Metabolic Theory of Ecology and diversity of continental zooplankton in Brazil / A Teoria Metabólica da Ecologia e a diversidade do zooplâncton continental no Brasil

Several ecological hypotheses try to explain geographical patterns in biodiversity. The Metabolic Theory of Ecology (MTE) predicts that temperature is the main determinant of richness patterns for ectothermic organisms and that the relationship between richness (lnS) and temperature (1/kT) is a linear relationship with angular coefficient (b) near -0.65. This study tested the MTE for continental zooplankton diversity in 63 lakes in Brazil. Copepoda, Cladocera and Rotifera, as well as the three groups combined, showed different patterns from that predicted by MTE, with b values equal to 0.871, 0.516, 0.720 and 0.901, respectively. Temperature explains 12.7% of the richness of Copepoda, 5.3% of Cladocera, 6.7% of Rotifera, and 11.4% of all zooplankton groups together. Several studies have shown that the MTE does not apply to many terrestrial groups, perhaps because the model does not consider variances generated by other factors such as environmental spatial range, body size and other variables. The present study confirms this point of view, expanding it to continental aquatic invertebrates as well.

Várias hipóteses ecológicas tentam explicar os padrões geográficos de biodiversidade. A Teoria Metabólica da Ecologia (Metabolic Theory of Ecology - MTE) prediz que a temperatura é o principal determinante dos padrões de riqueza de organismos ectotérmicos e que a relação entre riqueza (lnS) e temperatura (1/kT) é uma reta com coeficiente angular (b) próximo a -0,65. O presente estudo testou a MTE para a diversidade zooplanctônica continental em 63 lagos brasileiros. Copepoda, Cladocera e Rotifera, assim como os três grupos analisados em conjunto, apresentaram padrões diferentes do previsto pela MTE, com os valores de b iguais a 0,871; 0,516; 0,720 e 0,901, respectivamente. A temperatura explicou 12,7% da riqueza de Copepoda, 5,3% de Cladocera, 6,7% de Rotifera e 11,4% do zooplâncton total. Diversos trabalhos têm demonstrado que a MTE não se aplica a muitos grupos terrestres, talvez porque o modelo não prevê desvios ocasionados por fatores como a variação espacial no ambiente, o tamanho corporal e outras variáveis. O presente trabalho corrobora este ponto de vista, expandindo-o também para invertebrados aquáticos continentais.

The three phases of the ensemble forecasting of niche models: geographic range and shifts in climatically suitable areas of Utetheisa ornatrix (Lepidoptera, Arctiidae) / As três fases da projeção combinada de modelos de nicho: distribuição geográfica e deslocamento de áreas climaticamente adequadas para Utetheisa ornatrix (Lepidoptera, Arctiidae)

Species' geographic ranges are usually considered as basic units in macroecology and biogeography, yet it is still difficult to measure them accurately for many reasons. About 20 years ago, researchers started using local data on species' occurrences to estimate broad scale ranges, thereby establishing the niche modeling approach. However, there are still many problems in model evaluation and application, and one of the solutions is to find a consensus solution among models derived from different mathematical and statistical models for niche modeling, climatic projections and variable combination, all of which are sources of uncertainty during niche modeling. In this paper, we discuss this approach of ensemble forecasting and propose that it can be divided into three phases with increasing levels of complexity. Phase I is the simple combination of maps to achieve a consensual and hopefully conservative solution. In Phase II, differences among the maps used are described by multivariate analyses, and Phase III consists of the quantitative evaluation of the relative magnitude of uncertainties from different sources and their mapping. To illustrate these developments, we analyzed the occurrence data of the tiger moth, Utetheisa ornatrix (Lepidoptera, Arctiidae), a Neotropical moth species, and modeled its geographic range in current and future climates.

A distribuição geográfica das espécies tem sido considerada como a unidade básica em macroecologia e biogeografia, mas ainda há dificuldades em mensurá-la de forma adequada, por diferentes razões. Há cerca de 20 anos atrás, os pesquisadores começaram a utilizar dados locais da ocorrência das espécies para estimar essas distribuições utilizando modelos de nicho ecológico. Entretanto, ainda há uma série de problemas na avaliação dos modelos e em suas aplicações, e uma das soluções é utilizar um consenso de diferentes modelos, projeções climáticas, cenários de emissão e combinação de variáveis, que são fontes de incerteza durante o processo de modelagem de nicho. Neste artigo nós discutimos essa abordagem de consenso e a dividimos em três fases, com níveis crescentes de complexidade. A Fase I é simplesmente a combinação de mapas e a obtenção e interpretação de um único mapa de consenso. A Fase II envolve a descrição das diferenças entre os mapas utilizando técnicas de análise multidimensional, enquanto que a Fase III consiste em analisar quantitativamente e mapear a magnitude relativa das diferentes fontes de incerteza. A fim de ilustrar essa abordagem, nós analisamos dados de ocorrência de Utetheisa ornatrix (Lepidoptera, Arctiidae), uma mariposa distribuída na região Neotropical, modelando sua distribuição geográfica com base em dados climáticos atuais e projeções de mudança climática.

A review of techniques for spatial modeling in geographical, conservation and landscape genetics

Most evolutionary processes occur in a spatial context and several spatial analysis techniques have been employed in an exploratory context. However, the existence of autocorrelation can also perturb significance tests when data is analyzed using standard correlation and regression techniques on modeling genetic data as a function of explanatory variables. In this case, more complex models incorporating the effects of autocorrelation must be used. Here we review those models and compared their relative performances in a simple simulation, in which spatial patterns in allele frequencies were generated by a balance between random variation within populations and spatially-structured gene flow. Notwithstanding the somewhat idiosyncratic behavior of the techniques evaluated, it is clear that spatial autocorrelation affects Type I errors and that standard linear regression does not provide minimum variance estimators. Due to its flexibility, we stress that principal coordinate of neighbor matrices (PCNM) and related eigenvector mapping techniques seem to be the best approaches to spatial regression. In general, we hope that our review of commonly used spatial regression techniques in biology and ecology may aid population geneticists towards providing better explanations for population structures dealing with more complex regression problems throughout geographic space.

Modeling body size evolution in Felidae under alternative phylogenetic hypotheses

The use of phylogenetic comparative methods in ecological research has advanced during the last twenty years, mainly due to accurate phylogenetic reconstructions based on molecular data and computational and statistical advances. We used phylogenetic correlograms and phylogenetic eigenvector regression (PVR) to model body size evolution in 35 worldwide Felidae (Mammalia, Carnivora) species using two alternative phylogenies and published body size data. The purpose was not to contrast the phylogenetic hypotheses but to evaluate how analyses of body size evolution patterns can be affected by the phylogeny used for comparative analyses (CA). Both phylogenies produced a strong phylogenetic pattern, with closely related species having similar body sizes and the similarity decreasing with increasing distances in time. The PVR explained 65% to 67% of body size variation and all Moran's I values for the PVR residuals were non-significant, indicating that both these models explained phylogenetic structures in trait variation. Even though our results did not suggest that any phylogeny can be used for CA with the same power, or that ôgoodõ phylogenies are unnecessary for the correct interpretation of the evolutionary dynamics of ecological, biogeographical, physiological or behavioral patterns, it does suggest that developments in CA can, and indeed should, proceed without waiting for perfect and fully resolved phylogenies.

Extinction of mammalian populations in conservation units of the Brazilian Cerrado by inbreeding depression in stochastic environments

Despite methodological and theoretical advances in conservation genetics, data on genetic variation on broad regional spatial scales are still scarce, leading conservation planners to use general heuristic or simulation models for an integrated analysis of genetic, demographic and landscape parameters. Here, we extended previous results by evaluating spatial patterns of extinction by inbreeding depression under stochastic variation of environments for mammalian populations in 31 conservation units of the Brazilian Cerrado. We observed a large spatial variation of times to extinction, for different conservation units and body-size classes of species. For small-bodied species (500 g), the population times to extinction in the conservation units were usually longer than 200 years, whereas for medium-bodied (5 kg) and large-bodied (50 kg) species this time was considerably shorter, and only a few units would maintain viable populations for more than 100 years. These figures are consistent with the current status of mammalian conservation in Brazil, and hopefully the simulated scenarios can be integrated to patterns of human occupation and habitat loss in the biome, in order to furnish overall guidelines for biodiversity conservation.

Population structure of Eupemphix nattereri (Amphibia, Anura, Leiuperidae) from Central Brazil

This study reports on 156 specimens of the amphibian Eupemphix nattereri, a widely distributed leiuperid, obtained from 11 municipalities of central Brazil. The extent of genetic variation was quantified by determining the mean number of alleles per locus and the proportion of polymorphic loci. An analysis of molecular variance (AMOVA) was performed on the random amplified polymorphic DNA (RAPD) haplotypes. The genetic distances obtained by calculating pairwise phist among local samples were used to determine population relationships using the unweighted pair-group method (UPGMA) and non-metric multidimensional scaling (NMDS). The cophenetic correlation was calculated to confirm agreement between the genetic matrix and the unweighted pair group method with averages (UPGMA) dendrogram. To determine if genetic distances were correlated to geographical distances we constructed pairwise genetic distance and geographical distance matrices and compared them using the Mantel test. The AMOVA results indicated significant genetic differences (p < 0.001) between E. nattereri populations, representing 69.5 percent of the within population genetic diversity. The Mantel test showed no significant correlation (r = 0.03; p = 0.45) between the genetic and geographical distance matrices. Our findings indicate that the genetic variation of E. nattereri populations was randomly distributed in geographic space and that gene flow for this species is probably structured at spatial scales smaller than those between our samples.

Extinction of canid populations by inbreeding depression under stochastic environments in Southwestern Goiás State: a simulation study

A frequently addressed question in conservation biology is what is the chance of survival for a population for a given number of years under certain conditions of habitat loss and human activities. This can be estimated through an integrated analysis of genetic, demographic and landscape processes, which allows the prediction of more realistic and precise models of population persistence. In this study, we modeled extinction in stochastic environments under inbreeding depression for two canid species, the maned wolf (Chrysocyon brachiurus) and the crab-eating fox (Cerdocyon thous), in southwest Goiás State. Genetic parameters were obtained from six microsattelite loci (Short Tandem Repeats - STR), which allowed estimates of inbreeding levels and of the effective population size under a stepwise mutation model based on heterozygosis. The simulations included twelve alternative scenarios with varying rates of habitat loss, magnitude of population fluctuation and initial inbreeding levels. ANOVA analyses of the simulation results showed that times to extinction were better explained by demographic parameters. Times to extinction ranged from 352 to 844, in the worst and best scenario, respectively, for the large-bodied maned wolf. For the small-bodied crab-eating fox, these same estimates were 422 and 974 years. Simulations results are within the expectation based on knowledge about species' life history, genetics and demography. They suggest that populations can persist through a reasonable time (i.e., more than 200 years) even under the worst demographic scenario. Our analyses are a starting point for a more focused evaluation of persistence in these populations. Our results can be used in future research aiming at obtaining better estimates of parameters that may, in turn, be used to achieve more appropriate and realist population viability models at a regional scale.

Prevalência de talassemias e hemoglobinas variantes no estado de Goiás, Brasil / Prevalence of thalassemias and variant hemoglobins in the state of Goiás, Brazil

As anemias hereditárias, em especial as talassemias e hemoglobinas (Hb) variantes, são as mais comuns das alterações genéticas humanas; sua frequência na população brasileira é muito variável, dependendo dos grupos raciais formadores de cada região. O povoamento de Goiás, que teve início logo após o seu descobrimento, em 1726, motivado pela procura de ouro, foi composto principalmente por portugueses e escravos africanos, contexto que favoreceu a mestiçagem entre eles. Considerando que esses povos apresentam genes para as hemoglobinas anormais com frequências variadas, é esperado que se encontrem essas alterações genéticas na nossa população. O objetivo deste trabalho foi avaliar a a prevalência de talassemias e hemoglobinas variantes na população de Goiás. Para isso a casuística foi composta por 404 alunos participantes dos diversos cursos da Universidade Católica de Goiás (UCG), oriundos de 55 cidades do estado de Goiás. A prevalência de anemia hereditária por talassemias e hemoglobinas variantes em Goiás foi de 10,1 por cento, cuja ordem decrescente foi a seguinte: talassemia alfa heterozigótica (5,2 por cento), heterozigose para hemoglobina S (Hb AS) (2,2 por cento), heterozigose para hemoglobina C (Hb AC) (1 por cento), talassemia beta menor (0,7 por cento), associa��o entre talassemia alfa e heterozigose para Hb S (0,5 por cento), associação entre talassemia alfa e heterozigose para Hb C (0,3 por cento) e heterozigose para hemoglobina D (Hb AD) (0,3 por cento). Nenhum caso de homozigose foi encontrado no presente estudo. Este trabalho demonstrou a dispersão dos genes para Hb S, Hb C e Hb D, bem como de talassemias alfa e beta em uma população do estado de Goiás. Por essa razão, concluímos que é importante realizar programas com maior abrangência da população para estudo da epidemiologia das talassemias e hemoglobinas variantes no estado de Goiás.

The hereditary anemias, especially the thalassemies and hemoglobinopathies are the most common human genetic abnormalities. Their frequency in the Brazilian population is very variable depending on the racial groups typical of each region. The settlement of Goiás, that had its beginning after discovery in 1726 owing to the search for gold, was composed basically by Portuguese and African slaves, a context that favored the racial mixing among them. Considering that these groups present genes for abnormal hemoglobins with varied frequencies it is expected the finding of these genetic abnormalities within our population. The objective of this study was to evaluate the prevalence of thalassemies and variant hemoglobins in the population of Goiás. For this purpose the sample was composed by 404 participating students from several graduate courses of the Catholic University of Goiás originally from 55 cities of the state of Goiás. Laboratory tests were used taking into account the historical and demographic factors of the population. The prevalence of hereditary anemias by thalassemias and variant hemoglobins in Goiás was 10.1 percent, in which the decreasing order of these abnormalities was: alfa heterozygous thalassemy (5.2 percent); heterozygous hemoglobin S (Hb AS) (2.2 percent); heterozygous hemoglobin C (Hb AC) (1 percent); beta short thalassemy (0.7 percent); association between alpha thalassemy and heterozygous for hemoglobin S (0.5 percent); association between alpha thalassemy and heterozygous for hemoglobin C (0.3 percent); and heterozygous for hemoglobin D (0.3 percent). No homozygosity was found in the study group. This study demonstrates the need for large scale screening in human populations for epidemiological studies of the thalassemies and variant hemoglobins in the state of Goiás.

Optimization procedures for establishing reserve networks for biodiversity conservation taking into account population genetic structure

Conservation genetics has been focused on the ecological and evolutionary persistence of targets (species or other intraspecific units), especially when dealing with narrow-ranged species, and no generalized solution regarding the problem of where to concentrate conservation efforts for multiple genetic targets has yet been achieved. Broadly distributed and abundant species allow the identification of evolutionary significant units, management units, phylogeographical units or other spatial patterns in genetic variability, including those generated by effects of habitat fragmentation caused by human activities. However, these genetic units are rarely considered as priority conservation targets in regional conservation planning procedures. In this paper, we discuss a theoretical framework in which target persistence and genetic representation of targets defined using multiple genetic criteria can be explicitly incorporated into the broad-scale reserve network models used to optimize biodiversity conservation based on multiple species data. When genetic variation can be considered discrete in geographical space, the solution is straightforward, and each spatial unit must be considered as a distinct target. But methods for dealing with continuous genetic variation in space are not trivial and optimization procedures must still be developed. We present a simple heuristic and sequential algorithm to deal with this problem by combining multiple networks of local populations of multiple species in which minimum separation distance between conserved populations is a function of spatial autocorrelation patterns of genetic variability within each species.

Seleção de áreas de interesse ecológico através de sensoriamento remoto e de otimização matemática: um estudo de caso no município de Cocalinho, MT / Selection of areas of ecological importance through remote sensing and mathematics optimization: a case study in the municipality of Cocalinho, Mato Grosso

A criação de unidades de conservação tem sido a principal estratégia para preservar a biodiversidade. O recente emprego de técnicas como o sensoriamento remoto e a otimização matemática, aliados a dados biológicos, ajudam a definir as áreas prioritárias para conservação, indicando a representação máxima da biodiversidade com base em medidas de complementaridade. O presente trabalho objetivou selecionar áreas de interesse ecológico, com base na heterogeneidade de hábitats, através da integração de imagens de satélite com dados biológicos, em Cocalinho, MT. As 66 parcelas quadradas estabelecidas foram comparadas com base na heterogeneidade e na representatividade mínima (ha) dos ambientes em cada parcela, através do programa SITES. O parque de cerrado é a fitofisionomia predominante em Cocalinho (38,44 por cento). A região central do município concentrou o maior agrupamento de parcelas, indicando a maior heterogeneidade de hábitats do local. Oficialmente, 6 por cento da área total do município estão protegidos em duas unidades de conservação na categoria de Refúgios de Vida Silvestre. Esses refúgios foram demarcados em locais com cobertura vegetal homogênea e sem considerar a composição faunística e florística. O modelo usado neste estudo pode ser uma boa abordagem a ser empregada no processo de indicação de novas unidades de conservação no bioma Cerrado ou em outros biomas do Brasil.

Phylogenetic autocorrelation and evolutionary diversity of Carnivora (Mammalia) in Conservation Units of the New World

One of the main concerns of Conservation Biology is the identification of priority areas for conservation, and the development of quantitative methods is important to achieve this task. Many phylogenetic diversity indexes and higher-taxon approaches have been used in this context. In this study, Faith's phylogenetic indexes and the number of evolutionary independent lineages of Carnivora were calculated at the average patch level based on phylogenetic autocorrelation analysis of phenotypic traits, in 18 conservation units in America (frequently National Parks). Despite controversies about the hierarchical level to be adopted, the characters included in this study suggest that the family level produces independent units for the analysis of phenotypic diversity in Carnivora. A positive correlation between species richness and the number of evolutionary independent lineages appeared (r = 0.67; P < 0.05), showing that this is a valid criterion to priorize conservation areas. Faith's phylogenetic diversity index is also highly correlated with species richness (r = 0.87; P < 0.05), as well as with the number of evolutionary independent lineages (r = 0.89; P < 0.05). Thus, the conservation units with more species have also more evolutionary information to be preserved.

Distribuição de abundância e tamanho do corpo de invertebrados do folhiço em uma floresta de terra firme na Amazônia Central, Brasil / Abundance and body size distribution of invertebrates of leaf litter in Amazonian forest, Brazil

Abundace and body size distribution of invertebrates of leaf litter in Amazonian forest, Brazil. Based on 605 invertebrates sampled of the litter in an Amazonian Forest, some basic macroecological patterns for this assemblage were described. The relationship between abundance and body size, at logarithmic scale, was triangular, and the distribution of species was constrained in an asymmetric triangular envelope, that was tested using null model procedures in ECOSIM (P= 0,0002). The most abundant species were at an intermediated body size. The relationship between maximum abundance with different mean body size classes confirmed the Energetic Equivalent Rule (b = -1,069; t-0,75 = -2,13; P = 0.079). This way, species tend to consume energy from the community independent of their body size, since requirements are compensated by local population density

Hypothesis testing of genetic similarity based on RAPD data using Mantel tests and model matrices

Clustering and ordination procedures in multivariate analyses have been widely used to describe patterns of genetic distances. However, in some cases, such as when dealing with Jaccard coefficients based on RAPD data, these techniques may fail to represent genetic distances because of the high dimensionality of the genetic distances caused by stochastic variation in DNA fragments among the units analyzed (species or populations). In this note, we show how Mantel tests can be used to test hypotheses about genetic distances and avoid problems with multivariate data representation. The procedure is illustrated with RAPD data comparing 20 anuran species from the cerrado, in which Jaccard genetic distances were compared to three model matrices linking the species at distinct taxonomic levels

Null expectation of spatial correlograms under a stochastic process of genetic divergence with small sample sizes

Nesse artigo, um processo estocástico Ornstein-Uhlenbeck foi utilizado para simular a relaçäo exponencial entre divergência genética e distância geográfica, conforme é esperado em modelos de isolamento-por-distância, alpondras ou coalescência. As simulaçöes foram realizadas a partir de um dendrograma UPGMA estimado a partir das distâncias geográficas entre 13 populaçöes locais. As superfícies espaciais de freqüências alélicas simuladas foram analisadas através de autocorrelaçäo espacial e construçäo de distâncias genéticas de Nei, com base em diferentes números de alelos. A divergência entre populaçöes locais produziu padröes espaciais significativos, tanto em nível univariado (correlogramas espaciais) quanto em nível multivariado (teste de Mantel entre distâncias de Nei e distâncias geográficas). Entretanto, se as análises säo baseadas em um pequeno número de populaçöes locais, os perfis dos correlogramas variam consideravelmente e as distâncias Manhattan calculadas entre eles podem ser maiores do que as previamente estabelecidas em outros estudos de simulaçäo. O método proposto permite assim estabelecer uma amplitude de perfis que podem ser obtidos pelo mesmo processo estocástico de divergência genética. A comparaçäo de correlogramas observados com esses perfis permite assim evitar o uso de outros mecanismos microevolutivos para explicar essa divergência genética.

Spatial pattern and genetic diversity estimates are linked in stochastic models of population differentiation

Nessa comunicaçäo, nós utilizamos análises de dados simulados e reais para demonstrar que, sob processos estocásticos de diferenciaçäo entre populaçöes, os conceitos de heterogeneidade espacial e padräo espacial säo equivalentes. Nesses processos, a proporçäo de variaçäo entre populaçöes locais, estimada com base nas estatísticas FST, GST ou èP, está correlacionada com o coeficiente angular do teste de Mantel relacionando distâncias genéticas de Nei e distâncias geográficas. O intercepto dessa regressäo matricial indica o valor da divergência genética quando a distância geográfica é zero, estando assim correlacionado com o valor de 1-GST. Além do interesse conceitual, a avaliaçäo da relaçäo entre medidas de heterogeneidade e padräo espacial pode ser utilizada para testar desvios de processos estocásticos de divergência genética, comparando diferentes loci ou grupos de espécies.

Phylogenetic correlograms and the evolution of body size in South American owls (Strigiformes)

Nos últimos anos diversos modelos têm sido propostos a fim de realizar inferências sobre processos microevolutivos com base em padröes macroevolutivos obtidos a partir de dados comparativos. Dentre esses, o movimento Browniano e o processo Ornstein-Uhlenbeck (O-U) têm sido utilizados para modelar principalmente deriva genética e seleçäo estabilizadora, respectivamente. Esses modelos produzem curvas diferentes de relaçäo entre variância interespecífica e distância no tempo, de modo que eles podem ser distingüidos com base em correlogramas filogenéticos. Neste trabalho, nós analisamos a variaçäo interespecífica no tamanho do corpo de 19 espécies de corujas (Strigiformes) sul-americanas através de correlogramas filogenéticos, construídos utilizando índices I de Moran em quatro classes de distância. A filogenia entre as espécies foi definida com base em dados de hibridizaçäo de DNA. O correlograma observado foi entäo comparado a 500 correlogramas obtidos através de simulaçöes de evoluçäo por movimento Browniano e pelo processo O-U, sobre essa mesma filogenia. Esses correlogramas foram comparados entre si utilizando análises de variância (ANOVA e MANOVA) e através das correlaçöes entre os índices I de Moran e as classes de distância filogenética. O correlograma observado indica a existência de um gradiente filogenético de variaçäo até cerca de 45 milhöes de anos, quando os índices se estabilizam, e é similar aos correlogramas obtidos através do processo O-U, considerando tanto a correlaçäo do gradiente quanto a sua alocaçäo aos dois grupos de processos através de análise discriminante. Esse padräo é esperado, considerando a importância do tamanho do corpo e sua correlaçäo com diversos caracteres ecológicos e de história de vida, que produzem muitas restriçöes que podem de fato ser modeladas por um processo O-U expressando seleçäo estabilizadora.

Spatial patterns and the macroecology of South American viperid snakes

The macroecological relationship between geographic range size and body size has been described recently as an envelope region defined in bivariate space and limited by ecological and physical constraints. These constraints can be explained by selective processes acting at different levels and theories for an optimal body size. However, since data are obtained for different species in a large taxonomic group, at continental scales, it is possible that these variables may be strongly affected by spatial and phylogenetic autocorrelations. In this paper, we analyzed data on geographic range size (GRS) and body size (BS) for 36 species of Viperid snakes from South America, searching for spatial trends that could affect the shape of the macroecological constraint space. Data were analyzed using spatial autocorrelation and trend surface analyses, detecting a significant spatial pattern for GRS, fitted by a quadratic trend (R2 = 0.665; P < 0.001). After removing this effect, the relationship between trend residuals for GRS and BS still forms a constraint space, in such a way that results for South American Viperid snakes support both the shape of constraint space previously observed in other taxonomic groups and the ecological and evolutionary processes developed to explain it.