Gracilinanus microtarsus (Didelphimorphia: Didelphidae)

Gracilinanus microtarsus (J. A. Wagner, 1842), called the Brazilian gracile opossum, is a small didelphid that is 1 of 6 species in the genus Gracilinanus. It is a sexually dimorphic, solitary marsupial that has a highly seasonal reproductive pattern. It inhabits Atlantic rain forests and semideciduous forests interspersed in the highly seasonal cerrado (savanna-like vegetation) in southeastern and southern Brazil. It prefers locations associated with low canopy cover and it also occurs in habitats altered by anthropogenic events. The species is classified as Least Concern by the International Union for Conservation of Nature and Natural Resources. © 25 March 2010 by the American Society of Mammalogists

Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction

The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.We thank D. M. Hansen, P. Jordano and two anonymous reviewers for critical suggestions regards the manuscript. M. M. P., M. G. and P. R. G. were supported by São Paulo Research Foundation (FAPESP; grant nos. 2009/54422-8, 2004/00810-3, 2008/10154-7, and 2009/54567-6). C. I. D. was supported by Stanford University. M. G ., P. R . G . and M. A . P. receive research grants from CNPq. We also thank the Earthwatch Institute and Conservation International for financial support and Conservation International, Lucas Leuzinger and Marina Schweizer for their permission to work on their properties

Subpathotypes of Avian Pathogenic Escherichia coli (APEC) Exist as Defined by their Syndromes and Virulence Traits

Avian pathogenic Escherichia coli (APEC) strains cause different types of systemic extraintestinal infections in poultry, collectively termed colibacillosis, which can cause significant economic losses in the poultry industry. To date, there have been no descriptions of genes or characteristics that allow for the classification of avian strains pathotypes responsible for causing specific diseases in their hosts. In this study we aimed to characterize avian E. coli strains representing 4 groups, including one of commensal strains (AFEC – Avian Fecal Escherichia coli) and 3 groups of APEC strains, where each group is responsible for causing a different disease syndrome in their respective hosts (septicemia, omphalitis and swollen head syndrome). We chose to examine several biological characteristics of these strains including: adhesion to eukaryotic cells, pathogenicity levels according to the lethal dose (50%) assay, phylogenetic group and virulence gene profiles. The comparison of strains based on these genotypic and phenotypic traits, using multivariate statisticals tools and complex networks, allowed us to infer information about the population structure of the studied groups. Our results indicate that APEC strains do not constitute a unique homogeneous group, but rather a structured set of subgroups, where each one is associated with a specific infectious syndrome which can possibly be used to define pathotypes or subpathotypes within APEC strains. These results offer new possibilities with which to study the genes responsible for various pathogenetic processes within APEC strains, and for vaccine development. It may be important to consider these subgroups when developing a vaccine in an effort for obtain cross protection, which has not yet been successfully accomplished when working with APEC strains

Rewilding ecological communities and rewiring ecological networks

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESRewilding encompasses management actions such as reintroductions and translocations with the purpose of restoring ecological processes and ecosystem functions that were lost when species were locally extirpated. The success of a species introduction is co154257265FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES2013/22016-6sem informaçãoI thank Paulo R. Guimarães and Tiago B. Quental for comments and suggestion

Trophic niche of Micoureus paraguayanus (Didelphimorphia: Didelphidae) : intra-population and inter-individual variation

Orientadores: Sergio Furtado dos Reis, Paulo Roberto Guimarães JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: A teoria do nicho como originalmente concebida baseia-se na pressuposição que os indivíduos de uma espécie ou população são ecologicamente equivalentes. Entretanto fatores endógenos e exógenos podem contribuir para a existência de variação nas dimensões do nicho. Nesse contexto foi estudada a ecologia alimentar do marsupial Micoureus paraguayanus em uma área de Cerrado com o objetivo de identificar os fatores endógenos e exógenos que influenciam na sua dieta e os padrões de subdivisão do nicho trófico populacional entre os indivíduos da população. A composição da dieta e a amplitude do nicho trófico foram fortemente influenciadas pela sazonalidade, havendo ainda diferenças relacionadas aos sexos no uso de recursos. No período de escassez de recursos alimentares, durante a estação fria?seca, houve ampliação do nicho trófico populacional devido ao aumento da variação interindividual na dieta. Essa variação resulta na ocorrência de indivíduos com dietas mais restritas compostas por subconjuntos do espectro de recursos usado pelos indivíduos com dietas menos restritas. Esses resultados adicionam M. paraguayanus a uma lista crescente de espécies onde tem sido demonstrada variação no uso de recursos e relatam a emergência de estrutura nas interações tróficas no nível dos indivíduos da população, abrindo caminho para uma nova área de interesse em ecologia alimentarAbstract: Niche theory as originally formulated is based upon the assumption that the individuals within a species or population are ecolgically equivalent. However endogenous and exogenous factors may contribute to the existence of variation in niche dimensions. In this context, I studied the feeding ecology of the didelphid marsupial Micoureus paraguayanus in a Cerrado (savannah-like) remnant with the objective of identifying the factors that affect its diet and the patterns of trophic niche subdivision amongthe individuals within the population. The dietary composition and trophic niche width were highly affected by seasonality with differences in resource use related o sex. In the cool?dry season, when resources are scarcer, niche was broader due to increased interindividual diet variation. This variation results in the occurrence of individuals with different degrees of diet generalization within the population sch that individuals with more constrained diets use subsets of the resource spectrum used by those individuals with broader dies. These results add M. paraguayanus to a growing list of species showing interindividual diet variation and show the emergence of structure in the trphic interactions at the individual?level, creating new avenues for future research in feeding ecologyMestradoMestre em Ecologi

Pleistocene trophic networks: structure and fragility

A extinção de grandes mamíferos terrestres no final do Pleistoceno (entre 50 e 11 mil anos atrás) é um dos temas mais debatidos em ecologia. A maioria dos estudos sobre as causas das extinções do Pleistoceno tem como foco o papel de fatores externos como mudanças climáticas e a chegada do homem. Entretanto, a forma como uma comunidade ecológica responde a perturbações depende de suas propriedades, como o número e composição de espécies e a forma como essas espécies interagem. O objetivo final dos estudos reunidos nessa tese foi entender como estavam organizadas as interações ecológicas entre os mamíferos do Pleistoceno e o possível papel dessas interações no episódio de extinção da megafauna. Em primeiro lugar adaptei modelos de teias tróficas para reproduzir redes formadas por diferentes tipos de interações entre consumidores e recursos. Em seguida, utilizei esses modelos para reconstruir redes de interação entre predadores e presas da megafauna do Pleistoceno e examinei as propriedades estruturais e dinâmicas dessas redes. Por fim, investiguei uma das possíveis consequências da extinção da megafauna: a perda de serviços de dispersão de sementes. Os resultados aqui apresentados mostram que (i) diferentes tipos de redes de interação entre consumidores e recursos compartilham características estruturais e podem ser reproduzidas por modelos de teias tróficas; (ii) redes de interação entre grandes mamíferos do Pleistoceno estavam, provavelmente, estruturadas de forma similar aos sistemas atuais na África. Entretanto, as comunidades do Pleistoceno seriam especialmente vulneráveis às mudanças estruturais e na dinâmica causadas pela chegada de um predador como o homem; (iii) entre as consequências da extinção do Pleistoceno está a reorganização de outros tipos de rede de interação como as redes de dispersão de sementes. Em conjunto os resultados apresentados aqui enfatizam a importância de considerarmos o possível papel das interações ecológicas em modular os efeitos de perturbações ao estudarmos eventos de extinçãoThe extinction of large terrestrial mammals during the late Pleistocene (between 50 and 11 kyrs ago) is one of the most debated topics in ecology. Most studies on the causes of Pleistocene extinctions focus on the role of external factors such as climate changes and the arrival of humans. Nevertheless, the way an ecological community responds to perturbations depends on its properties, such as its number of species, species composition and the way these species interact. This thesis encloses studies with the final objective of understanding how ecological interactions between Pleistocene large mammals were organized and the potential role of such interactions in the Pleistocene extinction episode. First, I adapted food-web models to reproduce networks depicting different types of ecological interactions between consumers and resources. Then, I used these models to reconstruct predator-prey interaction networks between Pleistocene large mammals and examined the structural and dynamic properties of these systems. Finally, as an overview of the ecological impacts of Pleistocene extinctions, I discuss one of the possible consequences of the demise of Pleistocene large mammals: the loss of seed-dispersal services. The results presented here show that (i) different types of interaction networks between consumers and resources share structural properties and can be reproduced by food-web models; (ii) interactions between Pleistocene large mammals were most likely structured in a similar way to modern large-mammals assemblages in Africa, but the former were especially vulnerable to the changes in structure and dynamics caused by a newly arriving predator such as humans; (iii) among the consequences of Pleistocene extinctions is the reconfiguration of other types of interaction networks such as seed-dispersal networks. Taken together these findings emphasize how important it is to consider the role of ecological interactions in modulating the effects of perturbations when studying extinctions event

Niche partitioning and coexistence of two spiders of the genus Peucetia (Araneae, Oxyopidae) inhabiting Trichogoniopsis adenantha plants (Asterales, Asteraceae).

Niche theory suggests that the coexistence of ecologically similar species in the same site requires some form of resource partitioning that reduces or avoids interspecific competition. Here, from July 2013 to December 2015, we investigated spatial niche differentiation at three different scales of two sympatric congeneric spiders, Peucetia rubrolineata and P. flava, along an altitudinal gradient in shaded and open areas in an Atlantic forest in Serra do Japi, SP, Brazil. These spiders are peculiar in that they present an exclusive association with the plant Trichogoniopsis adenantha (Asteraceae). In theory, the coexistence of two Peucetia species could be explained by: (1) microhabitat segregation with individuals from different species occupying different parts of the same plants; (2) mesohabitat segregation with different species using plant in different environments; (3) macrohabitat segregation, where different species would not co-occur along the altitudinal gradient. With respect to micro-habitat use, in both species, different instars used different plant parts, while the same instars of both species used the same type of substrate. However, the two Peucetia species segregated by meso-habitat type, with P. rubrolineata preferring T. adenantha plants in shaded areas and P. flava preferring those in open areas. Our results support the hypothesis of niche partitioning begetting diversity, and highlight the importance of analyzing habitat use at multiple scales to understand mechanisms related to coexistence

Data from: Geographical and intrapopulation variation in the diet of a threatened marine predator, Pontoporia blainvillei (Cetacea)

Diet variation can occur in geographically structured populations due to variation in prey availability. Within locations, diet may vary due to effects of season, sex, age, and individual. Nevertheless, these sources of variation are seldom considered together in dietary studies. Major efforts are underway to investigate population and ecological traits of marine organisms to set guidelines for conservation and management. Examining diet variation is a major concern when developing conservation guidelines for threatened species, especially for marine predators whose prey availability can be reduced by commercial fisheries. We analyzed diet variation at the geographical and intrapopulation levels for detecting stocks of the franciscana dolphin (Pontoporia blainvillei) within São Paulo State coast. We analyzed samples of stomach contents of individuals incidentally caught by artisanal fisheries. We investigated the geographical (Northern, Central, and Southern regions of São Paulo State coast, Brazil) and intrapopulation effects of season, sex, and age. We used the leave-one-out cross validation method to test for significance of the proportional similarity index, which measures the overlap between diet compositions. We found diet variation in the franciscana dolphin across different levels, from the geographical to the individual level, including the effects of season, sex, and age. Diet variation as a function of age suggests an ontogenetic diet shift for the species. Our findings indicate that ecological processes within local stocks must drive management actions at local geographic scales. Evidence for ecological differences between franciscana stocks is of great significance for the conservation of this threatened species

Before, during and after megafaunal extinctions: Human impact on Pleistocene-Holocene trophic networks in South Patagonia

Worldwide extinctions of large terrestrial vertebrates in the late Pleistocene provide insight on how humans reshape ecological communities. Understanding the ecological causes and consequences of megafaunal extinctions requires integrating approaches to reconstruct the ecological communities from the past. Here, we combined archeological and paleontological evidence with network analyses to understand the changes in ecological communities from late Pleistocene to the Holocene in South Patagonia, the last continental region where the encounter between humans and extinct megafauna occurred. The zooarcheological record suggests humans would have interacted mainly with large-bodied species, which comprise a small subset of the available prey. Accordingly, using network reconstructions and structural analyses, we found that human arrival would have produced minor changes in the overall structure of trophic networks. However, those few novel interactions established by humans would have created multiple indirect paths among megafaunal species. Indirect paths are the route for indirect effects such as competition and increase the vulnerability of interaction networks to perturbations. After the extinctions of most of the megafauna, the impoverished network became structurally simpler and densely connected. Our reconstructions of past trophic networks show that multiple indirect effects, potentially contributing to extinctions, can emerge even from a limited number of novel interactions and illustrate how network organization can affect and be affected by extinctions events.Fil: Pires, Mathias Mistretta. Universidade Estadual de Campinas; BrasilFil: Rindel, Diego Damian. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Moscardi, Bruno Federico. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Antropología; ArgentinaFil: Cruz, Livia R.. Universidade Estadual de Campinas; BrasilFil: Guimaraes, Paulo Roberto. Universidade de Sao Paulo; BrasilFil: dos Reis, Sergio F.. Universidade Estadual de Campinas; BrasilFil: Perez, Sergio Ivan. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin