Phylogenetic diversity promotes ecosystem stability

Ecosystem stability in variable environments depends on the diversity of form and function of the constituent species. Species phenotypes and ecologies are the product of evolution, and the evolutionary history represented by co-occurring species has been shown to be an important predictor of ecosystem function. If phylogenetic distance is a surrogate for ecological differences, then greater evolutionary diversity should buffer ecosystems against environmental variation and result in greater ecosystem stability. We calculated both abundance-weighted and unweighted phylogenetic measures of plant community diversity for a long-term biodiversity–ecosystem function experiment at Cedar Creek, Minnesota, USA. We calculated a detrended measure of stability in aboveground biomass production in experimental plots and showed that phylogenetic relatedness explained variation in stability. Our results indicate that communities where species are evenly and distantly related to one another are more stable compared to communities where phylogenetic relationships are more clumped. This result could be explained by a phylogenetic sampling effect, where some lineages show greater stability in productivity compared to other lineages, and greater evolutionary distances reduce the chance of sampling only unstable groups. However, we failed to find evidence for similar stabilities among closely related species. Alternatively, we found evidence that plot biomass variance declined with increasing phylogenetic distances, and greater evolutionary distances may represent species that are ecologically different (phylogenetic complementarity). Accounting for evolutionary relationships can reveal how diversity in form and function may affect stability

Recasting spatial food web ecology as an ecosystem science

Background/questions/methods

Food webs are complex systems in which organisms interact with each other and with the abiotic aspects of their environment, thus acting as the conduit for transfers of energy and nutrients through ecosystems. Classical approaches to food webs focus strongly on patterns and processes occurring at the community level rather than at the broader ecosystem scale. Recent developments in community ecology suggest that spatial processes may be important in affecting food web dynamics and affect ecosystems as well, thus leading to the idea of meta-ecosystems. Here, we make a synthesis on how the links between food web dynamics and spatial ecosystem dynamics may be studied through (i) identifying differences between metacommunity and landscape ecology approaches when dealing with food webs, (ii) arguing that a tighter synthesis of the two approaches is needed for a good understanding of how diversity, ecosystem process and trait distributions in landscapes are related, and (iii) laying out how this gap can be efficiently bridged under the framework of meta-ecosystems.

Results/conclusions

We identify two possible sets of processes that drive spatial food webs and the ecosystems they occur in: trait-dependent processes and material-dependent processes. Both of these have been shown to be important in affecting various aspects of food web ecology and we ask how they may compare to each other and how they may interact. We argue that interactions between them, while complex, are likely and depend strongly on the size of the meta-ecosystem and its connectivity. A more integrative framework to the study of spatial food webs, which takes into account both approaches, might be key in better understanding the links between ecosystem and community dynamics at large spatial scales.
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Nature-based Solutions and the Built Environment

1. KEY POINTS 1. The novelty of nature-based solutions (NbS) for cities lies in a focus on the cost-effective provision of multiple co-benefits for many urban residents. 2. A participatory placemaking approach to equitable co-design, co-creation and co-management of NbS that include multiple stakeholders and beneficiaries has the potential to maintain or improve biodiversity while simultaneously addressing societal issues such as climate change and other socio environmental inequalities across both spatial and temporal scales. 3. NbS harnesses blue and green infrastructure, such as sustainable drainage systems (SuDS), green roofs, rivers, urban trees and community green spaces, which support significantly higher levels of biodiversity than constructed ‘grey’ infrastructure. These features can also help urban areas adapt to increased and more extreme temperature and rainfall events associated with climate change whilst delivering important environmental, social and economic benefits. 4. Due to the multidisciplinary nature of NbS, its implementation in cities is inherently complex and at odds with many siloed governance structures, largely due to knowledge and skills gaps and the lack of coordination across sectors or departments, particularly at local authority level

Reply to: “Global Conservation of Phylogenetic Diversity Captures More Than Just Functional Diversity”

Academic biologists have long advocated for conserving phylogenetic diversity (PD), often (but not exclusively) on the basis that PD is a useful proxy for “feature diversity”, defined as the variety of forms and functions represented in set of organisms (see below for an extended discussion of this definition). In a recent paper, we assess the extent to which this proxy (which we coined the “phylogenetic gambit”) holds in three empirical datasets (terrestrial mammals, birds, and tropical marine fishes) when using functional traits and functional diversity (FD) to operationalize feature diversity. Owen et al. offer a criticism of our methods for quantifying feature diversity with FD and disagree with our conclusions. We are grateful that Owen et al. have engaged thoughtfully with our work, but we believe there are more points of agreement than Owen et al. imply

Prioritizing Phylogenetic Diversity Captures Functional Diversity Unreliably

In the face of the biodiversity crisis, it is argued that we should prioritize species in order to capture high functional diversity (FD). Because species traits often reflect shared evolutionary history, many researchers have assumed that maximizing phylogenetic diversity (PD) should indirectly capture FD, a hypothesis that we name the “phylogenetic gambit”. Here, we empirically test this gambit using data on ecologically relevant traits from \u3e15,000 vertebrate species. Specifically, we estimate a measure of surrogacy of PD for FD. We find that maximizing PD results in an average gain of 18% of FD relative to random choice. However, this average gain obscures the fact that in over one-third of the comparisons, maximum PD sets contain less FD than randomly chosen sets of species. These results suggest that, while maximizing PD protection can help to protect FD, it represents a risky conservation strategy

On the Relationship Between Phylogenetic Diversity and Trait Diversity

Niche differences are key to understanding the distribution and structure of biodiversity. To examine niche differences, we must first characterize how species occupy niche space, and two approaches are commonly used in the ecological literature. The first uses species traits to estimate multivariate trait space (so‐called functional trait diversity, FD); the second quantifies the amount of time or evolutionary history captured by a group of species (phylogenetic diversity, PD). It is often—but controversially—assumed that these putative measures of niche space are at a minimum correlated and perhaps redundant, since more evolutionary time allows for greater accumulation of trait changes. This theoretical expectation remains surprisingly poorly evaluated, particularly in the context of multivariate measures of trait diversity. We evaluated the relationship between phylogenetic diversity and trait diversity using analytical and simulation‐based methods across common models of trait evolution. We show that PD correlates with FD increasingly strongly as more traits are included in the FD measure. Our results indicate that phylogenetic diversity can be a useful surrogate for high‐dimensional trait diversity, but we also show that the correlation weakens when the underlying process of trait evolution includes variation in rate and optima

Explaining ecosystem multifunction with evolutionary models

Ecosystem function is the outcome of species interactions, traits, and niche overlap – all of which are influenced by evolution. However, it is not well understood how the tempo and mode of niche evolution can influence ecosystem function. In evolutionary models where either species differences accumulate through random drift in a single trait or species differences accumulate through divergent selection among close relatives, we should expect that ecosystem function is strongly related to diversity. However, when strong selection causes species to converge on specific niches or when novel traits that directly affect function evolve in some clades but not others, the relationship between diversity and ecosystem function might not be very strong. We test these ideas using a field experiment that established plant mixtures with differing phylogenetic diversities and we measured ten different community functions. We show that some functions were strongly predicted by species richness and mean pairwise phylogenetic distance (MPD, a measure of phylogenetic diversity), including biomass production and the reduction of herbivore and pathogen damage in polyculture, while other functions had weaker (litter production and structural complexity) or nonsignificant relationships (e.g., flower production and arthropod abundance) with MPD and richness. However, these divergent results can be explained by different models of niche evolution. These results show that diversity‐ecosystem function relationships are the product of evolution, but that the nature of how evolution influences ecosystem function is complex

Opposing community assembly patterns for dominant and non-dominant plant species in herbaceous ecosystems globally

Biotic and abiotic factors interact with dominant plants—the locally most frequent or with the largest coverage—and nondominant plants differently, partially because dominant plants modify the environment where nondominant plants grow. For instance, if dominant plants compete strongly, they will deplete most resources, forcing nondominant plants into a narrower niche space. Conversely, if dominant plants are constrained by the environment, they might not exhaust available resources but instead may ameliorate environmental stressors that usually limit nondominants. Hence, the nature of interactions among nondominant species could be modified by dominant species. Furthermore, these differences could translate into a disparity in the phylogenetic relatedness among dominants compared to the relatedness among nondominants. By estimating phylogenetic dispersion in 78 grasslands across five continents, we found that dominant species were clustered (e.g., co-dominant grasses), suggesting dominant species are likely organized by environmental filtering, and that nondominant species were either randomly assembled or overdispersed. Traits showed similar trends for those sites (<50%) with sufficient trait data. Furthermore, several lineages scattered in the phylogeny had more nondominant species than expected at random, suggesting that traits common in nondominants are phylogenetically conserved and have evolved multiple times. We also explored environmental drivers of the dominant/nondominant disparity. We found different assembly patterns for dominants and nondominants, consistent with asymmetries in assembly mechanisms. Among the different postulated mechanisms, our results suggest two complementary hypotheses seldom explored: (1) Nondominant species include lineages adapted to thrive in the environment generated by dominant species. (2) Even when dominant species reduce resources to nondominant ones, dominant species could have a stronger positive effect on some nondominants by ameliorating environmental stressors affecting them, than by depleting resources and increasing the environmental stress to those nondominants. These results show that the dominant/nondominant asymmetry has ecological and evolutionary consequences fundamental to understand plant communities.EEA Santa CruzFil: Arnillas, Carlos Alberto. University of Toronto Scarborough. Department of Physical and Environmental Sciences; Canadá.Fil: Borer, Elizabeth T. University of Minnesota; Estados UnidosFil: Seabloom, Eric W. University of Minnesota; Estados UnidosFil: Alberti, Juan. Universidad Nacional de Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Marinas y Costeras; Argentina.Fil: Baez, Selene. Escuela Politécnica Nacional. Department of Biology; Ecuador.Fil: Bakker, Jonathan D. University of Washington. School of Environmental and Forest Sciences; Estados UnidosFil: Boughton, Elizabeth H. Archbold Biological Station. Venus, Florida; Estados UnidosFil: Buckley, Yvonne M. Trinity College Dublin. School of Natural Sciences, Zoology; IrlandaFil: Bugalho, Miguel Nuno. University of Lisbon. Centre for Applied Ecology Prof. Baeta Neves (CEABN-InBIO). School of Agriculture; Portugal.Fil: Donohue, Ian. Trinity College Dublin. School of Natural Sciences, Zoology; IrlandaFil: Dwyer, John. University of Queensland. School of Biological Sciences; Australia.Fil: Firn, Jennifer. Queensland University of Technology (QUT); Australia.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Cadotte, Marc W. University of Toronto Scarborough. Department of Biological Sciences; Canadá.Fil: Cadotte, Marc W. University of Toronto. Department of Ecology and Evolutionary Biology; Canadá

Nothing lasts forever: Dominant species decline under rapid environmental change in global grasslands

1. Dominance often indicates one or a few species being best suited for resource capture and retention in a given environment. Press perturbations that change availability of limiting resources can restructure competitive hierarchies, allowing new species to capture or retain resources and leaving once dominant species fated to decline. However, dominant species may maintain high abundances even when their new environments no longer favour them due to stochastic processes associated with their high abundance, impeding deterministic processes that would otherwise diminish them. 2. Here, we quantify the persistence of dominance by tracking the rate of decline in dominant species at 90 globally distributed grassland sites under experimentally elevated soil nutrient supply and reduced vertebrate consumer pressure. 3. We found that chronic experimental nutrient addition and vertebrate exclusion caused certain subsets of species to lose dominance more quickly than in control plots. In control plots, perennial species and species with high initial cover maintained dominance for longer than annual species and those with low initial cover respectively. In fertilized plots, species with high initial cover maintained dominance at similar rates to control plots, while those with lower initial cover lost dominance even faster than similar species in controls. High initial cover increased the estimated time to dominance loss more strongly in plots with vertebrate exclosures than in controls. Vertebrate exclosures caused a slight decrease in the persistence of dominance for perennials, while fertilization brought perennials' rate of dominance loss in line with those of annuals. Annual species lost dominance at similar rates regardless of treatments. 4. Synthesis. Collectively, these results point to a strong role of a species' historical abundance in maintaining dominance following environmental perturbations. Because dominant species play an outsized role in driving ecosystem processes, their ability to remain dominant—regardless of environmental conditions—is critical to anticipating expected rates of change in the structure and function of grasslands. Species that maintain dominance while no longer competitively favoured following press perturbations due to their historical abundances may result in community compositions that do not maximize resource capture, a key process of system responses to global change.EEA Santa CruzFil: Wilfahrt, Peter A. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados UnidosFil: Seabloom, Eric William. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados UnidosFil: Bakker, Jonathan D. University of Washington. School of Environmental and Forest Sciences; Estados Unidos.Fil: Biederman, Lori A. Iowa State University. Department of Ecology, Evolution, and Organismal Biology; Estados UnidosFil: Bugalho, Miguel N. University of Lisbon. Centre for Applied Ecology “Prof. Baeta Neves” (CEABN-InBIO). School of Agriculture; Portugal.Fil: Cadotte, Marc W. University of Toronto Scarborough. Department of Biological Sciences; Canadá.Fil: Caldeira, Maria C. University of Lisbon. Forest Research Centre. School of Agriculture; Portugal.Fil: Catford, Jane A. King’s College London. Department of Geography; Reino UnidoFil: Catford, Jane A. University of Melbourne. School of Agriculture, Food and Ecosystem Sciences; Australia.Fil: Chen, Qingqing. Peking University. College of Urban and Environmental Science; China.Fil: Chen, Qingqing. German Centre for Integrative Biodiversity Research (iDiv). Halle-Jena-Leipzig; AlemaniaFil: Donohue, Ian. Trinity College Dublin. School of Natural Sciences. Department of Zoology; IrlandaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral.; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Borer, Elizabeth T. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados Unido