Supplemental material, sj-pdf-1-trc-10.1177_19400829211017366 for Species-Area Relationships Indu... more Supplemental material, sj-pdf-1-trc-10.1177_19400829211017366 for Species-Area Relationships Induced by Forest Habitat Fragmentation Apply Even to Rarely Detected Organisms by Ana Filipa Palmeirim, Rafael de Fraga, Marcus V. Vieira and Carlos A. Peres in Tropical Conservation Science
Natural environments disturbed by human activities can suffer from species extinctions, but some ... more Natural environments disturbed by human activities can suffer from species extinctions, but some can still harbor high taxonomic diversity. However, disturbances may have impacts beyond the species level, if the species lost represent unique functions in the ecosystem. In this study, we evaluated to what extent the amount of habitat can determine the functional diversity and nestedness of amphibian communities in an Atlantic Forest fragmented landscape in Brazil, and if there is a threshold of habitat amount beyond which there is severe loss of functional diversity. As species responses may depend on their habitat type, we performed the analyses for three different sets of species: all species, forest‐dependent species, and generalist species. We also evaluated the relative importance of turnover and nestedness components to total functional dissimilarity among sites. Habitat amount affected functional diversity of frogs, especially for forest‐dependent species where a linear reduction was detected. The functional dissimilarity among sites was mostly explained by the nestedness component. The reduction of functional diversity was mediated by an ordered loss of traits, leading to a functionally nested metacommunity. These sensitive traits were closely related to habits and reproductive modes that depend on rivers and streams. The maintenance of functional diversity of frogs in fragmented landscapes must rely on the conservation of both terrestrial and aquatic environments, as some species and their traits can disappear from remnants of native vegetation lacking some specific habitats (e.g. streams)
Space and diet are frequently considered the two most important dimensions of an organism niche, ... more Space and diet are frequently considered the two most important dimensions of an organism niche, but in tropical forests, these two dimensions are associated, with fruits more accessible in the canopy and upper strata of the forest, and arthropods more abundant in the forest litter. This constitutes a genuine macroecological pattern, potentially common to all tropical forests. We tested the existence of this trade-off between frugivory-insectivory in the vertical strata, and if it results from feeding specializations, using didelphid marsupials as a model group. We compared nine species, representing different lineages, which differ in diet and use of the forest strata, using phylogenetically independent contrasts. We classified species according to their use of the vertical strata into four categories based on the literature (terrestrialsemiaquatic, terrestrial-understory, underestory-subcanopy-canopy, and canopy only). Diet was analyzed by the proportion of nutrients (carbohydrates, fibers, proteins and lipids) in a cafeteria food preference experiment: more frugivorous diets have higher carbohydrate and fiber content, whereas more carnivorous and insectivorous diets have higher protein and lipid content. Along the phylogeny, increases in use of the vertical strata were significantly associated with increases in carbohydrate and fiber contents, and reductions in lipid content. Levels of protein content also reduced with increasing use of the vertical strata, but this association was not significant. The macroecological pattern of increasing frugivory with use of the upper strata is supported by the results for didelphid marsupials, which also indicate specialization is a mechanism involved. The contribution of didelphid marsupials to the ecosystem process of frugivory and seed dispersal is performed by a subset of species, despite being broadly described as omnivorous. Future studies should evaluate this macroecological pattern in more specialized taxonomic groups that vary in the use of the vertical strata, and if specialization is the general mechanism involved.
MATHEMATICAL MODELS IN ECOLOGICAL THEORY: A REVIEW BY BRAZILIAN RESEARCHERS ON ITS CURRENT STATUS... more MATHEMATICAL MODELS IN ECOLOGICAL THEORY: A REVIEW BY BRAZILIAN RESEARCHERS ON ITS CURRENT STATUS AND PERSPECTIVES
We address two fundamental ecological questions: what are the limits to animal population density... more We address two fundamental ecological questions: what are the limits to animal population density and what determines those limits? We develop simple alternative models to predict population limits in relation to body mass. A model assuming that within-species area use increases with the square of daily travel distance broadly predicts the scaling of empirical extremes of minimum density across birds and mammals. Consistent with model predictions, the estimated density range for a given mass, 'population scope', is greater for birds than for mammals. However, unlike mammals and carnivorous birds, expected broad relationships between body mass and density extremes are not supported by data on herbivorous and omnivorous birds. Our results suggest that simple constraints on mobility and energy use/supply are major determinants of the scaling of density limits, but further understanding of interactions between dietary constraints and density limits are needed to predict future wildlife population responses to anthropogenic threats.
Accepted Article This article is protected by copyright. All rights reserved Biological invasion ... more Accepted Article This article is protected by copyright. All rights reserved Biological invasion is one of the main threats to native biodiversity. For a species to become invasive it must be voluntarily or involuntarily introduced by humans into a non-native habitat. Mammals were among first taxa to be introduced worldwide for game, meat and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in southeast USA) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g. Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly due to uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species C. aurita, C. flaviceps, C. geoffroyi, C. jacchus, C. kuhlii, C. penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when use the data in publications. We also request that researchers and teachers inform us on how they are using the data.
Natural environments disturbed by human activities can suffer from species extinctions, but some ... more Natural environments disturbed by human activities can suffer from species extinctions, but some can still harbor high taxonomic diversity. However, disturbances may have impacts beyond the species level, if the species lost represent unique functions in the ecosystem. In this study, we evaluated to what extent the amount of habitat can determine the functional diversity and nestedness of amphibian communities in an Atlantic Forest fragmented landscape in Brazil, and if there is a threshold of habitat amount beyond which there is severe loss of functional diversity. As species responses may depend on their habitat type, we performed the analyses for three different sets of species: all species, forest-dependent species, and generalist species. We also evaluated the relative importance of turnover and nestedness components to total functional dissimilarity among sites. Habitat amount affected functional diversity of frogs, especially for forest-dependent species where a linear reduction was detected. The functional dissimilarity among sites was mostly explained by the nestedness component. The reduction of functional diversity was mediated by an ordered loss of traits, leading to a functionally nested metacommunity. These sensitive traits were closely related to habits and reproductive modes that depend on rivers and streams. The maintenance of functional diversity of frogs in fragmented landscapes must rely on the conservation of both terrestrial and aquatic environments, as some species and their traits can disappear from remnants of native vegetation lacking some specific habitats (e.g. streams).
Food availability is considered to be a primary factor affecting animal populations, yet few expe... more Food availability is considered to be a primary factor affecting animal populations, yet few experimental tests have been performed to evaluate its actual importance in species-rich ecosystems such as rainforests. It has been suggested that in such systems certain plant species may act as "keystone" resources for animals, but the importance of presumed keystone resources for populations has not been quantified experimentally. Using complementary seed removal and seed-addition experiments, we determined how the supply of a presumed keystone resource, seeds of Araucaria angustifolia, affects short-term demography of their main consumer group (small rodents) in a biodiversity hotspot, the Brazilian Atlantic Forest. We hypothesized that (i) the harvest of A. angustifolia seeds by human populations has negative impacts on rodents, and (ii) these seeds are a limiting resource for rodent populations. To test these hypotheses, we monitored populations of two species of numerically dominant rodents (Delomys dorsalis and Akodon montensis) within replicated control-experimental plots. Manipulations of seed supply over 2 years had little effect on population size, body condition, survival, or reproduction of the two rodents, suggesting that, in the short-term (within one generation), their populations are not food limited in Araucaria forests. Despite apparently having all the characteristics of a keystone resource, as currently defined in the literature, the seeds of A. angustifolia had limited influence on the short-term demography of their main consumer group. In situations where purported keystone resources are seasonally abundant, their actual importance may be lower than generally assumed, and these resources then may have only localized and temporary effects on consumer populations.
Neotropical snakes have extremely low detection rates, hampering our understanding of their respo... more Neotropical snakes have extremely low detection rates, hampering our understanding of their responses to habitat loss and fragmentation. We addressed this gap using a limited sample (50 individuals, 16 species) across 25 variable-size insular forest fragments within a hydroelectric lake and four adjacent mainland continuous forest sites, in Central Brazilian Amazonia. The number of species recorded on forest islands (1.55 [Formula: see text] 0.78) was much lower than that at continuous forest sites (5.0 [Formula: see text] 3.1), with no snakes being recorded at twelve islands smaller than 30 ha. As such, snake assemblages were positively affected by forest area, explaining 48% of the number of species, and negatively affected by island isolation. The markedly higher number of species recorded across continuous forest sites likely results from the availability of riparian habitats, which have virtually disappeared from the archipelagic landscape given the widespread inundation of low...
A lista mais recente dos mamíferos que ocorrem no Parque Nacional da Serra dos Órgãos (PARNASO), ... more A lista mais recente dos mamíferos que ocorrem no Parque Nacional da Serra dos Órgãos (PARNASO), com 79 registros, consta no seu segundo Plano de Manejo, publicado em 2008. O presente estudo teve como objetivo atualizar a lista de espécies de mamíferos do PARNASO, inserindo novos registros de espécies obtidos através de dados primários e revisão bibliográfica, considerando o período de 2002 a 2018. A revisão da lista do Plano de Manejo resultou em 75 registros válidos. Destes, três espécies foram consideradas localmente extintas (Panthera onca, Tayassu pecari e Tapirus terrestris) e não foram incluídas na presente lista. Desse modo, listamos aqui 100 espécies com registros recentes no PARNASO, o que representa um acréscimo de 28 espécies. As ordens com maior riqueza de espécies foram Rodentia e Chiroptera, com 32 e 23 espécies, respectivamente. Das espécies registradas, quatro são invasoras (Callithrix jacchus, C. penicillata, Rattus norvegicus e R. rattus), três são domésticas (Bos taurus, Canis familiaris e Felis catus), e 26 são ameaçadas de extinção. A análise da distribuição espacial da riqueza de espécies mostrou que apenas metade da área do parque possui ao menos um registro, e que os registros estão concentrados onde há infraestrutura para a pesquisa. A presença de espécies domésticas e invasoras, bem como as extinções locais detectadas, indicam a necessidade de ações de manejo no interior do parque. Esse grande acréscimo de espécies à lista evidencia o desenvolvimento da pesquisa com mamíferos nesta Unidade de Conservação e a necessidade de compilações mais frequentes dos resultados devido aos vários projetos em curso. O PARNASO tem papel de destaque na conservação de mamíferos ao ainda manter uma das maiores riquezas de espécies do Estado do Rio de Janeiro, e grande importância para a pesquisa, abrigando uma ampla gama de estudos e projetos de longa duração.
We report the first record of homing behavior of a Neotropical marsupial, the opossum Philander f... more We report the first record of homing behavior of a Neotropical marsupial, the opossum Philander frenatus. The individual studied returned to the home forest fragment where it was captured (1050 m away) crossing a hostile matrix, instead moving to a much closer fragment (50 m distant). Movements did not follow wind or the direction of the closest fragment, but they were significantly oriented towards the home fragment. The individual probably had previous experience with the release site. This unique observation suggests that the ability of P. frenatus to overcome the effects of habitat fragmentation may be higher than considered previously. RESUMO: Comportamento de “homing” de Philander frenatus (Didelphimorphia, Didelphidae) em uma paisagem fragmentada da Mata Atlântica do Brasil. Relatamos o primeiro registro de comportamento de “homing” de um marsupial neotropical, Philander frenatus. O indivíduo estudado retornou para o fragmento onde foi capturado (distante 1050 m) atravessando...
We compare temporal variations in leaf fall among three sites of evergreen Atlantic Forest and an... more We compare temporal variations in leaf fall among three sites of evergreen Atlantic Forest and analyze how climatic variables influence it. Sites were located at Serra dos Órgãos National Park at different altitudes. Litter was collected monthly, from September 1997 to September 2005. Leaves were separated from other litter elements, oven-dried and weighted. Differences in leaf fall mass among grids and how they correlated with temporal variations were analyzed. Climatic variables were obtained from a nearby station and deviations from climatological normals were analyzed. We grouped climatic variables using Principal Component Analyses (PCA) and the highest scores of the two main factors were selected to construct regression models for different time lags. Leaf fall represented 50.5-70 percent of the total litter fall and mean leaf fall differed significantly among grids. However, leaf fall seasonality in the three areas were correlated. Leaf fall increased at the end of dry periods, when temperature and precipitation started to increase. Climatic variables were classified into two groups: seasonal and anomaly. Models constructed with lag variation from 0 and 6 months show that leaf fall was best explained by an anomaly in the maximum mean temperature, with lag 0, and by precipitation, with a six-month lag. We conclude that plant species respond immediately to drastic deviations from climatic factors, while regular climatic conditions are responsible for the seasonality of leaf fall, most likely as a late response to water shortage at the end of the dry season.
Climatic seasonality affects marsupial space use through changes in food, mate, and nest availabi... more Climatic seasonality affects marsupial space use through changes in food, mate, and nest availability. These effects can be enhanced when population size has an additive effect in the dry season. We tested if daily home range area and intensity of habitat use of the marsupial Metachirus nudicaudatus is affected by population size, climatic (dry and wet), and reproductive (breeding and non-breeding) seasons, and if it differs between genders. Metachirus nudicaudatus space use was affected by climatic seasonality, with individuals exploring larger areas in the dry season, probably in search for food. No effect of population size or differences in space use between sexes was detected. Further studies should test experimentally the effect of food availability on marsupials space use to confirm or rebut this hypothesis.
Recent studies suggest that habitat amount is the main determinant of species richness, whereas h... more Recent studies suggest that habitat amount is the main determinant of species richness, whereas habitat fragmentation has weak and mostly positive effects. Here, we challenge these ideas using a multi-taxa database including 2230 estimates of forest-dependent species richness from 1097 sampling sites across the Brazilian Atlantic Forest biodiversity hotspot. We used a structural equation modeling approach, accounting not only for direct effects of habitat loss, but also for its indirect effects (via habitat fragmentation), on the richness of forestdependent species. We reveal that in addition to the effects of habitat loss, habitat fragmentation has negative impacts on animal species richness at intermediate (30-60%) levels of habitat amount, and on richness of plants at high (> 60%) levels of habitat amount, both of which are mediated by edge effects. Based on these results, we argue that dismissing habitat fragmentation as a powerful force driving species extinction in tropical forest landscapes is premature and unsafe.
As florestas semidecíduas do interior do Estado de São Paulo são isoladas e pequenas devido às at... more As florestas semidecíduas do interior do Estado de São Paulo são isoladas e pequenas devido às atividades agrícolas, expansão urbana e industrial. Os remanescentes dos fragmentos florestais são importantes para a persistência de diversas espécies de mamíferos. Neste estudo foi feito um inventário da mastofauna de um fragmento de mata mesófila semidecídua no interior do Estado (Fazenda São José) nos municípios de Rio Claro e Araras. Nos três períodos amostrados, entre maio de 1997 e março de 1999, o levantamento da mastofauna foi feito por meio de armadilhas para pequenos mamíferos, bem como de observação direta e identificação de rastros dos animais. Registrou-se a ocorrência de três espécies de marsupiais (Didelphidae), duas de tatus (Dasipodidae), três de primatas (Callithrichidae e Cebidae), cinco de carnívoros (Canidae, Procyonidae e Mustelidae), uma de veado (Cervidae), sete de roedores (Sciuridae e Muridae) e uma de coelho (Leporidae). Didelphis albiventris (Didelphidae), Nect...
Oryzomyine rodents of Nectomys have a repertoire of swimming postural behaviors used in different... more Oryzomyine rodents of Nectomys have a repertoire of swimming postural behaviors used in different ecological aspects of its life, affecting key tasks of their survival. These species present three swimming behaviors: bipedal surface swimming, quadruped symmetric submerged swimming, and swimming bound, with correspondent differences in performance. Here we describe and measure the postural behavior in the swimming bound of Nectomys squamipes and N. rattus. Rodents were filmed at 30 frames s-1 in lateral view, swimming in a glass aquarium. Video sequences were analyzed dividing the swimming cycle into power and recovery phases. The two species did not differ in swimming behavior. Both species presented displacement of the head at vertical axis during impulsion, reaching its maximum displacement at the end of the phase. The power phase of the hindlimbs was primarily responsible for the animal propulsion. The flexion and extension of the head relative to the neck occurred in the impulsion and the recovery phase, respectively. During the hindlimbs power phase occurred the extension of the spine, raising the body of the animal above the water surface. The swimming bound allows a burst of speed and likely escape predation, hence involving specific postural behavior described here for the first time. These specific behaviors are related to morphological adaptations of spine, hindlimbs and feet, that allow spine extension and hindlimb thrust in an aquatic environment beyond the abilities of terrestrial rodents.
Medidas de desempenho utilizadas podem fornecer uma medida do nicho fundamental, permitindo preve... more Medidas de desempenho utilizadas podem fornecer uma medida do nicho fundamental, permitindo prever uso do habitat ou recursos na ausência de interações entre espécies. Propomos um conjunto padrão de testes de desempenho locomotor para vertebrados arborícolas, e um método para desenvolver modelos ecomorfológicos baseados em testes de desempenho e análise de caminhos. Os testes propostos simulam características do habitat como diâmetro e orientação de suportes. Modelos de relações entre variáveis podem ser formulados e comparados através da análise de caminhos, permitindo escolher o modelo de melhor ajuste aos dados. Este procedimento foi aplicado ao marsupial Philander frenata, comparando-se o efeito da forma corporal sobre o comprimento e freqüência de passadas no andar arborícola. O modelo incluindo caminhos tanto para freqüência como para comprimento de passadas teve um ajuste significativamente melhor que o modelo com caminhos apenas para o comprimento das passadas. Um modelo ger...
Differences in body size and in the use of arboreal strata limit the climbing behaviour and perfo... more Differences in body size and in the use of arboreal strata limit the climbing behaviour and performance of didelphids. Similarly to primates, the arboreal canopy dweller, Caluromys philander exhibits a diagonal-sequence gait. In contrast, terrestrial didelphids use a symmetrical lateral sequence in horizontal locomotion. Postural behaviour along thin supports may allow understanding the mechanisms behind the higher performance of arboreal didelphids climbing. Here in, we describe and compare gait sequence and postural behaviour of seven didelphids climbing a slender and flexible vertical support. Animals were stimulated to climb a vertical support of 1.25 cm diameter. Postural behaviour was qualitatively described for each species in the cycle of maximum velocity by a frame-by-frame analysis of gait cycles, evaluating (1) movements of the tail, (2) posture of hand and wrist when grasping, (3) distance of the body to the support, (4) lateral swinging of the body, (5) orientation of the head, (6) limb posture, and (7) stride cycle. Only arboreal species were capable of climbing with only two limbs grasping the support, keeping a straight body orientation at some distance from the support, and sustaining a more constant and regular climbing velocity. The tail played a role in didelphids with better climbing performance (i.e., higher relative velocity), counteracting the lateral swinging of the body, helping with the animal balance. However, the prehensile ability of the tail was not used in climbing. The most stunning result is that all didelphids grasped the rope between digits 2-3, a schizaxonic grasp, involving a neutral hand orientation regarding the ulna. The didelphids protracted the humerus at forelimb touchdown, and the angle between the arm and the horizontal body axis was greater than 90°. The same postures were already observed in horizontal locomotion of C. philander, Monodelphis domestica, and primates. Locomotory and postural adaptations for an arboreal lifestyle in didelphids seem to be limited to small to medium body sizes, up to the size of species of Caluromys. The arboreal locomotion of didelphids is an important key to understand adaptation and evolution of mammals to an arboreal niche, and the comparison with small primates may help to identify adaptive convergence to arboreal locomotion.
We study the population size time series of a Neotropical small mammal with the intent of detecti... more We study the population size time series of a Neotropical small mammal with the intent of detecting and modelling population regulation processes generated by density-dependent factors and their possible delayed effects. The application of analysis tools based on principles of statistical generality are nowadays a common practice for describing these phenomena, but, in general, they are more capable of generating clear diagnosis rather than granting valuable modelling. For this reason, in our approach, we detect the principal temporal structures on the bases of different correlation measures, and from these results we build an ad-hoc minimalist autoregressive model that incorporates the main drivers of the dynamics. Surprisingly our model is capable of reproducing very well the time patterns of the empirical series and, for the first time, clearly outlines the importance of the time of attaining sexual maturity as a central temporal scale for the dynamics of this species. In fact, an important advantage of this analysis scheme is that all the model parameters are directly biologically interpretable and potentially measurable, allowing a consistency check between model outputs and independent measurements.
Supplemental material, sj-pdf-1-trc-10.1177_19400829211017366 for Species-Area Relationships Indu... more Supplemental material, sj-pdf-1-trc-10.1177_19400829211017366 for Species-Area Relationships Induced by Forest Habitat Fragmentation Apply Even to Rarely Detected Organisms by Ana Filipa Palmeirim, Rafael de Fraga, Marcus V. Vieira and Carlos A. Peres in Tropical Conservation Science
Natural environments disturbed by human activities can suffer from species extinctions, but some ... more Natural environments disturbed by human activities can suffer from species extinctions, but some can still harbor high taxonomic diversity. However, disturbances may have impacts beyond the species level, if the species lost represent unique functions in the ecosystem. In this study, we evaluated to what extent the amount of habitat can determine the functional diversity and nestedness of amphibian communities in an Atlantic Forest fragmented landscape in Brazil, and if there is a threshold of habitat amount beyond which there is severe loss of functional diversity. As species responses may depend on their habitat type, we performed the analyses for three different sets of species: all species, forest‐dependent species, and generalist species. We also evaluated the relative importance of turnover and nestedness components to total functional dissimilarity among sites. Habitat amount affected functional diversity of frogs, especially for forest‐dependent species where a linear reduction was detected. The functional dissimilarity among sites was mostly explained by the nestedness component. The reduction of functional diversity was mediated by an ordered loss of traits, leading to a functionally nested metacommunity. These sensitive traits were closely related to habits and reproductive modes that depend on rivers and streams. The maintenance of functional diversity of frogs in fragmented landscapes must rely on the conservation of both terrestrial and aquatic environments, as some species and their traits can disappear from remnants of native vegetation lacking some specific habitats (e.g. streams)
Space and diet are frequently considered the two most important dimensions of an organism niche, ... more Space and diet are frequently considered the two most important dimensions of an organism niche, but in tropical forests, these two dimensions are associated, with fruits more accessible in the canopy and upper strata of the forest, and arthropods more abundant in the forest litter. This constitutes a genuine macroecological pattern, potentially common to all tropical forests. We tested the existence of this trade-off between frugivory-insectivory in the vertical strata, and if it results from feeding specializations, using didelphid marsupials as a model group. We compared nine species, representing different lineages, which differ in diet and use of the forest strata, using phylogenetically independent contrasts. We classified species according to their use of the vertical strata into four categories based on the literature (terrestrialsemiaquatic, terrestrial-understory, underestory-subcanopy-canopy, and canopy only). Diet was analyzed by the proportion of nutrients (carbohydrates, fibers, proteins and lipids) in a cafeteria food preference experiment: more frugivorous diets have higher carbohydrate and fiber content, whereas more carnivorous and insectivorous diets have higher protein and lipid content. Along the phylogeny, increases in use of the vertical strata were significantly associated with increases in carbohydrate and fiber contents, and reductions in lipid content. Levels of protein content also reduced with increasing use of the vertical strata, but this association was not significant. The macroecological pattern of increasing frugivory with use of the upper strata is supported by the results for didelphid marsupials, which also indicate specialization is a mechanism involved. The contribution of didelphid marsupials to the ecosystem process of frugivory and seed dispersal is performed by a subset of species, despite being broadly described as omnivorous. Future studies should evaluate this macroecological pattern in more specialized taxonomic groups that vary in the use of the vertical strata, and if specialization is the general mechanism involved.
MATHEMATICAL MODELS IN ECOLOGICAL THEORY: A REVIEW BY BRAZILIAN RESEARCHERS ON ITS CURRENT STATUS... more MATHEMATICAL MODELS IN ECOLOGICAL THEORY: A REVIEW BY BRAZILIAN RESEARCHERS ON ITS CURRENT STATUS AND PERSPECTIVES
We address two fundamental ecological questions: what are the limits to animal population density... more We address two fundamental ecological questions: what are the limits to animal population density and what determines those limits? We develop simple alternative models to predict population limits in relation to body mass. A model assuming that within-species area use increases with the square of daily travel distance broadly predicts the scaling of empirical extremes of minimum density across birds and mammals. Consistent with model predictions, the estimated density range for a given mass, 'population scope', is greater for birds than for mammals. However, unlike mammals and carnivorous birds, expected broad relationships between body mass and density extremes are not supported by data on herbivorous and omnivorous birds. Our results suggest that simple constraints on mobility and energy use/supply are major determinants of the scaling of density limits, but further understanding of interactions between dietary constraints and density limits are needed to predict future wildlife population responses to anthropogenic threats.
Accepted Article This article is protected by copyright. All rights reserved Biological invasion ... more Accepted Article This article is protected by copyright. All rights reserved Biological invasion is one of the main threats to native biodiversity. For a species to become invasive it must be voluntarily or involuntarily introduced by humans into a non-native habitat. Mammals were among first taxa to be introduced worldwide for game, meat and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in southeast USA) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g. Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly due to uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species C. aurita, C. flaviceps, C. geoffroyi, C. jacchus, C. kuhlii, C. penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when use the data in publications. We also request that researchers and teachers inform us on how they are using the data.
Natural environments disturbed by human activities can suffer from species extinctions, but some ... more Natural environments disturbed by human activities can suffer from species extinctions, but some can still harbor high taxonomic diversity. However, disturbances may have impacts beyond the species level, if the species lost represent unique functions in the ecosystem. In this study, we evaluated to what extent the amount of habitat can determine the functional diversity and nestedness of amphibian communities in an Atlantic Forest fragmented landscape in Brazil, and if there is a threshold of habitat amount beyond which there is severe loss of functional diversity. As species responses may depend on their habitat type, we performed the analyses for three different sets of species: all species, forest-dependent species, and generalist species. We also evaluated the relative importance of turnover and nestedness components to total functional dissimilarity among sites. Habitat amount affected functional diversity of frogs, especially for forest-dependent species where a linear reduction was detected. The functional dissimilarity among sites was mostly explained by the nestedness component. The reduction of functional diversity was mediated by an ordered loss of traits, leading to a functionally nested metacommunity. These sensitive traits were closely related to habits and reproductive modes that depend on rivers and streams. The maintenance of functional diversity of frogs in fragmented landscapes must rely on the conservation of both terrestrial and aquatic environments, as some species and their traits can disappear from remnants of native vegetation lacking some specific habitats (e.g. streams).
Food availability is considered to be a primary factor affecting animal populations, yet few expe... more Food availability is considered to be a primary factor affecting animal populations, yet few experimental tests have been performed to evaluate its actual importance in species-rich ecosystems such as rainforests. It has been suggested that in such systems certain plant species may act as "keystone" resources for animals, but the importance of presumed keystone resources for populations has not been quantified experimentally. Using complementary seed removal and seed-addition experiments, we determined how the supply of a presumed keystone resource, seeds of Araucaria angustifolia, affects short-term demography of their main consumer group (small rodents) in a biodiversity hotspot, the Brazilian Atlantic Forest. We hypothesized that (i) the harvest of A. angustifolia seeds by human populations has negative impacts on rodents, and (ii) these seeds are a limiting resource for rodent populations. To test these hypotheses, we monitored populations of two species of numerically dominant rodents (Delomys dorsalis and Akodon montensis) within replicated control-experimental plots. Manipulations of seed supply over 2 years had little effect on population size, body condition, survival, or reproduction of the two rodents, suggesting that, in the short-term (within one generation), their populations are not food limited in Araucaria forests. Despite apparently having all the characteristics of a keystone resource, as currently defined in the literature, the seeds of A. angustifolia had limited influence on the short-term demography of their main consumer group. In situations where purported keystone resources are seasonally abundant, their actual importance may be lower than generally assumed, and these resources then may have only localized and temporary effects on consumer populations.
Neotropical snakes have extremely low detection rates, hampering our understanding of their respo... more Neotropical snakes have extremely low detection rates, hampering our understanding of their responses to habitat loss and fragmentation. We addressed this gap using a limited sample (50 individuals, 16 species) across 25 variable-size insular forest fragments within a hydroelectric lake and four adjacent mainland continuous forest sites, in Central Brazilian Amazonia. The number of species recorded on forest islands (1.55 [Formula: see text] 0.78) was much lower than that at continuous forest sites (5.0 [Formula: see text] 3.1), with no snakes being recorded at twelve islands smaller than 30 ha. As such, snake assemblages were positively affected by forest area, explaining 48% of the number of species, and negatively affected by island isolation. The markedly higher number of species recorded across continuous forest sites likely results from the availability of riparian habitats, which have virtually disappeared from the archipelagic landscape given the widespread inundation of low...
A lista mais recente dos mamíferos que ocorrem no Parque Nacional da Serra dos Órgãos (PARNASO), ... more A lista mais recente dos mamíferos que ocorrem no Parque Nacional da Serra dos Órgãos (PARNASO), com 79 registros, consta no seu segundo Plano de Manejo, publicado em 2008. O presente estudo teve como objetivo atualizar a lista de espécies de mamíferos do PARNASO, inserindo novos registros de espécies obtidos através de dados primários e revisão bibliográfica, considerando o período de 2002 a 2018. A revisão da lista do Plano de Manejo resultou em 75 registros válidos. Destes, três espécies foram consideradas localmente extintas (Panthera onca, Tayassu pecari e Tapirus terrestris) e não foram incluídas na presente lista. Desse modo, listamos aqui 100 espécies com registros recentes no PARNASO, o que representa um acréscimo de 28 espécies. As ordens com maior riqueza de espécies foram Rodentia e Chiroptera, com 32 e 23 espécies, respectivamente. Das espécies registradas, quatro são invasoras (Callithrix jacchus, C. penicillata, Rattus norvegicus e R. rattus), três são domésticas (Bos taurus, Canis familiaris e Felis catus), e 26 são ameaçadas de extinção. A análise da distribuição espacial da riqueza de espécies mostrou que apenas metade da área do parque possui ao menos um registro, e que os registros estão concentrados onde há infraestrutura para a pesquisa. A presença de espécies domésticas e invasoras, bem como as extinções locais detectadas, indicam a necessidade de ações de manejo no interior do parque. Esse grande acréscimo de espécies à lista evidencia o desenvolvimento da pesquisa com mamíferos nesta Unidade de Conservação e a necessidade de compilações mais frequentes dos resultados devido aos vários projetos em curso. O PARNASO tem papel de destaque na conservação de mamíferos ao ainda manter uma das maiores riquezas de espécies do Estado do Rio de Janeiro, e grande importância para a pesquisa, abrigando uma ampla gama de estudos e projetos de longa duração.
We report the first record of homing behavior of a Neotropical marsupial, the opossum Philander f... more We report the first record of homing behavior of a Neotropical marsupial, the opossum Philander frenatus. The individual studied returned to the home forest fragment where it was captured (1050 m away) crossing a hostile matrix, instead moving to a much closer fragment (50 m distant). Movements did not follow wind or the direction of the closest fragment, but they were significantly oriented towards the home fragment. The individual probably had previous experience with the release site. This unique observation suggests that the ability of P. frenatus to overcome the effects of habitat fragmentation may be higher than considered previously. RESUMO: Comportamento de “homing” de Philander frenatus (Didelphimorphia, Didelphidae) em uma paisagem fragmentada da Mata Atlântica do Brasil. Relatamos o primeiro registro de comportamento de “homing” de um marsupial neotropical, Philander frenatus. O indivíduo estudado retornou para o fragmento onde foi capturado (distante 1050 m) atravessando...
We compare temporal variations in leaf fall among three sites of evergreen Atlantic Forest and an... more We compare temporal variations in leaf fall among three sites of evergreen Atlantic Forest and analyze how climatic variables influence it. Sites were located at Serra dos Órgãos National Park at different altitudes. Litter was collected monthly, from September 1997 to September 2005. Leaves were separated from other litter elements, oven-dried and weighted. Differences in leaf fall mass among grids and how they correlated with temporal variations were analyzed. Climatic variables were obtained from a nearby station and deviations from climatological normals were analyzed. We grouped climatic variables using Principal Component Analyses (PCA) and the highest scores of the two main factors were selected to construct regression models for different time lags. Leaf fall represented 50.5-70 percent of the total litter fall and mean leaf fall differed significantly among grids. However, leaf fall seasonality in the three areas were correlated. Leaf fall increased at the end of dry periods, when temperature and precipitation started to increase. Climatic variables were classified into two groups: seasonal and anomaly. Models constructed with lag variation from 0 and 6 months show that leaf fall was best explained by an anomaly in the maximum mean temperature, with lag 0, and by precipitation, with a six-month lag. We conclude that plant species respond immediately to drastic deviations from climatic factors, while regular climatic conditions are responsible for the seasonality of leaf fall, most likely as a late response to water shortage at the end of the dry season.
Climatic seasonality affects marsupial space use through changes in food, mate, and nest availabi... more Climatic seasonality affects marsupial space use through changes in food, mate, and nest availability. These effects can be enhanced when population size has an additive effect in the dry season. We tested if daily home range area and intensity of habitat use of the marsupial Metachirus nudicaudatus is affected by population size, climatic (dry and wet), and reproductive (breeding and non-breeding) seasons, and if it differs between genders. Metachirus nudicaudatus space use was affected by climatic seasonality, with individuals exploring larger areas in the dry season, probably in search for food. No effect of population size or differences in space use between sexes was detected. Further studies should test experimentally the effect of food availability on marsupials space use to confirm or rebut this hypothesis.
Recent studies suggest that habitat amount is the main determinant of species richness, whereas h... more Recent studies suggest that habitat amount is the main determinant of species richness, whereas habitat fragmentation has weak and mostly positive effects. Here, we challenge these ideas using a multi-taxa database including 2230 estimates of forest-dependent species richness from 1097 sampling sites across the Brazilian Atlantic Forest biodiversity hotspot. We used a structural equation modeling approach, accounting not only for direct effects of habitat loss, but also for its indirect effects (via habitat fragmentation), on the richness of forestdependent species. We reveal that in addition to the effects of habitat loss, habitat fragmentation has negative impacts on animal species richness at intermediate (30-60%) levels of habitat amount, and on richness of plants at high (> 60%) levels of habitat amount, both of which are mediated by edge effects. Based on these results, we argue that dismissing habitat fragmentation as a powerful force driving species extinction in tropical forest landscapes is premature and unsafe.
As florestas semidecíduas do interior do Estado de São Paulo são isoladas e pequenas devido às at... more As florestas semidecíduas do interior do Estado de São Paulo são isoladas e pequenas devido às atividades agrícolas, expansão urbana e industrial. Os remanescentes dos fragmentos florestais são importantes para a persistência de diversas espécies de mamíferos. Neste estudo foi feito um inventário da mastofauna de um fragmento de mata mesófila semidecídua no interior do Estado (Fazenda São José) nos municípios de Rio Claro e Araras. Nos três períodos amostrados, entre maio de 1997 e março de 1999, o levantamento da mastofauna foi feito por meio de armadilhas para pequenos mamíferos, bem como de observação direta e identificação de rastros dos animais. Registrou-se a ocorrência de três espécies de marsupiais (Didelphidae), duas de tatus (Dasipodidae), três de primatas (Callithrichidae e Cebidae), cinco de carnívoros (Canidae, Procyonidae e Mustelidae), uma de veado (Cervidae), sete de roedores (Sciuridae e Muridae) e uma de coelho (Leporidae). Didelphis albiventris (Didelphidae), Nect...
Oryzomyine rodents of Nectomys have a repertoire of swimming postural behaviors used in different... more Oryzomyine rodents of Nectomys have a repertoire of swimming postural behaviors used in different ecological aspects of its life, affecting key tasks of their survival. These species present three swimming behaviors: bipedal surface swimming, quadruped symmetric submerged swimming, and swimming bound, with correspondent differences in performance. Here we describe and measure the postural behavior in the swimming bound of Nectomys squamipes and N. rattus. Rodents were filmed at 30 frames s-1 in lateral view, swimming in a glass aquarium. Video sequences were analyzed dividing the swimming cycle into power and recovery phases. The two species did not differ in swimming behavior. Both species presented displacement of the head at vertical axis during impulsion, reaching its maximum displacement at the end of the phase. The power phase of the hindlimbs was primarily responsible for the animal propulsion. The flexion and extension of the head relative to the neck occurred in the impulsion and the recovery phase, respectively. During the hindlimbs power phase occurred the extension of the spine, raising the body of the animal above the water surface. The swimming bound allows a burst of speed and likely escape predation, hence involving specific postural behavior described here for the first time. These specific behaviors are related to morphological adaptations of spine, hindlimbs and feet, that allow spine extension and hindlimb thrust in an aquatic environment beyond the abilities of terrestrial rodents.
Medidas de desempenho utilizadas podem fornecer uma medida do nicho fundamental, permitindo preve... more Medidas de desempenho utilizadas podem fornecer uma medida do nicho fundamental, permitindo prever uso do habitat ou recursos na ausência de interações entre espécies. Propomos um conjunto padrão de testes de desempenho locomotor para vertebrados arborícolas, e um método para desenvolver modelos ecomorfológicos baseados em testes de desempenho e análise de caminhos. Os testes propostos simulam características do habitat como diâmetro e orientação de suportes. Modelos de relações entre variáveis podem ser formulados e comparados através da análise de caminhos, permitindo escolher o modelo de melhor ajuste aos dados. Este procedimento foi aplicado ao marsupial Philander frenata, comparando-se o efeito da forma corporal sobre o comprimento e freqüência de passadas no andar arborícola. O modelo incluindo caminhos tanto para freqüência como para comprimento de passadas teve um ajuste significativamente melhor que o modelo com caminhos apenas para o comprimento das passadas. Um modelo ger...
Differences in body size and in the use of arboreal strata limit the climbing behaviour and perfo... more Differences in body size and in the use of arboreal strata limit the climbing behaviour and performance of didelphids. Similarly to primates, the arboreal canopy dweller, Caluromys philander exhibits a diagonal-sequence gait. In contrast, terrestrial didelphids use a symmetrical lateral sequence in horizontal locomotion. Postural behaviour along thin supports may allow understanding the mechanisms behind the higher performance of arboreal didelphids climbing. Here in, we describe and compare gait sequence and postural behaviour of seven didelphids climbing a slender and flexible vertical support. Animals were stimulated to climb a vertical support of 1.25 cm diameter. Postural behaviour was qualitatively described for each species in the cycle of maximum velocity by a frame-by-frame analysis of gait cycles, evaluating (1) movements of the tail, (2) posture of hand and wrist when grasping, (3) distance of the body to the support, (4) lateral swinging of the body, (5) orientation of the head, (6) limb posture, and (7) stride cycle. Only arboreal species were capable of climbing with only two limbs grasping the support, keeping a straight body orientation at some distance from the support, and sustaining a more constant and regular climbing velocity. The tail played a role in didelphids with better climbing performance (i.e., higher relative velocity), counteracting the lateral swinging of the body, helping with the animal balance. However, the prehensile ability of the tail was not used in climbing. The most stunning result is that all didelphids grasped the rope between digits 2-3, a schizaxonic grasp, involving a neutral hand orientation regarding the ulna. The didelphids protracted the humerus at forelimb touchdown, and the angle between the arm and the horizontal body axis was greater than 90°. The same postures were already observed in horizontal locomotion of C. philander, Monodelphis domestica, and primates. Locomotory and postural adaptations for an arboreal lifestyle in didelphids seem to be limited to small to medium body sizes, up to the size of species of Caluromys. The arboreal locomotion of didelphids is an important key to understand adaptation and evolution of mammals to an arboreal niche, and the comparison with small primates may help to identify adaptive convergence to arboreal locomotion.
We study the population size time series of a Neotropical small mammal with the intent of detecti... more We study the population size time series of a Neotropical small mammal with the intent of detecting and modelling population regulation processes generated by density-dependent factors and their possible delayed effects. The application of analysis tools based on principles of statistical generality are nowadays a common practice for describing these phenomena, but, in general, they are more capable of generating clear diagnosis rather than granting valuable modelling. For this reason, in our approach, we detect the principal temporal structures on the bases of different correlation measures, and from these results we build an ad-hoc minimalist autoregressive model that incorporates the main drivers of the dynamics. Surprisingly our model is capable of reproducing very well the time patterns of the empirical series and, for the first time, clearly outlines the importance of the time of attaining sexual maturity as a central temporal scale for the dynamics of this species. In fact, an important advantage of this analysis scheme is that all the model parameters are directly biologically interpretable and potentially measurable, allowing a consistency check between model outputs and independent measurements.
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Papers by Marcus Vieira