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Lefevre S.,University of Oslo | Mckenzie D.J.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Nilsson G.E.,University of Oslo
Global Change Biology | Year: 2017

Some recent modelling papers projecting smaller fish sizes and catches in a warmer future are based on erroneous assumptions regarding (i) the scaling of gills with body mass and (ii) the energetic cost of 'maintenance'. Assumption (i) posits that insurmountable geometric constraints prevent respiratory surface areas from growing as fast as body volume. It is argued that these constraints explain allometric scaling of energy metabolism, whereby larger fishes have relatively lower mass-specific metabolic rates. Assumption (ii) concludes that when fishes reach a certain size, basal oxygen demands will not be met, because of assumption (i). We here demonstrate unequivocally, by applying accepted physiological principles with reference to the existing literature, that these assumptions are not valid. Gills are folded surfaces, where the scaling of surface area to volume is not constrained by spherical geometry. The gill surface area can, in fact, increase linearly in proportion to gill volume and body mass. We cite the large body of evidence demonstrating that respiratory surface areas in fishes reflect metabolic needs, not vice versa, which explains the large interspecific variation in scaling of gill surface areas. Finally, we point out that future studies basing their predictions on models should incorporate factors for scaling of metabolic rate and for temperature effects on metabolism, which agree with measured values, and should account for interspecific variation in scaling and temperature effects. It is possible that some fishes will become smaller in the future, but to make reliable predictions the underlying mechanisms need to be identified and sought elsewhere than in geometric constraints on gill surface area. Furthermore, to ensure that useful information is conveyed to the public and policymakers about the possible effects of climate change, it is necessary to improve communication and congruity between fish physiologists and fisheries scientists. © 2017 John Wiley & Sons Ltd.


Lefevre S.,University of Oslo | Bayley M.,University of Aarhus | Mckenzie D.J.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Mckenzie D.J.,Federal University of São Carlos
Journal of Fish Biology | Year: 2016

Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2016 The Fisheries Society of the British Isles.


Pearson R.G.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Phillips S.J.,AT and T Labs Research | Loranty M.M.,Woods Hole Oceanographic Institution | Loranty M.M.,Colgate University | And 6 more authors.
Nature Climate Change | Year: 2013

Climate warming has led to changes in the composition, density and distribution of Arctic vegetation in recent decades. These changes cause multiple opposing feedbacks between the biosphere and atmosphere, the relative magnitudes of which will have globally significant consequences but are unknown at a pan-Arctic scale. The precise nature of Arctic vegetation change under future warming will strongly influence climate feedbacks, yet Earth system modelling studies have so far assumed arbitrary increases in shrubs (for example, +20%; refs,), highlighting the need for predictions of future vegetation distribution shifts. Here we show, using climate scenarios for the 2050s and models that utilize statistical associations between vegetation and climate, the potential for extremely widespread redistribution of vegetation across the Arctic. We predict that at least half of vegetated areas will shift to a different physiognomic class, and woody cover will increase by as much as 52%. By incorporating observed relationships between vegetation and albedo, evapotranspiration and biomass, we show that vegetation distribution shifts will result in an overall positive feedback to climate that is likely to cause greater warming than has previously been predicted. Such extensive changes to Arctic vegetation will have implications for climate, wildlife and ecosystem services. © 2013 Macmillan Publishers Limited. All rights reserved.


Douglas L.R.,University of the West Indies | Douglas L.R.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Alie K.,Wildlife Trade Program
Biological Conservation | Year: 2014

The relationship between natural resources and conflict is well documented, except for wildlife. We discuss the role that wildlife can play in national and international security interests, including wildlife's role in financing the activities of belligerent groups and catalyzing social conflict. We argue that, similar to the findings for other high-value natural resources, wildlife can have a powerful influence on violent conflicts and security interests, particularly in developing and weak states, where the earth's biological resources are disproportionately found. We suggest that recognizing this relationship is important because it illuminates the gravity of the threat facing several charismatic species. The association also illuminates a neglected link between wildlife conservation and high-priority security and development policy concerns. We advocate that documenting and deconstructing the relationship between the wildlife trade and international crime, armed conflict, security, and development concerns within the context of our knowledge of other high-value natural resources has policy and management implications of great important in conservation practice. © 2014 Elsevier Ltd.


Nichols E.,University of Sao Paulo | Nichols E.,Lancaster University | Gomez A.,CNRS Center for Marine Biodiversity, Exploitation and Conservation
Parasitology | Year: 2014

Dung beetles are detrivorous insects that feed on and reproduce in the fecal material of vertebrates. This dependency on vertebrate feces implies frequent contact between dung beetles and parasitic helminths with a fecal component to their life-cycle. Interactions between dung beetles and helminths carry both positive and negative consequences for successful parasite transmission, however to date there has been no systematic review of dung beetle-helminth interactions, their epidemiological importance, or their underlying mechanisms. Here we review the observational evidence of beetle biodiversity-helminth transmission relationships, propose five mechanisms by which dung beetles influence helminth survival and transmission, and highlight areas for future research. Efforts to understand how anthropogenic impacts on biodiversity may influence parasite transmission must include the development of detailed, mechanistic understanding of the multiple interactions between free-living and parasitic species within ecological communities. The dung beetle-helminth system may be a promising future model system with which to understand these complex relationships. © 2014 Cambridge University Press.


Andersen M.J.,University of Kansas | Oliveros C.H.,University of Kansas | Filardi C.E.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Moyle R.G.,University of Kansas
Auk | Year: 2013

We reconstructed the phylogeographic relationships of the Variable Dwarf-Kingfisher (Ceyx lepidus) using DNA sequence data. Maximum likelihood and Bayesian analysis methods were used to reconstruct trees from a multilocus data set of all 15 named subspecies of the Ceyx lepidus species complex. The concatenated data-set length was 2,471 base pairs and included two mitochondrial genes and two noncoding nuclear introns. Support for the monophyly of C. lepidus was equivocal. We instead found support for a clade including all C. lepidus subspecies plus two endemic Philippine taxa: C. argentatus and C. cyanopectus. Relationships among subspecific taxa were not well resolved, and many nodes were collapsed into polytomies suggesting a rapid and widespread colonization. In situ diversification likely played a role in generating current diversity within four archipelagos: the Philippines, Malukus, Bismarcks, and Solomons. Some biogeographic patterns recovered for the Solomon Islands taxa match those seen in other bird species, such as the close relationship of taxa on Bougainville, Choiseul, and Isabel. By contrast, the sister relationship between populations on Guadalcanal and the New Georgia Group is novel. We discuss species limits and make taxonomic recommendations to treat all 15 subspecies of C. lepidus as species. Copyright © 2013 by The American Ornithologists' Union.


Bain R.H.,Canadian Museum of Nature | Hurley M.M.,CNRS Center for Marine Biodiversity, Exploitation and Conservation
Bulletin of the American Museum of Natural History | Year: 2011

Indochina (Laos, Cambodia, and Vietnam) houses over 600 species of amphibians and reptiles, roughly a quarter of which has been described within the last 15 years. Herein, we undertake the first biogeographic synthesis of the regional herpetofauna since the first half of the 20th century. We review the literature to measure and map species richness and endemism, the contributions of regional faunas, and ecological characteristics of Indochina's amphibians (Anura, Caudata), and reptiles (Serpentes, Sauria, Testudines, Crocodylia). Dividing Indochina into 19 subregions defined by topography and geology, we estimate the similarity among the regional faunas and appraise the effects of area and survey effort on these comparative analyses. Variation in species composition is broadly correlated with topography, habitat complexity, and proximity to regions outside Indochina. Indochina's herpetofauna is dominated (in decreasing order) by endemic species, widely distributed species, a South China fauna, and a biota centered in Thailand and Myanmar. Species richness is highest in amphibians and snakes, and peaks in upland forests. Endemism, highest among amphibians and lizards, also peaks in forests of the region's northern uplands and Annamite Range. Endemic species occupy a narrower range of habitats than nonendemics. Patterns of richness and endemism are partially explained by ecological constraints: amphibians and lizards are more restricted to forests than snakes, turtles, and crocodiles; amphibians are more restricted to uplands, turtles to lowlands. We also assess biogeography in the context of Indochina's geology, climate, and land cover. In northern Indochina, the Red River either acts as or coincides with an apparent dispersal barrier. Herpetofauna in northeastern upland areas are closely allied with fauna of southeastern China. In southern Indochina there is little evidence that the Mekong River represents a biogeographic barrier to the regional herpetofauna. The Annamite Range is composed of at least three distinct units and its elevated species richness and endemism are also noted in adjacent lowlands. Contribution of subtropical biota to Indochina's fauna is significantly greater than that of tropical biota and there is little other evidence for intermixing at intermediate latitudes. Our results have implications for biogeography and conservation efforts, although they must be viewed in the context of rapidly evolving systematic knowledge of the region's amphibians and reptiles. Future survey efforts, and the phylogenetic analyses that come from them, are essential for supporting regional conservation efforts, as they will better resolve the known patterns of amphibian and reptile richness and endemism. © 2011 American Museum of Natural History.


Gibbs J.P.,New York University | Sterling E.J.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Zabala F.J.,Charles Darwin Research Station
Biotropica | Year: 2010

Giant tortoises were once a megafaunal element widespread in tropical and subtropical ecosystems. The role of giant tortoises as herbivores and seed dispersers, however, is poorly known. We evaluated tortoise impacts on Opuntia cactus (Cactaceae) in the Galápagos Islands, one of the last areas where giant tortoises remain extant, where the cactus is a keystone resource for many animals. We contrasted cactus populations immediately inside and outside natural habitats where tortoises had been held captive for several decades. Through browsing primarily and trampling secondarily tortoises strongly reduced densities of small (0.5-1.5 m high) cacti, especially near adult cacti, and thereby reduced densities of cacti in larger size classes. Tortoises also caused a shift from vegetative to sexual modes of reproduction in cacti. We conclude that giant tortoises promote a sparse and scattered distribution in Opuntia cactus and its associated biota in the Galápagos Islands. 2009 The Author(s). Journal compilation © 2009 by The Association for Tropical Biology and Conservation.


Nichols E.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Nichols E.,Columbia University | Gomez A.,CNRS Center for Marine Biodiversity, Exploitation and Conservation
Biological Conservation | Year: 2011

Formal training in conservation biology education is an important component of the suite of solutions to current environmental problems. As conservation biology textbooks underpin many conservation education programs at both undergraduate and graduate levels, the portrayal of conservation issues and coverage of specific biotic groups plays a potentially important role in guiding the training of the next generation of conservation professionals. Parasites represent the majority of species diversity on earth, play critical roles in ecology and evolution, and are often at higher risk of decline and extinction than their free-living counterparts. Yet parasites continue to receive scant attention from conservation scientists and educators. We searched the index of 77 English language conservation biology textbooks for parasite or pathogen related content, published between 1970 and 2009. When present, we categorized a textbook's parasite content as positive, neutral or negative with respect to the author's portrayal of parasite biodiversity. The vast majority (72%) of conservation textbooks either portray parasites uniquely as threats to conservation goals established for free-living species or do not mention parasites at all. While no single textbook can be expected to provide extensive treatment of conservation-related topics across all biological groups, we outline three reasons why parasites should feature more prominently in formal conservation education, and suggest several ways in which greater incorporation of these parasite topics could strengthen the teaching and practice of conservation biology. © 2010.


Sterling E.J.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Gomez A.,CNRS Center for Marine Biodiversity, Exploitation and Conservation | Porzecanski A.L.,CNRS Center for Marine Biodiversity, Exploitation and Conservation
BioEssays | Year: 2010

Historically, views and measurements of biodiversity have had a narrow focus, for instance, characterizing the attributes of observable patterns but affording less attention to processes. Here, we explore the question: how does a systems thinking view - one where the world is seen as elements and processes that connect and interact in dynamic ways to form a whole - affect the way we understand biodiversity and practice conservation? We answer this question by illustrating the systemic properties of biodiversity at multiple levels, and show that biodiversity is a collection of dynamic systems linking seemingly disparate biological and cultural components and requiring an understanding of the system as a whole. We conclude that systems thinking calls traditional views of species, ecosystem function, and human relationships with the rest of biodiversity into question. Finally, we suggest some of the ways in which this view can impact the science and practice of conservation, particularly through affecting our conservation targets and strategies. © 2010 WILEY Periodicals, Inc.

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