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ABSTRACT: Aim Studies investigating the theory of tropical refugia for vertebrates have pre-viously focused on a handful of species or a single taxonomic group. We sought to identify the potential location of cross-taxonomic refugia of African birds and mammals in the Last Glacial Maximum, and used historic climate data to hindcast the location of past ranges of species based on their current distributions.
Global Ecology and Biogeography 02/2013; 22(3):351-363. · 5.14 Impact Factor
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Bradford A Hawkins,
Fabio S Albuquerque,
Miguel B Araujo,
Jan Beck,
Luis Mauricio Bini,
Francisco J Cabrero-Sañudo,
Isabel Castro-Parga,
José Alexandre Felizola Diniz-Filho,
Dolores Ferrer-Castan,
Richard Field, [......],
Jorge M Lobo,
Daniel Montoya,
Juan Carlos Moreno,
Miguel A Olalla-Tárraga,
Juli G Pausas,
Hong Qian, Carsten Rahbek,
Miguel A Rodríguez,
Nathan J Sanders,
Paul Williams
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Ben G Holt,
Jean-Philippe Lessard,
Michael K Borregaard,
Susanne A Fritz,
Miguel B Araújo,
Dimitar Dimitrov,
Pierre-Henri Fabre,
Catherine H Graham,
Gary R Graves,
Knud A Jønsson,
David Nogués-Bravo,
Zhiheng Wang,
Robert J Whittaker,
Jon Fjeldså, Carsten Rahbek
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Ben G. Holt,
Jean-Philippe Lessard,
Michael K. Borregaard,
Susanne A. Fritz,
Miguel B. Araújo,
Dimitar Dimitrov,
Pierre-Henri Fabre,
Catherine H. Graham,
Gary R. Graves,
Knud A. Jønsson,
David Nogués-Bravo,
Zhiheng Wang,
Robert J. Whittaker,
Jon Fjeldså, Carsten Rahbek
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ABSTRACT: Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without
phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions
and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic
regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based
on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher
in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides
valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions
of the world.
Science 01/2013; 339(6115):74-78. · 31.20 Impact Factor
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Ben G Holt,
Jean-Philippe Lessard,
Michael K Borregaard,
Susanne A Fritz,
Miguel B Araújo,
Dimitar Dimitrov,
Pierre-Henri Fabre,
Catherine H Graham,
Gary R Graves,
Knud A Jønsson,
David Nogués-Bravo,
Zhiheng Wang,
Robert J Whittaker,
Jon Fjeldså, Carsten Rahbek
[show abstract]
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ABSTRACT: Modern attempts to produce biogeographic maps focus on the distribution of species and are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.
Science 12/2012; · 31.20 Impact Factor
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ABSTRACT: Avian faunas vary greatly among montane areas; those at high latitudes are biologically impoverished, whereas those of some low-latitude mountains are biologically very complex. Their high level of species richness is caused by the aggregation of many small-ranged species, which has been difficult to explain from purely macroecological models focusing on contemporary ecological processes. Because the individual mountain tracts harbor species that represent different evolutionary trajectories, it seems plausible to relate these species assemblages to high persistence (or absence of extinction) in addition to high levels of speciation. The distribution of small-ranged species is concentrated near tropical coasts, where moderation of the climate in topographically complex areas creates cloud forests and stable local conditions. The stability underpins specialization and resilience of local populations, and thereby the role of these places as cradles of biodiversity.
11/2012; 43:249-265.
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ABSTRACT: Resolving contingencies in community ecology requires comparative studies of local communities along broad-scale environmental gradients and in different biogeographic regions. However, comparisons of local ecological processes among regions require a synthetic understanding of how the species pool of potential community members influences the structure of ecological communities. Here, we outline an integrative approach for quantifying local ecological processes while explicitly accounting for species pool influences. Specifically, we highlight the utility of combining geographically replicated local studies, null models of community structure, and ecologically explicit definitions of the species pool as a means to compare predominant ecological processes among regions. By uniting concepts and tools from community ecology and macroecology, this approach might facilitate synthesis and resolve many perceived ecological contingencies.
Trends in Ecology & Evolution 08/2012; 27(11):600-7. · 15.75 Impact Factor
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ABSTRACT: The concept of species-level heritability is widely contested. Because it is most likely to apply to emergent, species-level traits, one of the central discussions has focused on the potential heritability of geographic range size. However, a central argument against range-size heritability has been that it is not compatible with the observed shape of present-day species range-size distributions (SRDs), a claim that has never been tested. To assess this claim, we used forward simulation of range-size evolution in clades with varying degrees of range-size heritability, and compared the output of three different models to the range-size distribution of the South American avifauna. Although there were differences among the models, a moderate-to-high degree of range-size heritability consistently leads to SRDs that were similar to empirical data. These results suggest that range-size heritability can generate realistic SRDs, and may play an important role in shaping observed patterns of range sizes.
Evolution 07/2012; 66(7):2216-26. · 5.15 Impact Factor
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Knud A Jønsson,
Pierre-Henri Fabre,
Susanne A Fritz,
Rampal S Etienne,
Robert E Ricklefs,
Tobias B Jørgensen,
Jon Fjeldså, Carsten Rahbek,
Per G P Ericson,
Friederike Woog,
Eric Pasquet,
Martin Irestedt
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ABSTRACT: Adaptive radiation is the rapid diversification of a single lineage into many species that inhabit a variety of environments or use a variety of resources and differ in traits required to exploit these. Why some lineages undergo adaptive radiation is not well-understood, but filling unoccupied ecological space appears to be a common feature. We construct a complete, dated, species-level phylogeny of the endemic Vangidae of Madagascar. This passerine bird radiation represents a classic, but poorly known, avian adaptive radiation. Our results reveal an initial rapid increase in evolutionary lineages and diversification in morphospace after colonizing Madagascar in the late Oligocene some 25 Mya. A subsequent key innovation involving unique bill morphology was associated with a second increase in diversification rates about 10 Mya. The volume of morphospace occupied by contemporary Madagascan vangas is in many aspects as large (shape variation)--or even larger (size variation)--as that of other better-known avian adaptive radiations, including the much younger Galapagos Darwin's finches and Hawaiian honeycreepers. Morphological space bears a close relationship to diet, substrate use, and foraging movements, and thus our results demonstrate the great extent of the evolutionary diversification of the Madagascan vangas.
Proceedings of the National Academy of Sciences 04/2012; 109(17):6620-5. · 9.68 Impact Factor
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ABSTRACT: Habitat persistence should influence dispersal ability, selecting for stronger dispersal in habitats of lower temporal stability. As standing (lentic) freshwater habitats are on average less persistent over time than running (lotic) habitats, lentic species should show higher dispersal abilities than lotic species. Assuming that climate is an important determinant of species distributions, we hypothesize that lentic species should have distributions that are closer to equilibrium with current climate, and should more rapidly track climatic changes. We tested these hypotheses using datasets from 1988 and 2006 containing all European dragon- and damselfly species. Bioclimatic envelope models showed that lentic species were closer to climatic equilibrium than lotic species. Furthermore, the models over-predicted lotic species ranges more strongly than lentic species ranges, indicating that lentic species track climatic changes more rapidly than lotic species. These results are consistent with the proposed hypothesis that habitat persistence affects the evolution of dispersal.
Biology letters 02/2012; 8(4):639-43. · 3.76 Impact Factor
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ABSTRACT: A common assumption in bioclimatic envelope modeling is that species distributions are in equilibrium with contemporary climate. A number of studies have measured departures from equilibrium in species distributions in particular regions, but such investigations were never carried out for a complete lineage across its entire distribution. We measure departures of equilibrium with contemporary climate for the distributions of the world amphibian species. Specifically, we fitted bioclimatic envelopes for 5544 species using three presence-only models. We then measured the proportion of the modeled envelope that is currently occupied by the species, as a metric of equilibrium of species distributions with climate. The assumption was that the greater the difference between modeled bioclimatic envelope and the occupied distribution, the greater the likelihood that species distribution would not be at equilibrium with contemporary climate. On average, amphibians occupied 30% to 57% of their potential distributions. Although patterns differed across regions, there were no significant differences among lineages. Species in the Neotropic, Afrotropics, Indo-Malay, and Palaearctic occupied a smaller proportion of their potential distributions than species in the Nearctic, Madagascar, and Australasia. We acknowledge that our models underestimate non equilibrium, and discuss potential reasons for the observed patterns. From a modeling perspective our results support the view that at global scale bioclimatic envelope models might perform similarly across lineages but differently across regions.
PLoS ONE 01/2012; 7(4):e34420. · 4.09 Impact Factor
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ABSTRACT: Africa is predicted to be highly vulnerable to 21st century climatic changes. Assessing the impacts of these changes on Africa's biodiversity is, however, plagued by uncertainties, and markedly different results can be obtained from alternative bioclimatic envelope models or future climate projections. Using an ensemble forecasting framework, we examine projections of future shifts in climatic suitability, and their methodological uncertainties, for over 2500 spe-cies of mammals, birds, amphibians and snakes in sub-Saharan Africa. To summarize a priori the variability in the ensemble of 17 general circulation models, we introduce a consensus methodology that combines co-varying models. Thus, we quantify and map the relative contribution to uncertainty of seven bioclimatic envelope models, three multi-model climate projections and three emissions scenarios, and explore the resulting variability in species turn-over estimates. We show that bioclimatic envelope models contribute most to variability, particularly in projected novel climatic conditions over Sahelian and southern Saharan Africa. To summarize agreements among projections from the bioclimatic envelope models we compare five consensus methodologies, which generally increase or retain projection accuracy and provide consistent estimates of species turnover. Variability from emissions scenarios increases towards late-century and affects southern regions of high species turnover centred in arid Namibia. Two-fold differences in median species turnover across the study area emerge among alternative climate projections and emissions scenarios. Our ensemble of projections underscores the potential bias when using a single algorithm or climate projection for Africa, and provides a cautious first approximation of the potential exposure of sub-Saharan African vertebrates to climatic changes. The future use and further development of bioclimatic envelope modelling will hinge on the interpretation of results in the light of methodological as well as biological uncertainties. Here, we provide a framework to address methodological uncertainties and contextualize results.
Global Change Biology 01/2012; 18:1253-1269. · 6.86 Impact Factor
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Ecography 01/2012; · 4.19 Impact Factor
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ABSTRACT: Viable populations of species occur in a given place if three conditions are met: the environment at the place is suitable; the species is able to colonize it; co-occurrence is possible despite or because of interactions with other species. Studies investigating the effects of climate change on species have mainly focused on measuring changes in climate suitability. Complex interactions among species have rarely been explored in such studies. We extend network theory to the analysis of complex patterns of co-occurrence among species. The framework is used to explore the robustness of networks under climate change. With our data, we show that networks describing the geographic pattern of co-occurrence among species display properties shared by other complex networks, namely that most species are poorly connected to other species in the network and only a few are highly connected. In our example, species more exposed to climate change tended to be poorly connected to other species within the network, while species more connected tended to be less exposed. Such high connectance would make the co-occurrence networks more robust to climate change. The proposed framework illustrates how network analysis could be used, together with co-occurrence data, to help addressing the potential consequences of species interactions in studies of climate change and biodiversity. However, more research is needed to test for links between co-occurrence and network interactions.
Ecography 11/2011; 34(6):897 - 908. · 4.19 Impact Factor
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ABSTRACT: Aim We evaluated the hypothesis that, given niche conservatism, relatedness of co-occurring hummingbird species of a given clade will increase at greater distances from the elevation where it originated. We also used prior knowledge of flight biomechanics and feeding specialization of hummingbird species (family Trochilidae) to evaluate which environmental variables were important predictors of changes in phylogenetic structure for each hummingbird clade.Location Ecuador.Methods We compiled species lists for 189 local hummingbird assemblages across major environmental gradients in Ecuador from a variety of published and non-published sources. For the entire family and each of the major hummingbird clades (hermits, emeralds, mangoes, coquettes and brilliants) we quantified the phylogenetic structure of each assemblage using the net relatedness index (NRI). This index calculates the standardized mean of all possible pairwise phylogenetic distances between co-occurring species. We related NRI for each clade to elevation, precipitation and vegetation-related variables using generalized additive models.Results Our findings support the prediction of an increase in the co-occurrence of close relatives away from the elevation of origin at the family level and for assemblages of mangoes and brilliants. The opposite pattern was found for assemblages of coquettes and emeralds. For the hermits, variation in phylogenetic structure was not explained by elevation. Clades with high levels of feeding specialization (hermits and brilliants) always included a vegetation-related variable as an important predictor of change in phylogenetic structure.Main conclusions We found no overall support for the conservatism and zone of origin hypotheses. Knowledge of each clade’s natural history proved useful for predicting which environmental variables correlated with phylogenetic structure of local assemblages. Clades with the same elevation of origin appear to have radiated along the elevational gradient in association with different environmental factors.
Journal of Biogeography 11/2011; 38(12):2350 - 2361. · 4.54 Impact Factor
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Anna-Sofie Stensgaard,
Jürg Utzinger,
Penelope Vounatsou,
Eveline Hürlimann,
Nadine Schur,
Christopher F.L. Saarnak,
Christopher Simoonga,
Patricia Mubita,
Narcis B. Kabatereine,
Louis-Albert Tchuem Tchuenté, Carsten Rahbek,
Thomas K. Kristensen
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ABSTRACT: The geographical ranges of most species, including many infectious disease agents and their vectors and intermediate hosts, are assumed to be constrained by climatic tolerances, mainly temperature. It has been suggested that global warming will cause an expansion of the areas potentially suitable for infectious disease transmission. However, the transmission of infectious diseases is governed by a myriad of ecological, economic, evolutionary and social factors. Hence, a deeper understanding of the total disease system (pathogens, vectors and hosts) and its drivers is important for predicting responses to climate change. Here, we combine a growing degree day model for Schistosoma mansoni with species distribution models for the intermediate host snail (Biomphalaria spp.) to investigate large-scale environmental determinants of the distribution of the African S. mansoni-Biomphalaria system and potential impacts of climatic changes. Snail species distribution models included several combinations of climatic and habitat-related predictors; the latter divided into “natural” and “human-impacted” habitat variables to measure anthropogenic influence. The predictive performance of the combined snail–parasite model was evaluated against a comprehensive compilation of historical S. mansoni parasitological survey records, and then examined for two climate change scenarios of increasing severity for 2080. Future projections indicate that while the potential S. mansoni transmission area expands, the snail ranges are more likely to contract and/or move into cooler areas in the south and east. Importantly, we also note that even though climate per se matters, the impact of humans on habitat play a crucial role in determining the distribution of the intermediate host snails in Africa. Thus, a future contraction in the geographical range size of the intermediate host snails caused by climatic changes does not necessarily translate into a decrease or zero-sum change in human schistosomiasis prevalence.Graphical abstractClimate change is predicted to cause a shift and net contraction in the geographical distribution of the Schistosoma mansoni-Biomphalaria system in Africa. However, species distribution models reveal that natural and human-impacted habitat types play a major role in determining the current distribution of the intermediate host snails. Thus, the future geospatial transmission patterns of this parasite–snail system are likely to be shaped by an interaction between climate per se and other human-induced environmental changes.Highlights► We examine the distributions of S. mansoni intermediate host snails in Africa. ► Species distribution models are combined with parasite growing degree day models. ► Human impacted habitat factors are important determinants of snail distributions. ► Climate change is predicted to cause a range contraction for Biomphalaria snails. ► New areas might become suitable for parasite transmission.
Acta tropica 11/2011; · 2.22 Impact Factor
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Science 11/2011; 334(6059):1070-1. · 31.20 Impact Factor
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ABSTRACT: Amphibian population declines far exceed those of other vertebrate groups, with 30% of all species listed as threatened by the International Union for Conservation of Nature. The causes of these declines are a matter of continued research, but probably include climate change, land-use change and spread of the pathogenic fungal disease chytridiomycosis. Here we assess the spatial distribution and interactions of these primary threats in relation to the global distribution of amphibian species. We show that the greatest proportions of species negatively affected by climate change are projected to be found in Africa, parts of northern South America and the Andes. Regions with the highest projected impact of land-use and climate change coincide, but there is little spatial overlap with regions highly threatened by the fungal disease. Overall, the areas harbouring the richest amphibian faunas are disproportionately more affected by one or multiple threat factors than areas with low richness. Amphibian declines are likely to accelerate in the twenty-first century, because multiple drivers of extinction could jeopardize their populations more than previous, mono-causal, assessments have suggested.
Nature 11/2011; 480(7378):516-9. · 36.28 Impact Factor
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Eline D Lorenzen,
David Nogués-Bravo,
Ludovic Orlando,
Jaco Weinstock,
Jonas Binladen,
Katharine A Marske,
Andrew Ugan,
Michael K Borregaard,
M Thomas P Gilbert,
Rasmus Nielsen, [......],
Marc A Suchard,
Alexei Tikhonov,
Rane Willerslev,
Robert K Wayne,
Alan Cooper,
Michael Hofreiter,
Andrei Sher,
Beth Shapiro, Carsten Rahbek,
Eske Willerslev
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ABSTRACT: Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.
Nature 11/2011; 479(7373):359-64. · 36.28 Impact Factor
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ABSTRACT: The small size of the billions of migrating songbirds commuting between temperate breeding sites and the tropics has long prevented the study of the largest part of their annual cycle outside the breeding grounds. Using light-level loggers (geolocators), we recorded the entire annual migratory cycle of the red-backed shrike Lanius collurio, a trans-equatorial Eurasian-African passerine migrant. We tested differences between autumn and spring migration for nine individuals. Duration of migration between breeding and winter sites was significantly longer in autumn (average 96 days) when compared with spring (63 days). This difference was explained by much longer staging periods during autumn (71 days) than spring (9 days). Between staging periods, the birds travelled faster during autumn (356 km d(-1)) than during spring (233 km d(-1)). All birds made a protracted stop (53 days) in Sahelian sub-Sahara on southbound migration. The birds performed a distinct loop migration (22 000 km) where spring distance, including a detour across the Arabian Peninsula, exceeded the autumn distance by 22 per cent. Geographical scatter between routes was particularly narrow in spring, with navigational convergence towards the crossing point from Africa to the Arabian Peninsula. Temporal variation between individuals was relatively constant, while different individuals tended to be consistently early or late at different departure/arrival occasions during the annual cycle. These results demonstrate the existence of fundamentally different spatio-temporal migration strategies used by the birds during autumn and spring migration, and that songbirds may rely on distinct staging areas for completion of their annual cycle, suggesting more sophisticated endogenous control mechanisms than merely clock-and-compass guidance among terrestrial solitary migrants. After a century with metal-ringing, year-round tracking of long-distance migratory songbirds promises further insights into bird migration.
Proceedings of the Royal Society B: Biological Sciences 09/2011; 279(1730):1008-16. · 5.41 Impact Factor
