Pollination is an important ecological process. However, the needs of plants and pollinators are not always met. Pollen limitation commonly reduces seed set and bees often experience nectar dearth. Using a theoretical cost-benefit optimization model we show that natural selection acting at the level of individual plants and pollinators will result in positive feedback that exacerbates pre-existing imbalances between nectar supply and demand. When pollinators are scarce plants will be selected to produce more nectar to outcompete other plants in attracting pollinators, and when pollinators are abundant plants will be selected to produce less nectar. We encourage the testing of this novel hypothesis and propose several ways of doing this via comparative study and experimental manipulation. We also suggest that evidence for seasonal variation in foraging conditions provides preliminary empirical support. If our hypothesis is correct it means that pollination faces a particular challenge in balancing nectar supply with demand.

Global change drivers alter multiple components of community composition, with cascading impacts on ecosystem stability. However, few studies have examined the complex interplay between global change drivers, synchrony, and diversity, especially over long-term successional dynamics. We analyzed a 22-year time series of grassland community data from Cedar Creek, USA, to examine the joint effects of pulse soil disturbance and press nitrogen addition on community synchrony, diversity, and stability during transient and post-transient periods of succession. Using multiple regression and structural equation modeling, we found that global change drivers decreased both synchrony and stability, thereby decoupling classic theoretical relationships, such as the portfolio effect. While the effect of soil disturbance weakened through time, nitrogen addition induced unexpected dynamics with maintained long-term impacts on composition, synchrony, and stability. Our findings underscore the need for long-term data and a comprehensive approach when managing ecosystems under ongoing global environmental changes.

Metabolism underpins all life-sustaining processes and varies profoundly with body size, temperature, and locomotor activity. A current theory explains some of the size-dependence of metabolic rate (its mass exponent, b) through changes in metabolic level (L). We propose two predictive advances that: (a) combine the above theory with the evolved avoidance of oxygen limitation in water-breathers experiencing warming, and (b) quantify the overall magnitude of combined temperatures and degrees of locomotion on metabolic scaling across air- and water-breathers. We use intraspecific metabolic scaling responses to temperature (523 regressions) and activity (281 regressions) in diverse ectothermic vertebrates (fish, reptiles and amphibians) to show that b decreases with temperature-increased L in water-breathers, supporting surface area-related avoidance of oxygen limitation, whereas b increases with activity-increased L in air-breathers, following volume-related influences. This new theoretical integration quantitatively incorporates different influences (warming, locomotion) and respiration modes (aquatic, terrestrial) on animal energetics.

Animal migration impacts organismal health and disease transmission: migrants are simultaneously exposed to parasites and able to reduce infection at the population and individual levels. However, these dynamics are difficult to study; empirical studies reveal disparate results while existing theory makes assumptions that simplify natural complexity. Here, we systematically review empirical studies of migration and infection across taxa, highlighting key gaps in our understanding. Next, we develop a unified evolutionary framework incorporating different mechanisms of parasite-migration interactions while accounting for ecological complexity that goes beyond previous theory. Our framework generates diverse migration-infection patterns paralleling those seen in empirical systems, including partial and differential migration. Finally, we generate predictions about which mechanisms dominate which empirical systems to guide future studies. Our framework provides an overarching understanding of selective pressures shaping migration patterns in the context of animal health and disease, which is critical for predicting how environmental change may threaten migration.

Most animals undergo ontogenetic niche shifts during their life. Yet, standard ecological theory builds on models that ignore this complexity. Here, we study how complex life cycles, where juvenile and adult individuals each feed on different sets of resources, affect community richness. Two different modes of community assembly are considered: gradual adaptive evolution and immigration of new species with randomly selected phenotypes. We find that under gradual evolution complex life cycles can lead to both higher and lower species richness when compared to a model of species with simple life cycles that lack an ontogenetic niche shift. Thus, complex life cycles do not per se increase the scope for gradual adaptive diversification. However, complex life cycles can lead to significantly higher species richness when communities are assembled trough immigration, as immigrants can occupy isolated peaks of the dynamic fitness landscape that are not accessible via gradual evolution.

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.

A document by Julian Lilkendey. Click on the document to view its contents.

Forest soil CO2 efflux (FCO2) is a crucial process in global carbon cycling; however, how FCO2 respond to disturbance regimes in different forest biomes is poorly understood. We quantified the effects of disturbance regimes on FCO2 across boreal, temperate, tropical, and Mediterranean forests based on 1240 observations from 380 studies. Globally, FCO2 was increased by 13 to 25% due to climatic perturbations such as elevated CO2 concentration, warming, and increased precipitation. FCO2 was increased by forest conversion to grassland and elevated carbon input by forest management practices but was reduced by decreased carbon input, fire, and acid rain. Disturbance also caused changes in soil temperature and water content, which in turn affected the direction and magnitude of disturbance effects on FCO2. Our results suggest that disturbance effects on FCO2 should be incorporated into earth system models to improve the projection of feedback between the terrestrial C cycle and climate change.

Seed dispersal directly affects plant establishment, gene flow, and fitness. As a result, understanding patterns in seed dispersal is fundamental to understanding plant ecology and evolution, as well as addressing challenges of extinction and global change. Our ability to understand dispersal is limited because few frameworks have emerged that provide a means for predicting dispersal across time and space. We provide a novel framework that links seed dispersal to animal social status, a key component of behavior. Because social status affects individual resource access and movement, it provides a critical link to two factors that determine seed dispersal: the quantity of seeds dispersed and the spatial patterns of dispersal. Moreover, individual social status may have unappreciated effects on post-dispersal seed survival and recruitment when social status affects individual habitat use. Hence, environmental changes, such as selective harvesting and urbanization, that affect animal social structure may have unappreciated consequences for seed dispersal. The framework we present highlights these exciting new hypotheses linking environmental change, social structure, and seed dispersal. By outlining experimental approaches to test these hypotheses, we hope to facilitate studies across a wide diversity of plant-frugivore networks, which may uncover emerging hotspots or catastrophic losses of seed dispersal.

Foraging by consumers acts as a biotic filtering mechanism for biodiversity at the trophic level of resources. Variation in foraging behaviour have cascading effects on abundance, diversity, and functional trait composition of the community of resource species. Here we propose diversity at giving-up density (DivGUD), when foragers quit exploring a patch, as a novel concept and simple measure to quantify these effects at multiple spatial scales. In experimental landscapes, patch residency of wild rodents decreased local α-DivGUD (via elevated mortality of species with large seeds) and regional γ-DivGUD, while dissimilarity among patches in a landscape (ß-DivGUD) increased. Thus, DivGUD provides a framework linking theories of adaptive foraging behaviour with community ecology allowing to investigate cascading indirect predation effects across multiple trophic levels e.g. the ecology-of-fear framework; feedbacks between functional trait composition of resource species and consumer communities; and effects of inter-individual differences among foragers on the biodiversity of resource communities.

Almost 50 years ago, Michael Rosenzweig pointed out that nutrient addition can destabilize food webs, leading to loss of species and reduced ecosystem function through the paradox of enrichment. Around the same time, David Tilman demonstrated that increased nutrient loading would also be expected to cause competitive exclusion leading to deleterious changes in food web diversity. While both concepts have greatly illuminated general diversity-stability theory, we currently lack a coherent framework to predict how nutrients influence food web stability across a landscape. This is a vitally important gap in our understanding, given mounting evidence of serious ecological disruption arising from anthropogenic displacement of resources and organisms. Here, we combine contemporary theory on food webs and meta-ecosystems to show that nutrient additions are indeed expected to drive loss in stability and function in human-impacted regions. However, this loss in stability occurs not just from wild oscillations in population abundance, but more frequently from the complete loss of an equilibrium due to edible plant species being competitively excluded. In highly modified landscapes, spatial nutrient transport theory suggests that such instabilities can be amplified over vast distances from the sites of nutrient addition. Consistent with this theoretical synthesis, the empirical frequency of these distant propagating ecosystem imbalances appears to be growing. This synthesis of theory and empirical data suggests that human modification of the Earth’s ecological connectivity is “entangling” once distantly separated ecosystems, causing rapid, expansive, and costly nutrient-driven instabilities over vast areas of the planet. The corollary to this spatial nutrient theory, though – akin to weak interaction theory from food web networks – is that slow spatial nutrient pathways can be potent stabilizers by moderating flows across a landscape

Harvesting can magnify the destabilizing effects of environmental perturbations on population dynamics and, thereby, increase extinction risk. However, population-dynamic theory predicts that impacts of harvesting depend on the type and strength of density-dependent regulation. Here, we used logistic population growth models and an empirical reindeer case study to show that low to moderate harvesting can actually buffer populations against environmental perturbations. This occurs because of density-dependent environmental stochasticity, where negative environmental impacts on vital rates are amplified at high population density due to intraspecific resource competition. Simulations from our population models show that even low levels of harvesting may prevent overabundance, thereby dampening population fluctuations and reducing the risk of population collapse and quasi-extinction following environmental perturbations. Thus, depending on the species' life history and the strength of density-dependent environmental drivers, low to moderate harvesting can improve population resistance to increased climate variability and extreme weather expected under global warming.

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.

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.

Heterogeneity among individuals in fitness components is what selection acts upon. Evolutionary theories predict that selection in constant environments acts against such heterogeneity. But observations reveal substantial non-genetic and also non-environmental variability in phenotypes. Here we examine whether there is a relationship between selection pressure and phenotypic variability by analysing structured population models based on data from a large and diverse set of species. Our findings suggest that non-genetic, non-environmental variation is in general neither truly neutral, selected for, or selected against. We find much variation among species and populations within species, with mean patterns suggesting nearly neutral evolution of life course variability. Populations that show greater diversity of life courses do not show, in general, increased or decreased population growth rates. Our analysis suggests we are only at the beginning in understanding the evolution and maintenance of non-genetic non environmental variation.

Taxonomic diversity effects on forest productivity and response to climate extremes range from positive to negative, suggesting a key role for complex interactions among neighbouring trees. To elucidate how neutral interactions, hierarchical competition and resource partitioning between neighbours shape tree growth and climate response in a highly diverse Amazonian forest, we combined 30 years of tree censuses with measurements of water and carbon related traits. We modelled individual tree growth response to climate and neighbourhood to disentangle the relative effect of neighbourhood densities, trait hierarchies and dissimilarities. While neighbourhood densities consistently decreased tree growth, trait dissimilarity increased it, and both influenced climate response. Greater water conservatism provided a competitive advantage to focal trees in normal years, but water spender neighbours reduced this effect in dry years. By highlighting the importance of density and trait-mediated neighbourhood interactions, our study offers a way towards improving predictions of forest response to climate change.

Local minority languages and dialects, through the local knowledge and expertise associated with them, can play major roles in analyzing climate change and biodiversity loss, in facilitating community awareness of environmental crises and in setting up locally-adapted resilience and sustainability strategies. While the situation and contribution of deeply-rooted Indigenous Peoples are of emblematic importance, the issue of the relationships between cultural and linguistic diversity and environmental awareness and protection does not solely concern peripheral highly-specialized communities in specific ecosystems of the Global South, but constitutes a worldwide challenge, throughout all of the countries, whatever their geographical location, their economical development, or their political status. Environmental emergency and climate change resilience should therefore raise international awareness on the need to promote the survival and development of minority languages and dialects and to take into account their creativity and expertise in relation with the dynamics of their local environments.

Wintering birds serve as vital climate sentinels, yet they are often underrepresented in comprehensive surveys and overlooked in studies of avian diversity change. Here, we provide a continental-scale characterization of change in multiple facets of wintering avifauna and examine the effects of climate change on these dynamics. We reveal a strong functional reorganization of wintering bird communities marked by a distinct east-west gradient in functional diversity change, along with a superimposed north-south gradient in trait composition change. Assemblages in the eastern US saw an expansion of the functional space and increases in functional originality, evenness, and divergence, while the western US saw contractions of the functional space. Shifts in functional diversity were underlined by significant reshuffling in trait composition, particularly pronounced in the northern US. Finally, we find strong contributions of climate change to this functional reorganization, underscoring the importance of wintering birds in tracking climate change impacts on biodiversity.