BIOCHANGE Seminars are part of a broader programme of seminars in Ecology and Evolution, organised by David Vieites. Seminars take place in the “Salón de Actos” of the MNCN at 12 pm. Everyone is welcomed.
Pseudo-absences, MAXENT and point processes - Unifying methods for species distribution modelling using occurrence data (28th April 2010, 12 pm in “Sala de Juntas”)
David Warton, The University of New South Wales, Australia
Technology has enabled rapid advances in data analysis across multiple disciplines – with the collection of new types of data posing new challenges, and with the development of new methods for analysing data rapidly increasing our analytical capacity. An important example is species distribution modelling using occurrence data – geographic information systems (GIS) enable the study of environmental variables at a spatial resolution far higher than previously possible, and new methods of data analysis are rapidly being developed for studying how such environmental variables relate to species occurrence records. In this talk, I show that three different methods of analysis, from the ecology, machine learning and statistical literatures, are all equivalent. This significant advance overcomes important methodological weaknesses of the two most widely used methods for species distribution modelling using occurrence data, pseudo-absence and MAXENT methods, via the use of a point process model specification. One important issue that can be addressed via this method that has not been effectively answered previously is the role of spatial resolution in species distribution modelling. The increased functionality available via point process models will be discussed, and a new method for accounting for observer bias proposed.
Biosketch:See here.
The Mediterranean Sea as a “cul-de-sac” for endemic fishes facing climate change (26th March 2010, 12 pm in “Salon de Actos”)
Francois Guilhaumon, Université Montpellier II, France
The Mediterranean Sea is a hotspot of biodiversity, and global warming is expected to have a significant influence on its endemic fish species. However, no previous studies have predicted whether these fish species will experience geographic range extensions or contractions as a consequence of global warming. Here, we projected the potential future climatic niches of 75 Mediterranean endemic fish species based on a global warming scenario implemented with the Mediterranean model OPAMED8 and a multi-model inference, including model-based uncertainty. By 2070-2099, the average surface temperature of the Mediterranean Sea was projected to warm up by 3.1°C. Projections of 2041-2060 predicted that 25 species would qualify for the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List, and 6 species would become extinct. By 2070-2099, 45 species were expected to qualify for the IUCN Red List while 14 were expected to become extinct. By the middle of the 21st century, the coldest areas of the Mediterranean (Adriatic Sea and Gulf of Lion) would act as a refuge for cold-water species, but by the end of the century, those areas were projected to become a “cul-de-sac” that would drive those species towards extinction. In addition, the range size of endemic species was projected to undergo extensive fragmentation, which is a potentially aggravating factor. Since a majority of endemic fishes are specialists, regarding substrate and diet, we may expect a reduced ability to track projected climatic niches. As a whole, 25% of the Mediterranean continental shelf was predicted to experience a total modification of endemic species assemblages by the end of the 21st century. This expected turnover rate could be mitigated by marine protected areas or accelerated by fishing pressure or competition from exotic fishes. It remains a challenge to predict how these assemblage modifications might affect
ecosystem function.
Biosketch:See here.
Predicting biological invasions: can we project the niche in space?
(18th february 2010, 12 pm in “Salon de Actos”)
Dr. Antoine Guisan, University of Lausanne, Switzerland
The worldwide increase of biological invasions puts biodiversity at threat. Robust tools are required to better anticipate and manage ongoing and future invasions. Species Distribution Modeling (SDM) is commonly used to predict potential species distribution but its efficiency may be lowered if changes in the realized niche take place between the native and invaded ranges. These changes may be due to different biotic interactions, rapid evolution or dispersal limitation. Here, we present a new multivariate analytical framework in a gridded climatic space to quantify niche change during biological invasions. We test for niche changes in the large scale climatic niche of 43 plant species native to Eurasia (EU) or North America (NA) and invasive in EU, NA or Australia (AU). Seventeen species present niche similarity between their native and invaded ranges and seven species tend to move into new environments during the invasion process. Native species’ niche is far more conserved in AU. We then investigated whether the adaptations to new environments are correlated to specific traits. Our study underlines how changes in the observed realized niche of species can strongly bias SDM predictions and possible affect the management of biological invasions.
Emerging threats and research challenges in the tropics
(19th June 2009, 12 pm in “Salon de Actos”)
Prof. William F. Laurance, Smithsonian Tropical Research Institute, Balboa, Panama
I will highlight several new and emerging threats to tropical ecosystems and consider the research challenges these raise. The drivers of tropical forest destruction and key perils to biodiversity have changed over the past two decades. Industrial drivers of forest conversion—such as logging, large-scale soy and cattle farming, oil-palm plantations, and oil and gas development—have escalated in importance in recent decades, buoyed by rapid globalization, economic growth, and rising standards of living in developing nations. Biofuels are likely to grow rapidly as a driver of future forest destruction. Climate change has emerged as a potentially serious cause of change in the tropics, and some fauna, such as amphibians, are being decimated by emerging pathogens. In general, old-growth forests are vanishing rapidly and being replaced by fragmented, secondary, and logged forests. These evolving threats are creating an urgent need for new research. For example, we know far too little about how well secondary and degraded habitats will sustain tropical biodiversity. Much is unknown about how climate change will affect tropical biota at high and low elevations, or how this will interact with ongoing land-use change. Further, we have only the most rudimentary idea of how climate change will affect tropical precipitation—a crucial deficit given the acute sensitivity of tropical forests to drought and fire. Information on environmental synergisms is meager at best. Finally, we need to develop new conservation strategies to deal with the increasingly industrial drivers of deforestation. I will highlight these and other issues on the horizon of tropical conservation science.
Biosketch:See here.
Robust prediction and decision strategies for managing extinction risks under climate change (3rd April 2009, 12 pm in “Salon de Actos”)
Dr. Brendam Wintle, University of Melbourne, Australia
Climate change introduces yet another element of uncertainty to biodiversity conservation planning. The extent to which climate change will exacerbate (or mitigate) existing threats such as habitat fragmentation and feral predation is extremely uncertain and actions that were once successful in mitigating threats may cease to be successful. Robust strategies for predicting the impacts of climate change and the relative benefits and efficiency of competing mitigation and adaptation measures are required. A common approach for predicting species’ responses to climate change uses habitat suitability models or ‘bioclimatic envelopes’. These models use present-day species-environment relationships to project potential distributions of species under future climates. However, predictions of species responses based solely on these projections are incomplete because they fail to account for important processes that influence extinction outcomes. Extinction risks cannot easily be inferred from shifts in suitable bioclimates. I will discuss our current research that aims to address some of the short-comings in existing approaches to predicting climate change impacts by incorporating landscape and population dynamics, species interactions and physiology. Irrespective of which models are used to predict climate change impacts and prioritize management responses, substantial uncertainty about the mechanisms and magnitude of impacts and the most efficient responses strategies will remain. Decision theories that identify the portfolio of actions that maximise the probability of achieving a minimally acceptable biodiversity outcome are useful because they provide a theoretical framework and language for dealing with uncertainty in complex decisions such as how to investment a finite conservation budget to best address climate change impacts. Using the case study of the Australian ‘Great Eastern Ranges’ connectivity project, I’ll demonstrate how decision theory may be used to chose a portfolio of investments that is most robust to uncertainty about climate change impacts, where the objective is to maximize the probability of limiting the number of extinctions in the next 100 years to some pre-specified level.
Biosketch: Brendan Wintle is a Senior Research Fellow in the School of Botany at the University of Melbourne. He is Deputy Director of an Australian Government Research Centre; Applied Environmental Decision Analysis (AEDA www.aeda.edu.au), directed by Hugh Possingham. He specialises in uncertainty and environmental decision-making and publishes widely on technical and policy issues around conservation and natural resource management, including optimal monitoring and adaptive management, systematic conservation planning, population viability analysis, habitat modelling and mapping, Bayesian statistics, and decision theory. Brendan works at the interface between policy and science, serving on Forest Stewardship Council and Australian Forestry Standard reference committees and the Australian Government’s monitoring, evaluation, reporting and improvement advisory group. He provides advice to various State and Commonwealth initiatives including threatened species recovery teams. Brendan has a PhD in ecological modelling from the University of Melbourne (under Mark Burgman) and is a member of the editorial boards of the Journal of Applied Ecology and Diversity and Distributions.
Artificial selection, organismal design, and the aerobic capacity model for the evolution of endothermy (18th March 2009, 12 pm in “Salon de Actos”)
Prof. Jack Hayes, University of Nevada, USA
One of the most important events in vertebrate evolution was the evolution of endothermy. Because endothermy evolved more than 100 million years ago, and because reliable fossilizable indicators of physiology are rare, testing hypotheses about the evolution of endothermy has proven to be challenging. Among the most popular explanations for the evolution of endothermy is the aerobic capacity model. That model posits that endothermy evolved as a correlated response to selection on aerobic capacity (i.e., maximal exercise-induced oxygen consumption or VO2max). A key assumption of the aerobic capacity model is that resting metabolism and VO2max are inescapably, mechanistically linked. While it is not possible to determine whether these characters are necessarily linked (positively correlated) in the animals in which endothermy evolved, it is possible to test whether they are positively correlated in extant terrestrial vertebrates. Hence the aerobic capacity model is falsifiable. We conducted a large-scale artificial selection experiment on VO2max in mice and tested for a correlated response in resting metabolism. VO2max diverged significantly between selected and control lines and there was a significant correlated response in resting metabolism. Consistent with the assumptions of the aerobic capacity model, we found a strong positive genetic correlation between resting metabolism and VO2max at both the whole-animal and mass-independent levels. While this positive genetic correlation is an evolutionary constraint, it is not sufficiently strong to preclude appreciable independent evolution. The approach we have taken is novel in that artificial selection has being used to test a macroevolutionary hypothesis that depends on specific predictions about the nature of organismal design. In addition, our data on genetic architecture of ecologically important physiological traits may prove useful as scientists attempt to predict the consequences of global climate change.
Integrating species biological traits into conservation planning scenarios (13th March 2008, 12 pm in “Salon de Actos”)
Dr. Rafael D. Loyola, Departamento de Biologia Geral, Universidade Federal de Goiás, Brazil
Conservation planning analyses show a striking progression from endeavors targeted at single species or at individual sites, to the systematic assessment of entire taxa at large scales. These, in turn, inform wide-reaching conservation policies and financial investments. Prioritization schemes usually attribute high importance to areas with the highest species richness and endemism or where extensive habitat loss has already taken place. These approaches aim at minimizing biodiversity loss in regions where severe human disturbance to natural habitats has already occurred. However, species respond differently to threats and several factors can influence such responses. Hence, to be ecologically sound these schemes should also include species biological traits into area-setting methods. This can be achieved by mapping evolutionary, ecological, and life-history traits, which are used as constraints in prioritization analyses. This approach allows the construction of different conservation planning scenarios. For instance, one could imagine a scenario in which regions tend to aggregate species that are large-bodied, having at the same time small litter size, long interbirth period, small local population density as well as high phylogenetic diversity. Regions harboring such species assemblages need an urgent intervention because these species are thought to be at imminent risk of extinction. Biological traits could be combined in different ways to generate other scenarios. The inclusion of biological traits into area-setting methods helps to increase the effectiveness of priority-area sets elucidating where conservation is likely to yield best returns at different spatial scales from an ecological perspective.
Biosketch: Rafael D. Loyola is Professor of Ecology and Evolution in the Departamento de Biologia Geral of the Universidade Federal de Goiás, Brazil. His main research interests are the identification of priority areas for terrestrial vertebrate conservation at different spatial scales, the identification of indicator groups for establishing conservation priorities. He is also interested in theoretical/methodological issues on species distribution models, and its implications to conservation biology and reserve network design.
Imprints of past climate change on the European tree flora (23rd October 2008, 12 pm in “Salon de Actos”)
Prof. Jens-Christian Svenning, Department of Biological Sciences, University of Aarhus, Denmark
A key issue in ecology and conservation biology is understanding how climate change affects biodiversity. The Late Pliocene and Pleistocene (2.6 million to 11,500 years ago) is an important period for assessing the impact of climate change due to its multiple oscillations between warm interglacial conditions and cold glacial conditions. Importantly, these climatic changes caused extinctions and dramatic range dynamics in the European flora. I will present evidence that the current plant diversity – both species composition and species richness - in Europe and its geographic patterning are strongly influenced by long-lasting effects of these past climate changes, and discuss the implications for the impacts of 21st century climate change on Europe’s plant diversity.
Diversidad de los mamíferos Mexicanos del Cuaternário (30th June 2008, 12 pm in “Salon de Actos”)
Dr. Joaquín Arroyo-Cabrales, Instituto Nacional de Antropología e Historia, México
Hace más de una década, se creó una base de datos que contiene la información disponible en la literatura, ya sea impresa o sin publicar, acerca de los mamíferos que existieron en el Cuaternario mexicano (120,000 hasta 10,500 años AP). Así, la disponibilidad de más de 15,000 registros procedentes de más de 800 localidades, nos permiten señalar que se conoce la existencia de aproximadamente 250 especies, pertenecientes a 12 órdenes, 43 familias y 146 géneros. De dichas especies, una tercera parte ya no existe en el país, incluyendo aquellas que se extinguieron (p.e. Notoungulata o Mylodontidae), o las que quedaron extirpadas, ya sea del continente (p.e., Proboscidea o Equidae) o del país (p.e. Camelidae o Hydrochoeridae). Los datos indican una composición específica diferente de la mastofauna de fines del Pleistoceno a la actual. Aunque claramente el registro fósil está sesgado hacia los animales de tamaño mediano y grande, se puede ver un patrón en nuestros datos. Si consideramos las especies de los órdenes Artiodactyla, Perissodactyla y Proboscidea que están extintas, y aquellas dentro de los órdenes Xenarthra y Carnivora que pesaron arriba de 100 kg, entonces tenemos que de 78 especies, 63 se extinguieron (80.8%); dicho conjunto incluyó muchos megaherbívoros y los megacarnívoros. Muchas especies expandieron su distribución a latitudes o altitudes más altas o más bajas, por lo que tenían una distribución más norteña o sureña durante el Pleistoceno que en el presente. Las tendencias en los movimientos de los mamíferos tropicales fueron similares a las de los animales de climas templados. Los patrones de distribución actual de varios conjuntos de especies se pueden explicar como resultado del efecto de las glaciaciones pleistocénicas.
A general dynamic theory of oceanic island biogeography (13th June 2008; 12 pm in “Salón de Actos”)
Prof. Robert J. Whittaker, Editor-in-Chief of the Journal of Biogeography, Oxford University Centre for the Environment
MacArthur and Wilson’s dynamic equilibrium model of island biogeography provides a powerful framework for understanding the ecological processes acting on insular populations. However, their model is known to be less successful when applied to systems and processes operating on evolutionary and geological timescales. Here, we present a general dynamic model (GDM) of oceanic island biogeography that aims to provide a general explanation of biodiversity patterns through describing the relationships between fundamental biogeographical processes – speciation, immigration, extinction – through time and in relation to island ontogeny. Analyses are presented for the Azores, Canaries, Galapagos, Marquesas and Hawaii. We develop a theoretical argument from first principles using a series of graphical models to convey key properties and mechanisms involved in the GDM. Based on the premises (1) that emergent properties of island biotas are a function of rates of immigration, speciation and extinction, (2) that evolutionary dynamics predominate in large, remote islands, and (3) that oceanic islands are relatively short-lived landmasses showing a characteristic humped trend in carrying capacity (via island area, topographic variation, etc.) over their life span, we derive a series of predictions concerning biotic properties of oceanic islands. We test a subset of these predictions using regression analyses based largely on data sets for native species and single-island endemics (SIEs) for particular taxa from each archipelago, and using maximum island age estimates from the literature. The empirical analyses test the power of a simple model of diversity: logArea + Time + Time2 model (ATT23 ), relative to other simpler time and area models, using several simple diversity metrics. The ATT2 model provides a more satisfactory explanation than the alternative models evaluated (for example the standard diversity–area models) in that it fits a higher proportion of the data sets tested, although it is not always the most parsimonious solution. The theoretical model developed herein is based on the key dynamic biological processes (migration, speciation, extinction) combined with a simple but general representation of the life cycle of oceanic islands, providing a framework for explaining patterns of biodiversity, endemism and diversification on a range of oceanic archipelagos. The properties and predictions derived from the model are shown to be broadly supported (1) by the empirical analyses presented, and (2) with reference to previous phylogenetic, ecological and geological studies.
Biosketch:See here.
Species Richness under Niche Dynamics Processes (14th May 2008; 12 pm in “Salón de Actos”)
Thiago Rangel, Ecology & Evolutionary Biology Department, The University of Connecticut
Evolutionary processes underlying spatial patterns in species richness remain largely unexplored, and correlative studies lack the theoretical basis to explain these patterns in evolutionary terms. In this study, we develop a spatially explicit simulation model to evaluate, under a pattern-oriented modeling approach, whether evolutionary niche dynamics (the balance between niche conservatism and niche evolution processes) can provide a parsimonious explanation for patterns in species richness. We model the size, shape, and location of species’ geographical ranges in a multivariate heterogeneous environmental landscape by simulating an evolutionary process in which environmental fluctuations create geographic range fragmentation, which, in turn, regulates speciation and extinction. We applied the model to the South American domain, adjusting parameters to maximize the correspondence between observed and predicted patterns in richness of about 3,000 bird species. Predicted spatial patterns, which closely resemble observed ones (r 2p 0.795), proved sensitive to niche dynamics processes. Our simulations allow evaluation of the roles of both evolutionary and ecological processes in explaining spatial patterns in species richness, revealing the enormous potential of the link between ecology and historical biogeography under integrated theoretical and methodological frameworks.
Approaches for Dealing with Variability and Uncertainty in Threatened Species Assessments (11th April 2008)
Prof. H. Resit Akçakaya
Department of Ecology and Evolution
Stony Brook University, New York, USA
Assessment of the status of threatened species, as well as evaluation of options for their conservation and recovery, increasingly rely on quantitative methods, including population viability analysis (PVA) and rule-based approaches such as the IUCN Red List Criteria. The data required for these methods are often uncertain and variable, leading to two related issues: quantifying the uncertainty and the variability in these parameters, and incorporating them into the quantitative methods in a consistent way. This talk will present and demonstrate a set of approaches that have been developed to address these two issues. These approaches include data analysis methods that input uncertain monitoring data and output estimates of temporal variables (e.g., the rate of population reduction, and existence of continuing decline and extreme fluctuations), and spatial variables (area of occupancy and extent of occurrence) used in IUCN Red List assessments, quantifying uncertainties from several sources. Temporal variables may be uncertain because of observation error and uncertainty of the contribution of different subpopulations to the overall species trends. Spatial variables may be uncertain because observations may have different levels of reliability (e.g., some are old or unconfirmed), and because the location information is imprecise (coordinates of occurrences are measured with error). In addition, the extent of occurrence can be uncertain because of uncertainty about whether and to what extent to exclude discontinuities in the distribution; and the area of occupancy can be uncertain because of inconsistencies in the resolution and position of the measurement grid. Other approaches that will be discussed focus on incorporating temporal and spatial variability in the habitat and demography of species into PVA models used to assess population and metapopulation viability. Preliminary results indicate that these uncertainties can have substantial effects on the assessed status of species, as well as the ranking of management options in terms of their effect on species viability.
Multiple Working Hypotheses in theory and practice (…or have one’s scientific cake and eat it too) (9th April 2008)
Prof. Barry Brook
Director of the Research Institute for Climate Change and Sustainability at the University of Adelaide, Australia
Western science and philosophy have a long tradition of thought concerned explicitly with the notions of observation, inference, truth, and prediction. Yet the statistical methods that we would recognize today are less than 100 years old. This raises a question: What were Hooke, Linnaeus, Cuvier, and Darwin doing before the development of the P value? Their substantial contributions to biology remind us that analytic thought is only one component of science. In fact there is a spectrum of possible approaches to analyses in natural science, from repeatable experimental designs with controlled treatments to diachronic observational studies in which the luxury of control is simply not tenable. The method of multiple working hypotheses, developed by the 19th-century geologist T. C. Chamberlin, is an important philosophical contribution to the domain of hypothesis construction in science, because it espouses a worldview that values lateral thinking and multiple possibilities. The concept is particularly pertinent to recent debate over the relative merits of two different statistical paradigms: null hypothesis testing and model selection. I will talk about why all natural scientists should be thinking about their work in these broader philosophical terms – and then provide some examples which illustrate how these methods can be implemented in practice, using information-theoretic, Bayesian, or other more ad hoc model-averaging approaches.
Biosketch:See here.
New quantitative tools for the analysis of landscape connectivity: graphs and habitat availability metrics (28th March 2008)
Dr. Santiago Saura
PlanForBio research group, University of Lleida
The rapid development of quantitative methods in landscape ecology offers a wide range of spatial metrics for the analysis of landscape configuration and connectivity. However, their characteristics and performance have not been sufficiently examined and, although they may be intuitively appealing, many of these metrics present important limitations that do not make them adequate for decision making in conservation and territorial planning. Graph structures are a powerful and effective way of representing the landscape network and performing complex connectivity analyses, offering the ability to identify patches that are very important to habitat connectivity and thus to long-term population persistence across the landscape. Graph-based metrics are a suitable alternative to spatially explicit population models for connectivity assessments at large scales, and possess a good balance between data requirements and the degree of detail in the results. We present improved graph connectivity metrics that have been recently developed based on the habitat availability concept, which consists in considering a habitat patch itself as a space where connectivity exists. These metrics integrate in a single measure the connected area existing within the patches (intrapatch connectivity) with the one made available due to the connections between different habitat patches (interpatch connectivity). These metrics overcome several limitations of various previously used connectivity metrics and are particularly suited to conservation and territorial planning through an adequate reaction to relevant spatial changes and an appropriate evaluation of the critical landscape elements for the maintenance of connectivity. These new metrics can be partitioned in three separate fractions that quantify the different ways in which individual landscape elements (patches, links) contribute to overall habitat connectivity and availability in the landscape (including stepping stone effects). These fractions are measured in the same units and can be directly compared and summed up, avoiding the problematic combination of metrics with different backgrounds and characteristics.
Biosketch:See here.
Mountains and diversity – what determines large-scale patterns of species-richness? (13th February 2008)
Prof. Carsten Rahbek, Director NSF Center for Macroecology, Editor-in-Chief of Ecography, Institute of Biology, University of Copenhagen
Mountains are the most biological diverse regions in the world – and altitudinal gradients may be a perfect template to elucidate the role of climate, history and topographic heterogeneity in determine the distribution of life on Earth. This talk will demonstrate the role of mountains in shaping global and continental species richness pattern and discuss the usefulness of altitudinal species-richness gradients in elucidating mechanisms controlling level of species richness. Using this mountain theme, the talk will touch upon fundamental problems and challenges to macroecological research illuminating why – despite two centuries of exploration – our understanding of factors determining the distribution of life on Earth is in many ways still in its infancy. This is partly due to an inappropriate statistical approach to testing diversity hypotheses, where we have relied on correlative approaches to infer causality. Also, much of the disagreement about governing processes of variation in species richness may be the result of the implicit, but wrong assumption that patterns and mechanisms are scale invariant. This can lead to unidirectional biases in hypothesis testing, which can cause favoring, wrongly, certain (climate related) hypothesis over competing hypothesis. Lack of significant progress have also largely been due to neglecting the role of range-sizes despite the fact that patterns of species richness and species range size distributions are intertwined and interrelated. Overall, the presented results will illuminate that our understanding of the role of contemporary climate on species richness patterns is perhaps less powerful than anticipated.
Connectivity in the design of protected area networks (2nd November 2007; 4pm in “Sala de Juntas”)
Dr. Jorge Orestes Cerdeira, Centro de Estudos Florestais, Instituto Superior de Agronomia, Technical Univ. Lisbon.
A number of problems associated with the spatial structure in the design of networks of protected areas are not trivial, and solutions are not readily approximated intuitively. One such issue is that of identifying minimum size networks capturing the regional species assemblage, where some level of adjacency or connectivity between areas is achieved. These spatial issues fit within the framework of graph theory. I will address three different problems concerning connectivity in the design of protected areas for conservation. This work has been carried out with Diogo Alagador, Kevin Gaston and Leonor Pinto.
Biosketch: See here.
Species Pool Effects on the Functional Structure of African Mammal Assemblages (31st October 2007)
Dr. Joaquín Hortal, NERC Centre for Population Biology, Imperial College London
The assembly of species in local assemblages depends on the species available in the regional pool. However, little is known about how the functional structure of these assemblages is affected by their species pool. We test to what extent such functional structure is a product of the functional characteristics of the species available in the pool in 16 mammal assemblages located in the Paleotropical realm. We also assess if such effect differs from the dependence on the pool of species composition.
Different geographic definitions of the regional pool have been proposed, and also of the degree of pertenence of each species to such pool. Therefore, we used seven different definitions of pool (weighted and unweighted circle, biome and dispersal field, and the whole biogeographic region), accounting for different geographic definitions and degrees of pertenence to the pool. Weighted pools provide better approximations to the local structure of African mammal assemblages than unweighted ones. Here, geographic distance describes species assembly better than the biogeographic signal contained in the number of species shared with the studied locality. The most striking of our results is the high importance of the functional characteristics of the species present in the pool on the functional structure of local assemblages. Such effect almost doubles the effect on species composition; while median similarities between random assemblages and local checklists range between 0.3 and 0.4 for species composition, the go above 0.7 for functional structure in most cases. Although some sites located in restricted biomes present deviations from such pattern, our results provide strong support for the hypothesis of an important effect of regional species pool in the ecological structuration of African communities.
Biosketch: See here.
Niche conservatism and climate change as drivers of the global bird diversity gradient (19th October 2007)
Prof. Brad A. Hawkins, University of California Irvine
It is now well known that broad-scale diversity gradients are strongly influenced by climate, especially the interaction between water and energy. However, although this may explain how currently existing species distribute themselves geographically, it does not address how species are added to or removed from the global species pool in evolutionary time. In this talk I will argue that for birds at least, niche conservatism in the face of the historical pattern of global climate change accounts for the evolutionary component of their diversity gradient. This mechanism allows us to link the ecological and evolutionary components of diversity via climatic effects operating in the past, present, and future.
Biosketch: See here.
Dealing with Global Warming: How Ancient Ideas in Western Civilization and Some Modern Ecological Science Make This Difficult (21st June 2007)
Prof. Emeritus Dan Botkin, University California San Diego
I believe that the fundamental problem we have in dealing with global warming in that Western Civilization, and much of modern ecology, believes that nature, on its own, is unchanging. This is expressed in modern ecological science in many steady-state models and theories. As a result we have difficulties in dealing with environmental change. In my book, Discordant Harmonies: A New Ecology for the 21st Century, I write about this problem. Specifically, for thousands of years the belief in the great balance of nature has dominated secular and religious thoughts about the character of nature, nature’s effects on people, and the proper role of human beings within nature. It is so powerful that it still dominates in models used to manage endangered species and wild animals important commercially. For example, current work I am doing to help the International Whaling Commission reveals that their management of the bowhead whale used forecasting models that are steady-state. This talk can appeal to a wide audience, since I show imagines of paintings and talk about culture, and then discuss the implications within science.
Biosketch: See here.
Which fish where? The roles of phenotypic plasticity, abiotic and spatial factors in structuring freshwater fish assemblages (15th June 2007)
Dr. Pedro R. Peres-Neto, Departement des sciences biologiques
Université du Québec à Montréal (UQÀM)
Fish inhabiting freshwater systems provide excellent study systems for assessing the relative roles of various mechanisms that may be organizing community structure including regional as well as local processes. Connectivity and habitat geometry are often more severely limiting for fishes than for terrestrial species and thus dispersal generally plays as important a role as do local abiotic and biotic factors. The study of communities at multiple spatial scales is essential to evaluate the effects of positive and negative species interactions, and to establish comparative frameworks to evaluate the links between species and population-level traits (e.g., phenotypic plasticity, geographic range, life history traits) and habitat quality or extinction-colonization dynamics. For instance, one would like to answer questions like: which traits make a species susceptible to low or high rates of local extinction? Or which traits make species more or less responsive to environmental fluctuations? I will present and examine evidence for different structuring forces of stream and lake fish communities to assess: 1 – the roles of phenotypic plasticity and morphological integration in both tropical and temperate systems; 2 – how phenotypic plasticity react to water flow and swimming pressures and determine patterns of distribution and extinction-colonization dynamics; 3 – the differences in structuring factors between stream and lake fish assemblages. In addition, I introduce a quantitative framework for understanding the roles of local environment and spatial dynamics in structuring metacommunities.
Biosketch: My research interests lie at the interface of community and quantitative ecology, incorporating principles from a diverse suite of areas including spatial ecology, modeling, metacommunities, landscape ecology, ecomorphology and evolution. I work to determine the relative roles of multiple factors (phenotype, habitat choice, landscape structure, species interactions, phylogenetic history) influencing how regional pools of potential colonizer species are sorted into local communities. Examining the roles of multiple ecological factors in driving species distributions and community structure relies heavily on quantitative methods to detect statistical patterns in data. In this research line, I am interested in developing and assessing the performance of quantitative frameworks where different sources of information based on observational and experimental approaches can be embedded and analyzed jointly. See more here.
Latitudinal variation of freshwater diversity is not concordant across habitat types (27th April 2007)
Christian Hof, Museo Nacional de Ciencias Naturales in Madrid & Center for Macroecology, University of Copenhagen
The variation of species richness across latitude is one of the most fascinating phenomena in biodiversity research. However, there is ongoing debate on the underlying mechanisms determining the observed distribution patterns of biodiversity across our planet. Furthermore, there is a clear bias in macroecology and biogeography towards investigations on the marine and, particularly, on the terrestrial realm. Here, we analyze the variation in alpha- and beta-diversity across latitude for all European freshwater animals (> 14,000 species). Investigating the alpha-diversity of 25 pre-defined biogeographic freshwater regions, we found that species richness peaks in central Europe, which could not be explained by the effect of area. However, the relationship between species richness and latitude is not concordant across three fundamentally different habitat types: Groundwater and running water habitats show a monotonous decrease of species richness with increasing latitude, whereas standing water habitats exhibit a hump-shaped relationship. This difference calls for an explanation considering habitat conditions as well as traits of species adapted to these habitats. In general, standing water bodies are less persistent than running or groundwater habitats. Therefore species relying on standing water habitats evolved more efficient strategies for dispersal than species adapted to running or groundwater habitats – an idea which is based on the studies of Ignacio Ribera and colleagues on the water beetle fauna of Europe and the Iberian peninsula. This line of arguments is corroborated by our finding that species adapted to standing water bodies show lower levels of b-diversity among biogeographic regions. In our study on European and North American dragon- and damselflies, we could provide further evidence for this idea, showing that species of standing waters have larger and more northern ranges than species occurring in running water habitats.
Biosketch: See here.
Algunas reflexiones sobre tipología de modelos con motivo de nichos ecológicos (22nd March 2007)
Dr. Miguel Nakamura, Departamento de Probabilidad y Estadística, Centro de Investigación en Matemáticas, Guanajuato, México
Resumen: Se utilizará como plataforma el problema de predicción de nichos ecológicos—el cual parecería ser un problema canónico de clasificación binaria—con el objetivo de motivar consideraciones generales en torno a alcances y características de clases de técnicas de análisis. Se discutirán varios significados que puede tener el concepto de “modelo estadístico” para distintos gremios, haciendo referencia a Breiman (2001) (Statistical Science, 16, 199–226), quien ha descrito dos culturas generales llamadas “algorítmica” y de “modelación de datos”. Se discutirán ventajas y desventajas de cada escuela, y se ilustrarán algunas de las nociones que pueden surgir de un razonamiento de modelación de datos (Argáez, et al., 2005, Journal of Environmental and Ecological Statistics, 12, 27–44).
Biosketch: Miguel Nakamura es físico-matemático por el Instituto Politécnico Nacional de México. Obtuvo el grado de doctor en estadística matemática en la Universidad de Carolina del Norte en 1989. Trabaja en el departamento de probabilidad y estadística del Centro de Investigación en Matemáticas (CIMAT), en Guanajuato, México, desde 1990. Actualmente es coordinador de dicho departamento. Ha sido instrumental para establecer en el CIMAT un concepto de Laboratorio de Estadística, un canal de enlace entre investigación y usuarios académicos e usuarios científicos, sociales, y de la industria. Entre otras consecuencias, Miguel ha tenido diversas interacciones con biólogos y ecólogos, particularmente en temas de curvas de acumulación de especies y predicción de nichos ecológicos. Se interesa por la aplicación pertinente de la estadística en ciencia, en un ambiente interdisciplinario.
A database of Western Palearctic birds migrating within Africa to guide conservation decisions (20th February 2007)
Dr. Bruno Walther, Science Officer for bioGENESIS and bioDISCOVERY core projects DIVERSITAS, Paris
Bird migration is one of the most fascinating wonders of nature. For the over 300 species breeding in the Palaearctic region that migrate annually to their African wintering grounds, a database was created to map and monitor their distributions in Africa. The database now contains over 200000 records, and was used to improve the spatial and temporal knowledge of migration, especially of threatened species. Using the threatened Aquatic Warbler as an example, the combination of presence-only and presence-absence modeling techniques was used to model its African wintering range. Such modeled distributional maps were then used to analyse macro-ecological determinants of migrant species richness in sub-Saharan Africa, whereby geometric constraints, distance to breeding grounds and climatic variables explained most of the migrant species richness in sub-Saharan Africa. Finally, these distributions were used to select conservation priority areas for migrants.
Biosketch: See here.
