Disentangling the phylogenetic and ecological components of spider phenotypic variation

An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure.An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic rel9519FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãoWe would like to thank M. Belisário, T.N. Bernabé, T.S. Coser, R. Marques, F. Moreira, D. Mota and E.S. Soeiro for their invaluable assistance in the field work. We thank N. Kraft, D.B. Provete, D.N. Reznick and anonymous reviewers for constructive comme

GRADIENTES DE DIVERSIDADE E A TEORIA METABÓLICA DA ECOLOGIA

There is an ongoing debate about the mechanisms involved in the origin and maintenance of geographical patterns in species richness. An attempt to explain these patterns is the Metabolic Theory of Ecology (MTE) was proposed. The MTE assumes that species richness patterns are related to environmental temperature, which influences on individual metabolism. In this paper, we show that although controversial in some aspects, the MTE differs from other theories by making precise predictions about species richness patterns in large spatial scale and proposing that an environmental variable (temperature) influences these patterns. These predictions make the theory testable and falsifiable, which has caused a considerable debate in Ecology in the last years. Thus, here we analyze the MTE impact on the scientific literature, via a scientometric analyses, as well as describing the basic principles of this theory and point out their main advantages and disadvantages. Although MTE has being highly cited by main ecology journals, it does not apply to most of ecological processes, because it does not consider fundamental features that, in general, drive the diversity patterns.Existe un debate continuo en la literatura ecológica sobre los mecanismos que determinan los patrones espaciales de la riqueza de especies. Una de las tentativas de encontrar explicaciones para estos patrones es la Teoría Metabólica de la Ecología, (MTE -- Metabolic Theory of Ecology). La MTE asume que los patrones de distribución de las especies están relacionados con la temperatura y que ésta interfiere en el metabolismo de los individuos. En este trabajo, mostraremos que a pesar de generar controversia en varios aspectos, la MTE difiere de las demás hipótesis desarrolladas para explicar los gradientes de riqueza por hacer predicciones precisas en relación a los patrones de riqueza de especies a gran escala y proponer que una variable ambiental principal (la temperatura) influye en esos patrones. Estas predicciones hacen que la teoría sea susceptible de ser verificada o rechazada, lo cual ha hecho que la MTE sea objeto de debates constantes en la ecología en los últimos años. De esta forma, en este artículo analizaremos la repercusión de la MTE en la literatura científica a través de análisis cienciométricos, describiremos los principios básicos de esta teoría y mostraremos sus principales ventajas y fallas al tratar de explicar los patrones latitudinales de riqueza de especies. A pesar de que la MTE es ampliamente citada en las principales revistas sobre ecología, no se aplica a la mayoría de procesos ecológicos, pues no considera factores fundamentales que generalmente rigen los patrones de diversidad.Há um contínuo debate na literatura ecológica sobre os mecanismos que determinam os padrões espaciais da riqueza de espécies. Uma das tentativas de encontrar explicações para esses padrões é a Teoria Metabólica da Ecologia (MTE -- Metabolic Theory of Ecology). A MTE assume que os padrões de distribuição de espécies estão relacionados à temperatura e que esta interfere no metabolismo dos indivíduos. Neste trabalho, mostraremos que, embora controversa em vários aspectos, a MTE difere das demais hipóteses desenvolvidas para explicar os gradientes de riqueza por fazer predições precisas em relação aos padrões de riqueza de espécies em ampla escala e propõe que uma variável ambiental influencia primariamente esses padrões (temperatura). Essas predições tornam a teoria testável e falseável, o que tem tornado a MTE alvo de constantes debates na ecologia nos últimos anos. Desta forma, neste artigo analisaremos a repercussão da MTE na literatura científica através de análises cienciométricas, descreveremos os princípios básicos dessa teoria e apontaremos suas principais vantagens e falhas ao tentar explicar os padrões latitudinais de riqueza de espécies. Apesar da MTE muito citada nos principais periódicos sobre ecologia, ela não se aplica à maioria dos processos ecológicos, pois não leva em consideração fatores fundamentais que, geralmente, regem os padrões de diversidade.

Potential suitable areas of giant ground sloths dropped before its extinction in South America:the evidences from bioclimatic envelope modeling

v. 10, n. 2, p. 145-151, 2012Here we analyze the effects that climatic changes through last ice age had on the potential distributions and extinction risk dynamics of two extinct species of South American giant ground sloths, Eremotherium laurillardi and Megatherium americanum. We tested the assumption of stability of the climate preferences through time for the two species and modeled their potential distributions at last glacial maximum (LGM, 21 ky BP) and mid-Holocene (6 ky BP) using Bioclimatic Envelope Modeling (BEM), fossil records and paleoclimatic simulations. The model predictions showed a drastic reduction of the geographical ranges for both species during mid-Holocene, along with a considerable fragmentation of their core climatic conditions and refugia, although it did not fully disappear at this time. Thus, our findings point out that the extinction risk of both species greatly increased as a consequence of the climate change, although do not support it as the unique stressor

Autocorrelação espacial, seleção de modelos e teste de hipóteses em ecologia geográfica: implicações para testar a teoria metabólica em anfíbios do Novo Mundo

In this paper, we stressed that avoiding significance tests under an alternative model selection framework does not mean that spatial autocorrelation no longer matters, since Akaike information criterion (AIC) is sensitive to the presence of spatial autocorrelation. We exemplify our discussion by analysing species richness patterns of American amphibians, in the context of metabolic theory, to understand how the presence of spatial autocorrelation in data affects data analysis under alternative frameworks of hypothesis testing and model selection. In general, temperature was found to be an important predictor of species richness in both frameworks, although particular predictions of metabolic theory were not fully satisfied when taking spatial autocorrelation into account. Key words: hypothesis testing; spatial autocorrelation; model selection; Akaike information criterion; macroecology; richness gradients; metabolic theory.Neste artigo, enfatiza-se que evitar os testes de significância baseados na seleção de modelos alternativos não significa que a autocorrelação espacial não ocorra, pois o critério de informação de Akaike (AIC) é sensível à presença de autocorrelação espacial. A discussão é exemplificada pela análise de padrões de riqueza de espécies de anfíbios americanos, no contexto da teoria metabólica, de forma a entender como a presença da autocorrelação afeta a análise dos dados com base em uma abordagem alternativa de teste de hipótese e seleção de modelos. Em geral, a temperatura foi uma importante preditora da riqueza de espécies em ambas as abordagens, embora predições específicas da teoria metabólica não foram completamente alcançadas quando consideramos a autocorrelação espacial. Palavras-chave: teste de hipóteses; autocorrelação espacial; seleção de modelos; critério de informação de Akaike; macroecologia; gradiente de riqueza; teoria metabólica

Ecological and evolutionary factors in the morphological diversification of South American spiny rats

Understanding the processes underlying morphological diversification is a central goal in ecology and evolutionary biology and requires the integration of information about phylogenetic divergence and ecological niche diversity. In the present study, we use geometric morphometrics and comparative methods to investigate morphological diversification in Neotropical spiny rats of the family Echimyidae. Morphological diversification is studied as shape variation in the skull, comprising a structure composed of four distinct units: vault, base, orognathofacial complex, and mandible. We demonstrate association among patterns of variation in shape in different cranial units, levels of phylogenetic divergence, and ecological niche diversification. At the lower level of phylogenetic divergence, there is significant and positive concordance between patterns of phylogenetic divergence and cranial shape variation in all cranial units. This concordance may be attributable to the phylogenetic and shape distances being calculated between species that occupy the same niche. At higher phylogenetic levels of divergence and with ecological niche diversity, there is significant concordance between shape variation in all four cranial units and the ecological niches. In particular, the orognathofacial complex revealed the most significant association between shape variation and ecological niche diversity. This association may be explained by the great functional importance of the orognathofacial complex.Facultad de Ciencias Naturales y Muse

Autocorrelação espacial, seleção de modelos e teste de hipóteses em ecologia geográfica: implicações para testar a teoria metabólica em anfíbios do Novo Mundo

In this paper, we stressed that avoiding significance tests under an alternative model selection framework does not mean that spatial autocorrelation no longer matters, since Akaike information criterion (AIC) is sensitive to the presence of spatial autocorrelation. We exemplify our discussion by analysing species richness patterns of American amphibians, in the context of metabolic theory, to understand how the presence of spatial autocorrelation in data affects data analysis under alternative frameworks of hypothesis testing and model selection. In general, temperature was found to be an important predictor of species richness in both frameworks, although particular predictions of metabolic theory were not fully satisfied when taking spatial autocorrelation into account. Key words: hypothesis testing; spatial autocorrelation; model selection; Akaike information criterion; macroecology; richness gradients; metabolic theory.Neste artigo, enfatiza-se que evitar os testes de significância baseados na seleção de modelos alternativos não significa que a autocorrelação espacial não ocorra, pois o critério de informação de Akaike (AIC) é sensível à presença de autocorrelação espacial. A discussão é exemplificada pela análise de padrões de riqueza de espécies de anfíbios americanos, no contexto da teoria metabólica, de forma a entender como a presença da autocorrelação afeta a análise dos dados com base em uma abordagem alternativa de teste de hipótese e seleção de modelos. Em geral, a temperatura foi uma importante preditora da riqueza de espécies em ambas as abordagens, embora predições específicas da teoria metabólica não foram completamente alcançadas quando consideramos a autocorrelação espacial. Palavras-chave: teste de hipóteses; autocorrelação espacial; seleção de modelos; critério de informação de Akaike; macroecologia; gradiente de riqueza; teoria metabólica

Ecological and evolutionary factors in the morphological diversification of South American spiny rats

Understanding the processes underlying morphological diversification is a central goal in ecology and evolutionary biology and requires the integration of information about phylogenetic divergence and ecological niche diversity. In the present study, we use geometric morphometrics and comparative methods to investigate morphological diversification in Neotropical spiny rats of the family Echimyidae. Morphological diversification is studied as shape variation in the skull, comprising a structure composed of four distinct units: vault, base, orognathofacial complex, and mandible. We demonstrate association among patterns of variation in shape in different cranial units, levels of phylogenetic divergence, and ecological niche diversification. At the lower level of phylogenetic divergence, there is significant and positive concordance between patterns of phylogenetic divergence and cranial shape variation in all cranial units. This concordance may be attributable to the phylogenetic and shape distances being calculated between species that occupy the same niche. At higher phylogenetic levels of divergence and with ecological niche diversity, there is significant concordance between shape variation in all four cranial units and the ecological niches. In particular, the orognathofacial complex revealed the most significant association between shape variation and ecological niche diversity. This association may be explained by the great functional importance of the orognathofacial complex.Facultad de Ciencias Naturales y Muse

Distribuição geográfica potencial da cobra coral Micrurus decoratus Jan, 1858 (Serpentes, Elapidae) na Floresta Atlântica do Brasil

The coralsnake Micrurus decoratus is restricted to the Atlantic Rain Forest from southeastern Brazil and data on its geographic distribution and natural history are poorly known. In this paper, we modeled its geographic range using the GARP program. Map was generated by combining the 20 best models and predicted the occurrence of Micrurus decoratus in the Atlantic Rain Forest, indicating the importance of this biome for the preservation of this species. Our study showed that ecological niche modeling might be an important computational tool to supplement traditional field studies in herpetology, allowing the identification of areas to be protected, and for the formulation of specific public policies for threatened species.A cobra coral Micrurus decoratus é uma espécie restrita à Mata Atlântica do Sudeste do Brasil e dados quanto a sua distribuição geográfica e história natural são pouco conhecidos. Neste trabalho, a distribuição geográfica dessa espécie foi modelada utilizando-se o programa de modelagem GARP. Foi gerado um mapa de predição de ocorrência de M. decoratus na Mata Atlântica por meio da combinação dos 20 melhores modelos resultantes da modelagem, indicando a importância desse bioma para a preservação da espécie. Este estudo mostrou que a modelagem do nicho ecológico pode representar importante ferramenta computacional para suplementar estudos de campo em herpetologia, permitindo a identificação de áreas prioritárias para conservação e formulação de políticas públicas específicas para espécies ameaçadas