Macroecology

Evolution: opportunity versus innovation

by Andy Purvis

Metabolic Theory of Ecology and diversity of continental zooplankton in Brazil

by Fernanda Cassemiro

Local‐to continental‐scale variation in the richness and composition of an aquatic food web

by Hannah Buckley

Latitudinal gradients in taxonomic overdescription rate affect macroecological inferences using species list data

by Owen Jones

Published in Ecography 2011

Species lists for particular geographic areas are often used in macroecology and conservation; for example, they have... more Species lists for particular geographic areas are often used in macroecology and conservation; for example, they have been used to identify hotspots of biological diversity, and for the study of latitudinal species diversity gradients. However, there is uncertainty over the accuracy of species lists due to undiscovered species and synonymy of described species. This paper concentrates on taxonomic overdescription caused by the latter. Where bias in the amount of taxonomic overdescription occurs along a variable of interest (e.g. latitude or body size), inferences from macroecological studies may be affected. This form of taxonomic overdescription is likely to be most pronounced in speciose groups, where many species have relatively small geographic range sizes and have low numerical abundance. A good example of such a group is the wasp family Ichneumonidae. We first use taxonomic and region-specific species list data for the Ichneumonidae to estimate the probability of species validity. Then we use this estimated probability to statistically correct the region's species richness estimate using a Monte Carlo simulation approach, and examine the effect the correction has on three major macroecological patterns: the relative species richness of geographic regions, latitudinal species richness pattern, and body size. Our results indicate that although there is significant geographic variation in overdescription, the bias is not sufficient to qualitatively alter broad-scale macroecological conclusions such as hotspot identity, and the qualitative global patterns of diversity and mean body size.

The terminology of metacommunity ecology

by Tadeu Siqueira

Article co-authored with Amanda K. Winegardner, Brittany K. Jones, Ingrid S.Y. Ng and Karl Cottenie. Published in Trends in Ecology & Evolution, 27, 253–254.

Domesticated crop richness in human subsistence cultivation systems: a test of macroecological and economic determinants

by Jacob Freeman

Aim:  To describe patterns of crop richness at a global scale and investigate the potential influence of energy,... more Aim:  To describe patterns of crop richness at a global scale and investigate the potential influence of energy, water, habitat heterogeneity, area and economic commitment to agricultural practices on patterns of crop species richness.

Location:  World-wide.

Methods:  Ethnographic literature for 86 subsistence-oriented societies was surveyed; 55 of these societies grow crops and 31 do not. These 86 societies occupy the range of latitudes at which subsistence-oriented groups manage domesticated plant species. The number of domesticated plants that each society cultivates is reported. Regression analyses were conducted to evaluate predictions for relationships between crop richness, energy, area, habitat heterogeneity, commitment to cultivation and species taxonomic descriptions.

Results:  Crop richness is positively and significantly related to energy availability and commitment to cultivation. The warmer the environment in which cultivators live, the more crop species cultivators grow. The more subsistence farmers commit to cultivation, the more crop species subsistence farmers grow. Above a threshold of 500 m in elevation range, crop richness is positively related to topographic heterogeneity. Mean annual rainfall, elevation, area, commitment to domesticated animals and exchange are not significantly related to crop richness.

Main conclusions:  Crop richness in subsistence-oriented farming systems is conditioned by energy availability via the physiological tolerances of crop species. Crop richness is secondarily conditioned by topographic heterogeneity, which may serve as an estimate of spatial climatic heterogeneity. Where energy availability is a relatively weak constraint on crop production, commitment to cultivation for subsistence strongly conditions how much effort producers invest in diversifying their crop base. It is postulated that tolerance to freezing temperatures limits the ranges of domesticated plant species. This range limitation might be the result of niche conservation among domesticated crop species and a legacy of greater rates of speciation and lower rates of extinction among ‘free living’ species in tropical settings.

Rise of dinosaurs reveals major body-size transitions are driven by passive processes of trait evolution

by Roland Sookias

A teoria metabólica da ecologia eo padrão espacial de riqueza de espécies de anfíbios do Novo Mundo

by Fernanda Cassemiro

Abundance distributions imply elevated complexity of post-Paleozoic marine ecosystems

by Matthew Kosnik

Persistent predator–prey dynamics revealed by mass extinction

by Lauren Sallan

Mixed-feeding and the diversication of ruminants through the Tertiary

by Juan L. Cantalapiedra

Co-authored with FitzJohn RG, Hernández Fernández M, DeMiguel D, Azanza B, Morales J, Mooers AØ

BMC Evol Biol. (submitted)

Background. Global abiotic change and ecological flexibility are two major factors influencing rates of speciation and... more Background. Global abiotic change and ecological flexibility are two major factors influencing rates of speciation and extinction across clades. The evolution of feeding styles is though to be key in the explosive radiation of ruminants. Classic scenarios depict browsing as the ancestral state with gradual evolution towards mixed-feeding and grazer concomitant with increasing aridity and subsequent expansion of open habitats during the Neogene.  However new insights have challenged this view, suggesting mixed-feeding ancestors for several of ruminant families. Here, we explored which the most likely scenarios explaining the evolutionary transitions among diets and ask whether ruminant lineages with different feeding styles (browsing, grazing and mixed feeding) underwent differential rates of diversification and how this might have been affected by global temperature regimes. We use new multi-state speciation and extinction (MuSSE) models on the supertree of the group, an accurate synthesis of dietary categories of all 197 extant species of ruminants, and a precise record of global Tertiary climate.
Results. The best model of trait change was one positing transitions from browsers to grazers via mixed feeding, with appreciable rates of transition to and from grazing and mixed feeding. MuSSE inferred higher speciation rates in mixed-feeding and grazing lineages than in browsers. The inclusion of Tertiary global temperature data did not significantly improve the model fits. A browser ancestor was reconstructed for Giraffidae, Moschidae and Tragulidae, while a mixed feeding ancestor is inferred for Bovidae. For all ruminants and for Cervidae, both browsing and mixed feeding are possible ancestral states, though browsing is preferred for ruminants, and mixed feeding for the Cervidae.
Conclusions. Our results are consistent with dietary flexibility rather than diet itself being related to the diversification of ruminants in the Neogene, and with climate having differential repercussions on physical habitat change and diet at regional rather than at global scale.

Rivadeneira, M.M., P. Hernáez, J.A. Baeza, S. Boltaña, M. Cifuentes, C. Correa, A. Cuevas, E. del Valle, I. Hinojosa, N. Ulrich, N. Valdivia, N. Vásquez, A. Zander, and M. Thiel. 2010. Testing the abundant-center hypothesis using intertidal porcelain crabs along the Chilean coast: linking abundance and distribution to life history variation. Journal of Biogeography 37(3): 486–498.

by Antonio Baeza

Deep-time analysis of a meta-community dynamics: The case study of the Paleogene mammals from the Quercy and Limagne area (Massif Central, France)

by Serge Legendre

ESCARGUEL, G. and LEGENDRE, S. 2006. Deep-time analysis of a meta-community dynamics: The case study of the Paleogene mammals from the Quercy and Limagne area (Massif Central, France). Strata, Sér. 1, 13, 245-273.

This study presents some preliminary results about the long-term evolutionary dynamics of the Paleogene mammalian... more This study presents some preliminary results about the long-term evolutionary dynamics of the Paleogene mammalian meta-community of the Quercy and Limagne area (Massif Central, France). We apply various quantitative analytical tools – computation of taxonomical evolutionary rates; statistical testing and comparison of prenascence and survivorship poly-cohort curves; analysis of within-group diversification – to a dataset including 331 mammalian phyletic lineages recorded within 170 published local faunas and 17 biochronological units in the Late Eocene-Early Miocene time span (MP16-MN2a). Main results are: three eutherian guilds (Ferae, Glires and Ungulata) are characterized by distinct coefficients of temporal scaling and intrinsic rates of phyletic richness evolution; the Eocene/Oligocene and Early/Late Oligocene limits are critical times in the origination/immigration and extinction/emigration dynamics of the meta-community; from the "Grande Coupure de Stehlin" onward, the meta-community shows a highly structured evolutionary dynamic driven by a regular alternation of extinction/emigration and origination/immigration phases. These first results indicate that the analyzed data set represents a rather unique opportunity to test several currently debated macroecological hypotheses.

Unearthing deep-time biodiversity changes: The Palaeogene mammalian metacommunity of the Quercy and Limagne area (Massif Central, France)

by Serge Legendre

ESCARGUEL, G., LEGENDRE, S. and SIGÉ, B. 2008. Unearthing deep-time biodiversity changes: The Palaeogene mammalian metacommunity of the Quercy and Limagne area (Massif Central, France). Comptes Rendus Geoscience, 340, 602-614.

The long-term changes of the mammalian diversity of the Quercy and Limagne area (Massif Central, France) is... more The long-term changes of the mammalian diversity of the Quercy and Limagne area (Massif Central, France) is quantitatively investigated through a ~16-Myr time span running from the late Middle Eocene (~38 Myr) to the Early Miocene (~22 Myr). Within the specific context of ecosystem response to extreme climatic events, the goal of such a deep-time approach to local community and regional metacommunity evolution is to give time-scaled reference series with which extant changes can be objectively compared. The results indicate that local and regional ecological integration levels show very distinct evolutionary dynamics, involving at least partially independent sets of controlling parameters; those driving the metacommunity still remain largely to be better understood. Clearly, the analyzed data set constitutes a rather unique deep-time key into several major current macroecological debates

Biodiversity is not (and never has been) a bed of roses!

by Serge Legendre

ESCARGUEL, G., FARA, E., BRAYARD, A. and LEGENDRE, S. 2011. Biodiversity is not (and never has been) a bed of roses! Comptes Rendus Biologies, 334, 351-359.

Over the last decades, the critical study of fossil diversity has led to significant advances in the knowledge of... more Over the last decades, the critical study of fossil diversity has led to significant advances in the knowledge of global macroevolutionary patterns of biodiversity. The deep-time history of life on Earth results from background originations and extinctions defining a steady-state, nonstationary equilibrium occasionally perturbed by biotic crises and “explosive” diversifications. More recently, a macroecological approach to the large-scale distribution of extant biodiversity offered new, stimulating perspectives on old theoretical questions and current practical problems in conservation biology. However, time and space are practically distinct, but functionally related dimensions of ecological systems. This calls for a spatially-integrated study of biodiversity dynamics at an evolutionary timescale. Indeed, the biosphere is a complex adaptive system whose study cannot be arbitrarily reduced to any single spatial- and/or temporal-scale level of resolution without a loss of content. From such an integrated perspective, a simple fact emerges: in a physically heterogeneous and ever-changing world, spatiotemporal variations in biodiversity are the rule–not the exception.

Small mammal (rodents and lagomorphs) European biogeography from the Late Oligocene to the mid Pliocene

by Serge Legendre

MARIDET, O., ESCARGUEL, G., COSTEUR, L., MEIN, P., HUGUENEY, M. and LEGENDRE, S. 2007. Small mammal (rodents and lagomorphs) European biogeography from the Late Oligocene to the mid Pliocene. Global Ecology and Biogeography, 16, 529-544.

Aim: To analyse the fossil species assemblages of rodents and lagomorphs from the European Neogene in order to assess... more Aim: To analyse the fossil species assemblages of rodents and lagomorphs from the European Neogene in order to assess what factors control small mammal biogeography at a deep-time evolutionary time-scale.
Location: Western Europe: 626 fossil-bearing localities located within 31 regions and distributed among 18 successive biochronological units ranging from c. 27 Ma (million years ago; Late Oligocene) to c. 3 Ma (mid Pliocene).
Methods: Taxonomically homogenized pooled regional assemblages are compared using the Raup and Crick index of faunal similarity; then, the inferred similarity matrices are visualized as neighbour-joining trees and by projecting the statistically significant interregional similarities and dissimilarities onto palaeogeographical maps. The inferred biogeographical patterns are analysed and discussed in the light of known palaeogeographical and palaeoclimatic events.
Results: Successive time intervals with distinct biogeographical contexts are identified. Prior to c. 18 Ma (Late Oligocene and Early Miocene), a relative faunal homogeneity (high interregional connectivity) is observed all over Europe, a time when major geographical barriers and a weak climatic gradient are known. Then, from the beginning of the Middle Miocene onwards, the biogeography is marked by a significant decrease in interregional faunal affinities which matches a drastic global climatic degradation and leads, in the Late Miocene (c. 11 Ma), to a marked latitudinal pattern of small mammal distribution. In spite of a short rehomogenization around the Miocene/Pliocene boundary (6–4 Ma), the biogeography of small mammals in the mid Pliocene (c. 3 Ma) finally closely reflects the extant situation.
Main conclusions: The resulting biogeographical evolutionary scheme indicates that the extant endemic situation has deep historical roots corresponding to global tectonic and climatic events acting as primary drivers of long-term changes. The correlation of biogeographical events with climatic changes emphasizes the prevalent role of the climate over geography in generating heterogeneous biogeographical patterns at the continental scale.

Multiple environmental determinants of regional species richness and effects of geographic range size

by J. Sebastian Tello

Tello, J. S. and Stevens, R. D. 2010. Ecography 33: 796-808

Understanding patterns of species richness at broad geographic extents remains one of the most challenging yet... more Understanding patterns of species richness at broad geographic extents remains one of the most challenging yet necessary scientific goals of our time. Many hypotheses have been proposed to account for spatial variation in species richness; among them, environmental determinants have played a central role. In this study, we use data on regional bat species richness in the New World to study redundancy and complementarity of three environmental hypotheses: energy, heterogeneity and seasonality. We accomplish this by partitioning variation in species richness among components associated with unique and combined effects of variables from each hypotheses, and by partitioning the overall richness gradient into gradients of species with varying breadths of geographic distribution.
These three environmental hypotheses explain most variation in the species richness gradient of all bats, but do not account for all positive spatial autocorrelation at short distances. Although environmental predictors are highly redundant, energy and seasonality explain different and complementary fractions of variation in species richness of all bats. On the other hand, heterogeneity variables contribute little to explain this gradient. However, results change dramatically when richness is estimated for groups of species with different sizes of geographic distribution. First, the amount of variation explained by environment decreases with a decrease in range size; this suggests that richness gradients of small-ranged species can not be explained as easily as those of broadly distributed species, as has been implied by analyses that do not consider differences in range size among species. Second, the relative contribution of environmental predictors to explained variation also changes with change in range size. Seasonality and energy are good predictors of species with broad distributions, but they loose almost all explanatory power for richness of species with small ranges. In contrast, heterogeneity, which is a relatively poor predictor of richness of species with large ranges, becomes the main predictor of richness gradients of species with restricted distributions. This suggests that range size is a different dimension on which heterogeneity and other environmental characteristics are complementary to each other. Our results suggest that determinants of species richness gradients might be complex, or at least more complex than many studies have previously suggested.

Murciélagos, características ambientales y efectos de mitad de dominio (Bats, environmental characteristics and mid-domain effects)

by J. Sebastian Tello

Tello, J. S. and Stevens, R. D. Accepted. In Tirira, D., Burneo, S. and Boada, C. (eds.). Investigación y conservación de los murciélagos del Ecuador.

Resumen
Los procesos que dan origen a los gradientes de diversidad han sido el foco de estudio de ecólogos y... more Resumen
Los procesos que dan origen a los gradientes de diversidad han sido el foco de estudio de ecólogos y biogeógrafos por más de dos siglos. Durante estos 200 años de investigación, un gran número de hipótesis han sido propuestas para explicar patrones de riqueza de especies a grandes escalas. Entre estas, la idea de que características ambientales controlan la variación en riqueza de especies es una de las más antiguas y mejor investigadas. Por el otro lado, una de las hipótesis más nuevas y controversiales es la de efectos de mitad de dominio; esta hipótesis sugiere que los gradientes de diversidad son simplemente una consecuencia de la distribución aleatoria de especies, siempre y cuando estas distribuciones estén bajo ciertas limitaciones geométricas. En este estudio investigamos las causas del gradiente de diversidad de murciélagos en el Nuevo Mundo. Cuantificamos la variación en riqueza de especies que puede ser atribuida a efectos de mitad de dominio, y determinamos si variables ambientales pueden explicar variación en riqueza incluso después de tomar en cuenta los efectos de mitad de dominio. Para esto, construimos 1000 gradientes de diversidad esperados bajo las condiciones de efectos de mitad de dominio, y comparamos estos gradientes esperados con el gradiente empírico. Estos análisis fueron conducidos separadamente para tres grupos de murciélagos: Noctilionoidea, Molossidae y Vespertilionidae. Nuestros resultados sugieren que efectos de mitad de dominio pueden ser importantes para los gradientes de diversidad de Noctilionoidea y Molossidae, pero no para Vespertilionidae. Por el otro lado, los gradientes ambientales son importantes independientemente del grupo de especies considerado. Sin embargo, la importancia de energía versus heterogeneidad podrían depender del modo en que los gradientes ambientales afectan a los patrones de riqueza de especies: si las variables ambientales afectan directamente al número de especies que coexisten, entonces es claro que energía es más importante que heterogeneidad; pero si las variables ambientales modifican el patrón de riqueza esperado por efectos de mitad de dominio, entonces ambas características ambientales parecen ser igualmente importantes.


Abstract
Processes that give rise to diversity gradients have been the focus of study by ecologists and biogeographers for more than two centuries. During these two hundred years of research, a large number of hypotheses have been proposed to explain patterns of variation in species richness at broad scales. Among these, the idea that environmental characteristics control variation in richness is one of the oldest and better supported. Alternatively, the mid-domain hypothesis is one of the most recent and controversial hypotheses; this hypothesis suggests that diversity gradients are simply a consequence of the random distribution of species that are subjected to geometric constraints imposed by a limited potential domain of distribution. In this study, we investigate the causes for species richness gradients of bats in the New World. We quantify the amount of variation in richness that can be attributed to mid-domain effects, and test whether environmental characteristics can explain richness gradients even after accounting for mid-domain effects imposed by geometric constraints. To do this, we constructed 1000 diversity gradients that could be expected under mid-domain effects, and we compared these random richness gradients with empirical data. These analyses were repeated for three groups of bats: Noctilionoidea, Molossidae and Vespertilionidae. Our results suggest that mid-domain effects can be important for diversity gradients in Noctilionoidea and Molossidae, but not Vespertilionidae. In contrast, the importance of environmental gradients is evident for all species groups. However, the relative importance of energy or heterogeneity depends on the way that environmental gradients are assumed to affect richness gradients: 1) if environmental variables directly affect the number of co-existing species in a particular region of the New World, then it is clear that energy is more important than heterogeneity; but, 2) if environmental variables affect richness gradients by modifying the pattern expected by mid-domain effects, then both energy and heterogeneity have similar magnitude of their effects.

Can stochastic models of geographical evolution recreate macroecological richness-environment correlations?

by J. Sebastian Tello

Tello, J. S. and Stevens, R. D. Accepted. Global Ecology and Biogeography.

Aim. Richness gradients are frequently correlated with environmental characteristics at broad geographic scales. In... more Aim. Richness gradients are frequently correlated with environmental characteristics at broad geographic scales. In particular, richness is often associated with energy and climate, while environmental heterogeneity is rarely the best correlate.These correlations have been interpreted as evidence in favour of environmental determinants of diversity gradients, particularly energy and climate. This interpre-
tation assumes that the expected-by-random correlation between richness and environment is zero, and that this is equally true for all environmental characteristics. However, these expectations might be unrealistic. We investigated to what degree basic evolutionary/biogeographical processes occurring independently of environment could lead to richness gradients that correlate with environmental characteristics by chance alone.

Location. Africa, Australia, Eurasia and the New World.

Methods. We produced artificial richness gradients based on a stochastic simulation model of geographic diversification of clades. In these simulations, species speciate, go extinct and expand or shift their distributions independently of any environmental characteristic. One thousand two hundred repetitions of this model were run, and the resulting stochastic richness gradients were regressed against real-world environmental variables. Stochastic species–environment relationships were then compared among continents and among three environmental characteristics: energy, environmental heterogeneity and climate seasonality.

Results. Simulations suggested that a significant degree of correlation between richness gradients and environment is expected even when clades diversify and species distribute stochastically. These correlations vary considerably in strength; but in the best cases, environment can spuriously account for almost 80% of variation in stochastic richness. Additionally, expected-by-chance relationships were different among continents and environmental characteristics, producing stronger relationships with energy and climate than with heterogeneity.

Main conclusions. We conclude that some features of empirical species-environment relationships can be reproduced just by chance when taking into account evolutionary/biogeographical processes underlying the construction of species richness gradients. Future tests of environmental effects on richness should consider structure in richness–environmental correlations that can be produced by simple evolutionary null models. Research should move away from the naive non-biological null hypotheses that are implicit in traditional statistical tests.

Body size, biomic specialization and range size of African large mammals

by Manuel Hernández Fernández