ABSTRACT. STRUCTllRAL IIETEROGENErrV AI"D DIVERsrrv OI' SMALL MAMMAL~IN A SECONDARY FOREsr FRAGMENTOF MINAS GERAIS. BRASIL. The aim is lo delermine lhe rclalionship helween lhe diversily of small mammals and the slructural helerogeneity and/or seeondary suceessional slages in an Atlantic foresl fragment aI Viçosa (Minas Gerais). We used Sherman and hook live traps lo sample this fauna, monthly from may 1992 to april 1993 in lhree arcas: an ahandoned planlation of Melinis mil1llliJInra (campo) and lwo distincl forest arcas (capoeira and mala). The slruelural hclerogeneily was delermined as a funclion of lhe presence of dead lrees. pioneer species. epiphytes. lhe distances helween trees. lhe lree heighl and bas.11 area measured hy a modified quadrant sample melhod (ConAM & CURTtS 1945). It was sampled a lotai of 340 individuais bclonging to 17 species. The homogeneous plantalions had the highesl diversily (H" = 1.67). Among lhe lWO foresls stands lhe lcss helerogeneous capoeira had similar diversity (H" = 1.19) lhan lhe more helerogeneous stand. lhe mala (H' = 1.13). The unexpected higher diversily and species richness in lhe more homogeneous habitat may he explained hy some hidden faclor which decrease lhe compclilion for resources in lhis communily. KEY WORDS. Con1lnunily slrueture. habilal helerogeneily. small man1lnal divcrsity A grande diversidade de espécies observada nos Trópicos Úmidos pode ser correlacionada com a relativa estabilidade climática (KARR & ROTH 1971) e com a alta produtividade primária (PIANKA 1967). Entretanto, o padrão de biodiversidade faunística vem sendo alterado pelo crescente desenvolvimento econômico das regiões tropicais (WILSON 1988) que tem como resultado a fragmentação dos sistemas tlorestais dessas regiões.A Floresta Atlântica Brasileira é um dos ecossistemas em que as conseqüên-cias desse processo de colonização podem ser melhor visualizadas. Acredita-se que menos de I % da Mata Atlântica permanece em sua forma não-perturhada
Abstract. Our understanding of mammal ecology has always been hindered by the difficulties of observing species in closed tropical forests. Camera trapping has become a major advance for monitoring terrestrial mammals in biodiversity rich ecosystems. Here we compiled one of the largest datasets of inventories of terrestrial mammal communities for the Neotropical region based on camera trapping studies. The dataset comprises 170 surveys of medium to large terrestrial mammals using camera traps conducted in 144 areas by 74 studies, covering six vegetation types of tropical and subtropical Atlantic Forest of South America (Brazil and Argentina), and present data on species composition and richness. The complete dataset comprises 53,438 independent records of 83 species of mammals, includes 10 species of marsupials, 15 rodents, 20 carnivores, eight ungulates and six armadillos. Species richness averaged 13 species (AE6.07 SD) per site. Only six species occurred in more than 50% of the sites: the domestic dog Canis familiaris, crab-eating fox Cerdocyon thous, tayra Eira barbara, south American coati Nasua nasua, crab-eating raccoon Procyon cancrivorus and the nine-banded armadillo Dasypus novemcinctus. The information contained in this dataset can be used to understand macroecological patterns of biodiversity, community, and population structure, but also to evaluate the ecological consequences of fragmentation, defaunation, and trophic interactions.
AbstractAkodontini, the second largest tribe within sigmodontine rodents, encompasses several stomach morphologies. This is striking because most sigmodontine groups of comparable taxonomic rank are very conservative in this respect. Based on extensive sampling of newly dissected specimens (213 stomachs representing 36 species), as well as published examples, covering almost all akodontine living genera (15 of 16), we undertook a reappraisal of the gross morphology of this organ. We then mapped this information, together with gallbladder occurrence, in a refined multilocus molecular phylogeny of the tribe. We surveyed three different configurations of stomachs in akodontines, according to the degree of development and location of the glandular epithelium; in addition, two minor variations of one of these types were described. Of the five major clades that integrate Akodontini, four are characterized by a single stomach morphology, while one clade exhibits two morphologies. Mapping stomach type on the phylogeny recovered two configurations for the most recent ancestor of Akodontini. A revised survey of gallbladder evidence also revealed overlooked congruencies. The observed stomach diversity and its arrangement in the phylogeny, along with additional morphological characters and the genetic diversity among the main clades, supports the necessity of changes in the current classification of the tribe. Recognition of subtribes or partitioning of Akodontini into several additional tribes of equal rank could be suitable options.
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