatory policy guidelines in place. The species being reared and sold are often non-native, in rearing centres not equipped to contain the species, and in areas without regional or national pre-entry regulations, post-entry monitoring guidelines and early response programs to address escapee species. Such unregulated transport, trade and rearing of species, compounded by the policy and implementation loopholes at the regional, national and international levels will most likely lead to new biological invasions, as has been witnessed with other unregulated trade practices. To avoid this, it is necessary to monitor and regulate the species to be reared, to improve the quarantine guidelines of the rearing centres, and to be more stringent about the policies and practices that allow movements of non-native species across international borders.
Despite widespread evidence that biological invasion influences both the biotic and abiotic soil environments, the extent to which these two pathways underpin the effects of invasion on plant traits and performance is unknown. Leveraging a long-term (14-yr) field experiment, we show that an allelochemical-producing invader affects plants through biotic mechanisms, altering the soil fungal community composition, with no apparent shifts in soil nutrient availability. Changes in belowground fungal communities result in high costs of nutrient uptake for native perennials and a shift in functional traits linked to their water and nutrient use efficiencies. Some species in the invaded community compensate for high nutrient costs by reducing nutrient uptake and maintaining photosynthesis by expending more water, which demonstrates a trade-off in trait investment. For the first time, we show that the disruption of belowground nutritional symbionts can drive native plants toward novel regions in order to maintain their water and nutrient economics.
Changing environments and habitat structure likely affect eco-evolutionary processes involved in the spatial spread of disease. Exploitative parasites are predicted to evolve in highly connected populations or in expanding epidemics. However, many parasites rely on host dispersal to reach new populations, potentially causing conflict between local transmission and global spread. We performed experimental range expansions in interconnected microcosms of the protozoan Paramecium caudatum, allowing natural dispersal of hosts infected with the bacterial parasite Holospora undulata. Parasites from range front treatments were less virulent and interfered less with host dispersal, but also invested less in horizontal transmission than parasites from range cores. An epidemiological model fitted on experimental time-series data confirmed this trade-off between dispersal adaptation and transmission, so far rarely considered in theoretical models. Our study illustrates the importance of the ecology and evolution of dispersal-related traits in spatial non-equilibrium scenarios, including emerging diseases, metapopulations or biological invasions.
Natural systems are always fluctuating: no two years are identical, with population and community sizes varying from one year to the next. Such variation has led to “equilibrium” becoming almost a dirty word in ecology. Some researchers see the world as being in permanent flux, and consider our field’s historical focus on equilibria as out-dated. But this view is flawed, is driven by current day observations of a world out of kilter, and risks downplaying the risks of ongoing anthropogenic change to civilisation and perhaps too to life on Earth. In this viewpoint, I mount a defence for equilibria.
The frequency distribution of individual body sizes in animal communities (i.e. the size spectrum) provides powerful insights for understanding the energy flux through food webs. However, studies of size spectra in rocky and coral reef communities typically focus only on fishes or invertebrates due to taxonomic and data constraints, and consequently ignore energy pathways involving the full range of macroscopic consumer taxa. We analyse size spectra with co-located fish and mobile macroinvertebrate data from 3,391 reef sites worldwide, specifically focusing on how the addition of invertebrate data alters patterns. The inclusion of invertebrates steepens the size spectrum, more so in temperate regions, resulting in a consistent size spectrum slope across latitudes, and bringing slopes close to theoretical expectations based on energy flow through the system. These results highlight the importance of understanding contributions of both invertebrates and fishes to reef food webs worldwide.
Soil ecological stoichiometry provides powerful theories to integrate the complex interplay of element cycling and microbial communities into biogeochemical models. One essential assumption is that microbes maintain stable C:N:P (carbon:nitrogen:phosphorus) ratios independent of resource supply, although such homeostatic regulations have rarely been assessed in individual microorganisms. Here, we report an unexpected high flexibility in C:N and C:P values of saprobic fungi along nutrient supply gradients, overall ranging between 7-126 and 20-1488, respectively, questioning microbial homeostasis. Fungal N:P varied comparatively less due to simultaneous reductions in mycelial N and P contents. As a mechanism, internal recycling processes during mycelial growth and an overall reduced N and P uptake appear more relevant than element storage. The relationships among fungal stoichiometry and growth disappeared in more complex media. These findings affect our interpretation of stoichiometric imbalances among microbes and soils and are highly relevant for developing microbial soil organic carbon and nitrogen models.
Ant Forest, a mobile app by the monolithic Alibaba Group, is greening individuals' daily activities and transforming human capacity to reverse global environmental degradation. Over 500 million e-trees being cultivated every day in China using Ant Forest. Over 122 million trees planted over more than 112,000 ha of degraded land areas. This is a showcase of how innovation via internet technology combined with digital finance is contributing to solving environmental issues, also the potential to match an individual's daily footprint to their digital footprint and converting this to an ecological footprint.
Non-consumptive predator effects (NCEs) are now widely recognized for their capacity to shape ecosystem structure and function. Yet, forecasting the propagation of these predator-induced trait changes through particular communities remains a challenge, in part because we lack a predictive framework that accounts for environmental and species context. Accordingly, focusing on plasticity in prey anti-predator behaviors, we conceptualize the multi-stage process by which predators trigger direct and indirect NCEs, review and then distill potential drivers of NCE contingencies into three key categories (properties of the prey, predator, and setting), and conduct a meta-analysis to quantify the extent to which prey behavioral plasticity in response to predation risk hinges on a well-studied driver – prey energetic state. Our synthesis underscores the myriad factors that can generate NCE contingencies while guiding how research might better anticipate and account for them. We highlight two key knowledge gaps that continue to hinder development of a comprehensive framework for exploring non-consumptive predator-prey interactions. These are insufficient exploration of 1) context-dependent indirect NCEs and 2) the ways in which direct and indirect NCEs are shaped interactively by multiple drivers of context dependence.
Ecological research is highlighting different kinds of issues concerning biodiversity conservation policies. Based on a historical study on protected areas, we suggest that these issues are not caused by a lack of knowledge or technical tools but rather by a misuse of ecological knowledge during the implementation of policy instruments. We strongly believe that determining the conditions under which ecological science can enlighten policy decisions is now necessary to address current biodiversity conservation issues. This can only be achieved through the promotion of interdisciplinary research.
The comment by Sánchez-Tójar et al. (2020, Ecol Lett) questioned the methodology, transparency, and conclusion of our study (Yin et al. 2019, Ecol Lett, 22, 1976). The comment has overlooked important evolutionary assumptions in their reanalysis, and the issues raised were in fact dealt with through the peer-review process. Far from being biased, the key conclusion of our meta-analysis still stands; transgenerational effects are largely adaptive.
Light asymmetry, with a higher light acquisition per unit biomass for larger plants, has been proposed as a major mechanism of species loss after nitrogen addition. However, solid evidence for this has been scarce. We measured the allometric size-height relationships of 25 plant species along a nitrogen addition gradient manipulated annually for eight years in a speciose alpine meadow and found that the rare species advantage of light acquisition (i.e., low height scaling exponent) in natural conditions disappeared after nitrogen addition. Those species failing to lower their height scaling exponents decreased in relative abundance after nitrogen addition, thereby decreasing the community weighted mean and dispersion of the height scaling exponent and ultimately the species richness. Our results provided some unique evidence for light asymmetry induced species loss after nitrogen addition and a new insight from the perspective of allometric growth to explain biodiversity maintenance in the face of global changes.
Rapid evolution of traits and of plasticity may enable adaptation to climate change, yet solid experimental evidence under natural conditions is scarce. Here, we imposed rainfall manipulations (+30%, control, -30%) for ten years on entire natural plant communities in two Eastern Mediterranean sites. Additional sites along a natural rainfall gradient and selection analyses in a greenhouse assessed whether potential responses were adaptive. In both sites, our annual target species Biscutella didyma consistently evolved earlier phenology and higher reproductive allocation under drought. Multiple arguments suggest that this response was adaptive: it aligned with theory, corresponding trait shifts along the natural rainfall gradient, and selection analyses under differential watering in the greenhouse. However, another seven candidate traits did not evolve, and there was little support for evolution of plasticity. Our results provide compelling evidence for rapid adaptive evolution under climate change. Yet, several non-evolving traits may indicate potential constraints to full adaptation.