Variation in the food-niche width of Gracilinanus microtarsus (Didelphimorphia: Didelphidae) in a cerrado remnant in south-eastern Brazil

Martins, Eduardo Gomes; Bonato, Vinícius; Pinheiro, Aluísio; Reis, Sérgio Furtado dos

doi:10.1016/j.mambio.2006.03.001

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…Increased isolation due to the reduction in the number of immigrants might also affect genetic diversity [61] , [62] . In an investigation of genetic diversity in functional markers (Major Histocompatibility Complex, MHC) in the 30% forest cover landscape, Meyer-Lucht et al [63] , [64] found surprisingly low numbers of alleles and associated higher parasite loads in populations of M. incanus compared to a sympatric didelphid marsupial, Gracilinanus microtarsus , which also occupies savanna-like habitats [65] , [66] , and is considered less dependent on forest. Furthermore, a study on genetic variation based on non-functional markers (microsatellites) of populations of M. incanus in the same two landscapes found lower genetic diversity in populations of the less forested landscape (30%) as expected when dispersal between populations is reduced (Balkenhol, N., unpublished data ).…”

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confidence: 99%

Immigration Rates in Fragmented Landscapes – Empirical Evidence for the Importance of Habitat Amount for Species Persistence

et al. 2011

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BackgroundThe total amount of native vegetation is an important property of fragmented landscapes and is known to exert a strong influence on population and metapopulation dynamics. As the relationship between habitat loss and local patch and gap characteristics is strongly non-linear, theoretical models predict that immigration rates should decrease dramatically at low levels of remaining native vegetation cover, leading to patch-area effects and the existence of species extinction thresholds across fragmented landscapes with different proportions of remaining native vegetation. Although empirical patterns of species distribution and richness give support to these models, direct measurements of immigration rates across fragmented landscapes are still lacking.Methodology/Principal FindingsUsing the Brazilian Atlantic forest marsupial Gray Slender Mouse Opossum (Marmosops incanus) as a model species and estimating demographic parameters of populations in patches situated in three landscapes differing in the total amount of remaining forest, we tested the hypotheses that patch-area effects on population density are apparent only at intermediate levels of forest cover, and that immigration rates into forest patches are defined primarily by landscape context surrounding patches. As expected, we observed a positive patch-area effect on M. incanus density only within the landscape with intermediate forest cover. Density was independent of patch size in the most forested landscape and the species was absent from the most deforested landscape. Specifically, the mean estimated numbers of immigrants into small patches were lower in the landscape with intermediate forest cover compared to the most forested landscape.Conclusions/SignificanceOur results reveal the crucial importance of the total amount of remaining native vegetation for species persistence in fragmented landscapes, and specifically as to the role of variable immigration rates in providing the underlying mechanism that drives both patch-area effects and species extinction thresholds.

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Section: Discussionmentioning

confidence: 99%

Immigration Rates in Fragmented Landscapes – Empirical Evidence for the Importance of Habitat Amount for Species Persistence

et al. 2011

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“…Durante o período reprodutivo, as fêmeas necessitam de energia excedente para amamentar e cuidar da prole(Galindo-Leal & Krebs 1998; Martins et al 2006a, b). comumente reportados inclusive para entre didelfídeos(Pulliam 1986;Pinheiro et al 2002a;Martins et al 2006c). É predito pela teoria da dieta ótima que quando osrecursos são contrário seria esperado caso a ampliação do nicho trófico fosse resultado da ampliação dos nichos individuais.…”

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Nicho trofico de Micoureus paraguayanus (Didelphimorphia: Didelphidae)

Pires¹

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Ao meu orientador Sérgio Furtado dos Reis por estar sempre disponível para discutir e conversar sobre tudo incluindo o projeto. Ao meu co-orientador Prof. Dr. Paulo R. Guimarães Jr. pelo auxílio no projeto e por estar sempre disposto a ajudar. Aos colegas Drs. Eduardo G. Martins e Márcio S. Araújo que contribuíram em diversas partes desse projeto e também em minha formação. Ao Prof. Dr. Arício Xavier Linhares pela ajuda na identificação de invertebrados. Ao Prof. Jorge Yoshio Tamashiro pela ajuda na identificação de sementes. Aos membros da banca examinadora por aceitar prontamente participar, em especial à Profa. Dra. Eleonore Z. F. Setz pela orientação nos primeiros anos da graduação. À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) pela concessão das bolsas de iniciação científica e mestrado que permitiram a realização do projeto. Aos meus pais, Luiz e Tânia, minha irmã, Bárbara, e demais familiares pelo apoio em todas as minhas decisões. Aos amigos pelo suporte dentro e fora da Universidade. À Maria Carolina B. Grassi por estar sempre presente.iv SUMÁRIO Introdução Geral Objetivos Gerais Área de estudo Análise de composição da dieta Capítulo 1: 1.1. Introdução 1.2. Objetivos 1.3. Materiais e Métodos 1.4. Resultados 1.5. Discussão Capítulo 2: 2.1. Introdução 2.2. Objetivos 2.3. Materiais e métodos 2.3.1. Os componentes do nicho trófico populacional 2.3.2. Índice PSi de proporção de similaridade 2.3.3. Índice E de variação interindividual 2.3.4. Teste de significância dos índices de variação na dieta 2.3.5. Teste da qualidade dos dados 2.4. Resultados 2.4.1. Qualidade dos dados 2.4.2. Variação intrapopulacional e interindividual no nicho trófico 2.5. Discussão Capítulo 3 3.1. Introdução 3.2. Objetivos 3.3. Materiais e métodos 3.3.1. Redes indivíduo-recurso 3.3.2. Modularidade 3.3.3. Aninhamento 3.4. Resultados 3.5. Discussão Conclusões Gerais Literatura citada v

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Seasonal dynamics with compensatory effects regulate populations of tropical forest marsupials: a 16-year study

et al. 2016

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The conditions that a population experiences during one season can affect the strength of density dependence in the following season. In the tropics, many populations face their biggest challenges in the dry season due to limited food and cold-dry conditions. Seasonal environmental changes can be especially problematic for small, short-lived, seasonally breeding endotherms. To investigate the effects of seasonality on population dynamics, we studied five marsupial species in the Brazilian Atlantic Forest, using a 16-year dataset. We tested if (1) compensatory density feedback is stronger in the dry season, due to the high population sizes and limited food; (2) lower temperatures and the overall abundance of small mammals negatively affect dry season population growth rates; and (3) rainfall, a proxy for food availability, is positively related to wet season population growth rates. Population growth rates were regressed against seasonal population sizes and exogenous variables, and analyzed with linear autoregressive models. Seasonal compensatory density feedback occurred in both seasons, with compensation processes in just one season being sufficient to allow population persistence. Rainfall and the overall abundance of small mammals had little influence on populations, while colder temperatures decreased population growth rate of smaller species in both seasons. Although the study marsupials share similar life histories and phylogeny, they varied with respect to the season when compensatory density feedback was strongest. Our results demonstrate that seasonality plays a key role in driving marsupial population dynamics, and highlight the need to account for seasonality in demographic studies even in tropical environments.

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Variation in the food-niche width of Gracilinanus microtarsus (Didelphimorphia: Didelphidae) in a cerrado remnant in south-eastern Brazil

Cited by 4 publications

References 18 publications

Immigration Rates in Fragmented Landscapes – Empirical Evidence for the Importance of Habitat Amount for Species Persistence

Immigration Rates in Fragmented Landscapes – Empirical Evidence for the Importance of Habitat Amount for Species Persistence

Nicho trofico de Micoureus paraguayanus (Didelphimorphia: Didelphidae)

Seasonal dynamics with compensatory effects regulate populations of tropical forest marsupials: a 16-year study

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