Biodiversity matters in a changing world

It is now widely accepted that the climate of our planet is changing, but it is still hard to predict the consequences of these changes on ecosystems. The impact is worst at the poles, with scientists concerned that impacts at lower latitudes will follow suit. Canada has a great responsibility and potential for studying the effects of climate changes on the ecological dynamics, given its geographical location and its scientific leadership in this field. The 5th annual meeting of the Canadian Society for Ecology and Evolution was held in the International Year of Biodiversity, to share recent advances in a wide variety of disciplines ranging from molecular biology to behavioural ecology, and to integrate them into a general view that will help us preserve biodiversity and limit the impact of climate change on ecosystems.     

Biological diversity in a changing world

From the pioneering explorations of Joseph Banks (later a President of the Royal Society), to the present day, a great deal has been learnt about the extent, distribution and stability of biological diversity in the world. We now know that diverse life can be found even in the most inhospitable places. We have also learned that biological diversity changes through time over both large and small temporal scales. These natural changes track environmental conditions, and reflect ecological and evolutionary processes. However, anthropogenic activities, including overexploitation, habitat loss and climate change, are currently causing profound transformations in ecosystems and unprecedented loss of biological diversity. This series of papers considers temporal variation in biological diversity, examines the extent of human-related change relative to underlying natural change and builds on these insights to develop tools and policies to help guide us towards a sustainable future.     

The family in a changing world

Increasing numbers of young mothers in the work force, more and more children requiring extrafamilial care, high rates of divorce, lower rates of remarriage, increasing numbers of female-headed households, growing numbers of zero-parent families, and significant occurrences of child maltreatment are just some of the social indicators indicative of the family in a changing world. These trends and their consequences for children are described and then examined from the perspectives of microeconomic theory, the relative-income hypothesis, sex-ratio theory, and one form of modernization theory. The paper concludes with a preliminary examination of the added explanatory power provided by evolutionary theory.     

Trophic interactions in a changing world

Across the biosphere, rapid and accelerating changes in land use, climate and atmospheric composition driven primarily by anthropogenic forces are known to exert major influences on the productivity, biodiversity and sustainable provision of ecosystem goods and services. Thus far, many studies assessing the ecological consequences of global change have focussed on single trophic levels. However, understanding these changes and predicting their consequences may benefit from unravelling how interactions between primary producers, primary, and secondary consumers (plants, herbivores and carnivores) are being affected. Conservation and restoration may be improved when assessing species and their interactions on appropriate scales, while acknowledging that above- and belowground biota are ecologically linked. Selection pressures on one species may depend on others, so that species loss means more for diversity than just loss of a single taxon. It may also result in the loss of other species of the same or different trophic levels and in the dilution, or even loss, of various selection pressures. We review a number of discussions on trophic interactions in a changing world in relation to (i) the scale of ecosystem response to environmental change with emphasis on the soil subsystem, (ii) the linkage of above- and belowground subsystems and (iii) natural selection and the stability of community structure and ecosystem functioning. We discuss the need to bring together isolated sub-disciplines of ecology in order to understand the implications of global changes for ecosystem processes.

Zusammenfassung

In der gesamten Biosphäre üben schnelle und sich beschleunigende Veränderungen in der Landnutzung, des Klimas und der atmosphärischen Zusammensetzung, die vor allem durch anthropogene Kräfte angetrieben werden, größten Einfluss auf die Produktivität, die Biodiversität und die nachhaltige Bereitstellung von Ökosystemgütern und –leistungen aus. Bisher konzentrierten sich viele Untersuchungen, die ökologische Konsequenzen des globalen Wandels abschätzen, auf einzelne trophische Level. Das Verständnis dieser Veränderungen und die Vorhersage ihrer Konsequenzen kann jedoch davon profitieren, dass enträtselt wird, wie die Interaktionen zwischen den Primärproduzenten und den primären und sekundären Konsumenten (Pflanzen, Herbivore und Karnivore) beeinflusst werden. Naturschutz und –wiederherstellung kann verbessert werden, wenn die Arten und ihre Interaktionen auf angemessenen Skalen und unter Berücksichtigung, dass ober- und unterirdische Biota ökologisch miteinander verbunden sind, eingeschätzt werden. Der Selektionsdruck auf eine Art kann von anderen Arten abhängen, so dass der Verlust einer Art mehr für die Diversität bedeutet als nur den reinen Verlust eines Taxons. Er kann ebenso den Verlust anderer Arten des gleichen oder eines anderen trophischen Levels zur Folge haben sowie die Abschwächung oder sogar den Verlust von verschiedenen Selektionsdrücken. Wir geben einen Überblick über die Diskussionen zu trophischen Interaktionen in einer sich verändernden Welt in Bezug auf (i) die Skala der Ökosystemantwort auf Umweltveränderungen mit Betonung des Bodensubsystems, (ii) die Verbindung zwischen ober- und unterirdischen Subsystemen und (iii) die natürliche Selektion und die Stabilität der Gemeinschaftsstruktur sowie der Ökosystemfunktion. Wir diskutieren die Notwendigkeit isolierte Subdisziplinen der Ökologie zusammen zu führen, um die Implikationen des globalen Wandels für Ökosystemprozesse zu verstehen.     

Mate choice in a changing world

Human activities by altering environmental conditions are influencing the mate choice of animals. This is by impacts on: (i) the production and expression of traits evaluated by mate choosers; (ii) the transmission of information about potential mates to choosers; (iii) the reception and processing of the information by choosers; and (iv) the final mate choice. Here, I first discuss how these four stages of the mate‐choice process can be altered by environmental change, and how these alterations, in turn, can influence individuals, populations, and communities. Much evidence exists for human‐induced environmental changes influencing mate choice, but the consequences for the fitness of courters and choosers are less well known, and even less is known about the impact on population dynamics, species interactions and community composition. More evidence exists for altered mate‐choice systems influencing interspecific matings and thereby community composition and biodiversity. I then consider whether plastic adjustments and evolutionary changes can rescue adaptive mate‐choice systems, and reflect on the possibility of non‐adaptive mate‐choice systems becoming less maladaptive under environmental change. Much evidence exists for plastic adjustments of mate‐choice systems, but whether these are adaptive is seldom known, as is the contribution of genetic changes. Finally, I contemplate the possibility of mate‐choice systems rescuing populations from decline in changing environments. I explain how this is context dependent with both positive and negative outcomes possible. In summary, while much evidence exists for human‐induced environmental changes influencing mate‐choice systems, less is known about the consequences for ecological and evolutionary processes. Considering the importance that mate choice plays in determining individual fitness and population viability, the effects of environmental change on mate‐choice systems should be considered in studies on the ecological and evolutionary consequences of human disturbances to habitats.     

Conservation planning in a changing world

Conservation planning is the process of locating, configuring, implementing and maintaining areas that are managed to promote the persistence of biodiversity and other natural values. Conservation planning is inherently spatial. The science behind it has solved important spatial problems and increasingly influenced practice. To be effective, however, conservation planning must deal better with two types of change. First, biodiversity is not static in time or space but generated and maintained by natural processes. Second, humans are altering the planet in diverse ways at ever faster rates.     

Macrophysiology for a changing world

The Millennium Ecosystem Assessment (MA) has identified climate change, habitat destruction, invasive species, overexploitation and pollution as the major drivers of biodiversity loss and sources of concern for human well-being. Understanding how these drivers operate and interact and how they might be mitigated are among the most pressing questions facing humanity. Here, we show how macrophysiology--the investigation of variation in physiological traits over large geographical, temporal and phylogenetic scales--can contribute significantly to answering these questions. We do so by demonstrating, for each of the MA drivers, how a macrophysiological approach can or has helped elucidate the impacts of these drivers and their interactions. Moreover, we illustrate that a large-scale physiological perspective can provide insights into previously unrecognized threats to diversity, such as the erosion of physiological variation and stress tolerance, which are a consequence of the removal of large species and individuals from the biosphere. In so doing we demonstrate that environmental physiologists have much to offer the scientific quest to resolve major environmental problems.     

Antarctic terrestrial biodiversity in a changing world

Recent analyses of Antarctic terrestrial biodiversity data, in combination with molecular biological studies, have created a new paradigm that long-term persistence and regional isolation are general features of most of the major groups of Antarctic terrestrial biota, overturning the previously widely assumed view of a generally recent colonisation history. This paradigm, as well as incorporating a new and much longer timescale in which to consider the evolution and adaptation of Antarctic terrestrial biota, opens important new cross-disciplinary linkages with geologists and glaciologists seeking to unravel the history of the continent itself. This unique biota now faces the twin challenges of responding to the complex processes of climate change facing some parts of the continent, and the direct impacts associated with human occupation and activity. In many instances, this biota is likely to benefit, initially at least, from the current environmental changes, and there is an expectation of increased production, biomass, population size, community complexity, and colonisation. However, the impacts of climate change may themselves be outweighed by other, direct, impacts of human activities, and in particular, the introduction of non-indigenous organisms from which until recently the terrestrial ecosystems of the continent have been protected. The Antarctic research community and those responsible for governance under the Antarctic treaty system are faced with the pressing challenges of (1) ensuring there is sufficient baseline monitoring and survey activity to enable identification of these changes, however caused and (2) ensuring that effective operational management and biosecurity procedures are in place to minimise the threat from anthropogenic activities.