Understanding evolutionary processes during past Quaternary climatic cycles: Can it be applied to the future?

Climate change affected ecological community make-up during the Quaternary which was probably both the cause of, and was caused by, evolutionary processes such as species evolution, adaptation and extinction of species and populations

Soil biodiversity: functions, threats and tools for policy makers

Human societies rely on the vast diversity of benefits provided by nature, such as food, fibres, construction materials, clean water, clean air and climate regulation. All the elements required for these ecosystem services depend on soil, and soil biodiversity is the driving force behind their regulation. With 2010 being the international year of biodiversity and with the growing attention in Europe on the importance of soils to remain healthy and capable of supporting human activities sustainably, now is the perfect time to raise awareness on preserving soil biodiversity. The objective of this report is to review the state of knowledge of soil biodiversity, its functions, its contribution to ecosystem services and its relevance for the sustainability of human society. In line with the definition of biodiversity given in the 1992 Rio de Janeiro Convention, soil biodiversity can be defined as the variation in soil life, from genes to communities, and the variation in soil habitats, from micro-aggregates to entire landscapes. Bio Intelligence Service, IRD, and NIOO, Report for European Commission (DG Environment

Applying trait-based models to achieve functional targets for theory-driven ecological restoration

Manipulating community assemblages to achieve functional targets is a key component of restoring degraded ecosystems. The response-and-effect trait framework provides a conceptual foundation for translating restoration goals into functional trait targets, but a quantitative framework has been lacking for translating trait targets into assemblages of species that practitioners can actually manipulate. This study describes new trait-based models that can be used to generate ranges of species abundances to test theories about which traits, which trait values and which species assemblages are most effective for achieving functional outcomes. These models are generalisable, flexible tools that can be widely applied across many terrestrial ecosystems. Examples illustrate how the framework generates assemblages of indigenous species to (1) achieve desired community responses by applying the theories of environmental filtering, limiting similarity and competitive hierarchies, or (2) achieve desired effects on ecosystem functions by applying the theories of mass ratios and niche complementarity. Experimental applications of this framework will advance our understanding of how to set functional trait targets to achieve the desired restoration goals. A trait-based framework provides restoration ecology with a robust scaffold on which to apply fundamental ecological theory to maintain resilient and functioning ecosystems in a rapidly changing world

NEW INSIGHTS IN THE ECOLOGY AND EVOLUTION OF PLANT NITROGEN LIMITATION

Under increasing additions of reactive nitrogen (N) to the planet via anthropogenic N deposition and excess fertilization, some plant species will thrive while others will not. This may seem counterintuitive, as the growth of most plants is thought to be limited by soil N, but recent evidence shows that excess N can reduce plant community composition, alter plant-microbial interactions, and lead to fundamental alterations in plant growth and fitness. Yet, we lack the ability to predict which plant species will be winners or losers in soil N enrichment scenarios. The primary goal of my dissertation was to examine variation in plant growth responses to N enrichment and whether ecological and evolutionary factors explain such variation. These factors, according to current literature, should include aspects of past evolution such as phylogeny and evolutionary differentiation in resource use traits, nutrient co-limitation, and interactions with root-associated microbes. Because variation in plant responses to soil N enrichment challenges the paradigm in ecology that productivity of all plants is N-limited or N co-limited, a second goal of my dissertation was to determine how this and other recent work changes our understanding of the terrestrial N and carbon (C) cycles and feedbacks between soil N gradients and evolution under global change.In my first chapter, I used a global dataset of plant biomass responses to N fertilization and evolutionary models to show that species vary in the direction and magnitude with which they respond to N enrichment (with more than one in four species responding negatively or neutrally), and that two aspects of past evolution (phylogenetic relatedness and selection associated with constraints on resource use) govern responses to N enrichment. In my second and third chapters, I implemented two greenhouse fertilization experiments and subsets of the 30 functionally diverse tree species within the genus Eucalyptus that are native to Tasmania, Australia. The main result from these experiments was that phylogenetic patterns in biomass responses to N enrichment are associated with phylogenetic variation in root function (specific root length and interactions with ectomycorrhizal fungi), but not co-limitation by phosphorus (despite the fact that Tasmanian eucalypts occur across strong soil phosphorus gradients). In my fourth chapter, I reviewed how this and other current research challenges long-held and fundamental assumptions regarding the source, plant use, and microbial transformations of N and provides insights into eco-evolutionary feedbacks and C cycling under global change. Overall, my dissertation has used major theories in plant ecology and evolution to explain the variation in plant responses to global change, and synthesized research that highlights new understanding of the drivers and consequences of terrestrial N cycling

Resilience of soil microbial communities to metals and additional stressors : DNA-based approaches for assessing "Stress-on-Stress" responses

International audienceMany microbial ecology studies have demonstrated profound changes in community composition caused by environmental pollution, as well as adaptation processes allowing survival of microbes in polluted ecosystems. Soil microbial communities in polluted areas with a long-term history of contamination have been shown to maintain their function by developing metal-tolerance mechanisms. In the present work, we review recent experiments, with specific emphasis on studies that have been conducted in polluted areas with a long-term history of contamination that also applied DNA-based approaches. We evaluate how the "costs" of adaptation to metals affect the responses of metal-tolerant communities to other stress factors ("stress-on-stress"). We discuss recent studies on the stability of microbial communities, in terms of resistance and resilience to additional stressors, focusing on metal pollution as the initial stress, and discuss possible factors influencing the functional and structural stability of microbial communities towards secondary stressors. There is increasing evidence that the history of environmental conditions and disturbance regimes play central roles in responses of microbial communities towards secondary stressors

An integrative approach to understanding microbial diversity: from intracellular mechanisms to community structure

Trade-offs have been put forward as essential to the generation and maintenance of diversity. However, variation in trade-offs is often determined at the molecular level, outside the scope of conventional ecological inquiry. In this study, we propose that understanding the intracellular basis for trade-offs in microbial systems can aid in predicting and interpreting patterns of diversity. First, we show how laboratory experiments and mathematical models have unveiled the hidden intracellular mechanisms underlying trade-offs key to microbial diversity: (i) metabolic and regulatory trade-offs in bacteria and yeast; (ii) life-history trade-offs in bacterial viruses. Next, we examine recent studies of marine microbes that have taken steps toward reconciling the molecular and the ecological views of trade-offs, despite the challenges in doing so in natural settings. Finally, we suggest avenues for research where mathematical modelling, experiments and studies of natural microbial communities provide a unique opportunity to integrate studies of diversity across multiple scales

Urban Evolution: The Role of Water

The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It allows urban planning, management, and restoration to move beyond reactive management to predictive management based on past observations of consistent patterns. Here, we define and review a glossary of core concepts for studying urban evolution, which includes the mechanisms of urban selective pressure and urban adaptation. Urban selective pressure is an environmental or societal driver contributing to urban adaptation. Urban adaptation is thesequential process by which an urban structure, function, or services becomes more fitted to its changing environment or human choices. The role of water is vital to driving urban evolution as demonstrated by historical changes in drainage, sewage flows, hydrologic pulses, and long-term chemistry. In the current paper, we show how hydrologic traits evolve across successive generations of urban ecosystems via shifts in selective pressures and adaptations over time. We explore multiple empirical examples including evolving: (1) urban drainage from stream burial to stormwater management; (2) sewage flows and water quality in response to wastewater treatment; (3) amplification of hydrologic pulses due to the interaction between urbanization and climate variability; and (4) salinization and alkalinization of fresh water due to human inputs and accelerated weathering. Finally, we propose a new conceptual model for the evolution of urban waters from the Industrial Revolution to the present day based on empirical trends and historical information. Ultimately, we propose that water itself is a critical driver of urban evolution that forces urban adaptation, which transforms the structure, function, and services of urban landscapes, waterways, and civilizations over time