Navegando por Assunto "Amazonia"

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Artigo
Cryptic diversity and historical biogeography of a nurse- frog species complex (Allobates tinae)
(Zoologica Scripta, 2024-12) Gabriela Farias Maia; Miquéias Ferrão; Leandro Moraes; Igor L. Kaefer; Albertina P. Lima
Amazonia continuously reveals outstanding biotic diversity and endemism, but our comprehension regarding their underlying processes has been impaired by knowledge gaps on cryptic taxonomic diversity. Here, we clarified the diversity and historical biogeography of nurse-frogs typical from Brazilian Southwestern Amazonia, the Allobates tinae species complex, using fine-scale population sampling and molecular-based analyses. Fieldwork was conducted at 23 localities across three major interfluves encompassing two well-recognized areas of endemism. Fragments of three mitochondrial DNA genes were sequenced and compared through phylogeographic and phylogenetic analyses. Based on these results, we estimated the species limits and inferred the historical biogeography. We found seven highly supported clades, which were considered as distinct species according to delimitation analyses. However, only two of these clades are taxonomically described, indicating a nearly threefold underestimation of the complex species richness. Major clades showed pronounced genetic distances, strong spatial structuring, and restricted or absent haplotype sharing. However, genetic structure was not predicted by geographic distance, and strong genetic structure among major clades was evident even at smaller geographical scales lacking evident physical barriers. Biogeographic analysis indicated diversification of the A. tinae complex most likely occurred through dispersals followed by speciations. These events started southward from the Guiana Shield during the Miocene, and were followed by sequential secondary northward dispersals along the Pliocene and Pleistocene. Our results indicate combined roles of historical (landscape dynamism) and ecological (environmental heterogeneity) factors driving biotic diversification in Brazilian Southwestern Amazonia.
Artigo
Habitat selection by Bothrops atrox (Serpentes: Viperidae) in central Amazonia, Brazil.
(Bioone, 2019-03-28) de Fraga, Rafael; Magnusson, William E.; Abrahão, Carlos R.; Sanaiotti, Tania; Lima, Albertina P.
Tropical rainforests often appear relatively homogeneous on satellite images, but responses to landscape characteristics may be found on finer scales if habitat characteristics are considered as continuous variables. In this study, we used 30 uniformly distributed plots and 16 plots beside streams to evaluate the effects of distance from stream, litter depth, altitude, slope, and tree density on abundance of Amazonian Lancehead Pitviper (Bothrops atrox). We estimated densities and probabilities of detection of snakes in riparian and upland plots in Reserva Ducke, Manaus, Amazonas,Brazil. Apparent density of individuals of B. atrox was about 6.4 times higher near streams, but the number of individuals in the landscape more than 10 m away from streams was about 3.9 times higher than the number of individuals within 10 m of streams. Movement data from two adult B. atrox evaluated by radio telemetry indicate that individuals can disperse out of plots and away from streams over a period of several months. Detectability of B. atrox varied little among riparian and upland plots, so differences in detectability are unlikely to be responsible for large differences in encounter rates of snakes between riparian and non-riparian areas. There were small differences in body size of individuals near streams and individuals far from streams. The distribution of B. atrox is not uniform within the forest. However, as with most other tropical-forest organisms studied to date, this species occurs across wide environmental gradients and shows only subtle habitat specificity.
Artigo
Tadpoles of the dyeing poison dart frog Dendrobates tinctorius (Cuvier, 1797) from eastern Amazonia
(2024-01-15) Ferrão, Miquéias; Dias, Pedro Henrique; Kaefer, Igor L.; Ferreira, Anthony; Tavares-Pinheiro, Rodrigo; Freitas, Abdiel Pinheiro; Campos, Carlos Eduardo Costa
The dendrobatid genus Dendrobates Wagler currently includes five species distributed from southern Nicaragua throughCosta Rica, Panama, and Colombia to the Guianas and adjacent Brazil (Frost 2023). Two species are found in Brazil:Dendrobates leucomelas Steindachner and D. tinctorius (Cuvier). The latter was originally described from “Amérique”,and a neotype was designed by Silverstone (1975) from the Rivière Matarony, French Guiana. In Brazil, it is found inthe States Amapá and Pará (Avila-Pires et al. 2010; Taucce et al. 2022). It is a diurnal species that inhabits the leaf litterof rainforests, and exhibits polymorphism with various distinct post-metamorphic color patterns (Rojas & Pašukonis2019). Due to its popularity in the pet trade it is listed under Appendix II of CITES. Adults deposit clutches in the leaflitter, typically containing 2–14 eggs that hatch within 14–28 days. Males then transport the tadpoles to small waterbodies, e.g., palm bracts, bromeliads, or tree holes (Born 1994; Born et al. 2010; Rojas & Pašukonis 2019). Tadpoleshave a varied diet, including detritus, insect larvae and other tadpoles, often conspecific. Metamorphosis typically occursbetween 90 and 120 days after oviposition (Masurat & WolfRudiger 1991; Born 1994; Rojas & Pašukonis 2019). Theexternal morphology of a tadpole from the western slope of Vier Gebroeders Mountain in Surinam was briefly describedby Hoogmoed (1969) as D. azureus Hoogmoed, which is now considered a synonym of D. tinctorius (Wollenberg et al.2008). Silverstone (1975) provided additional descriptions and illustrations of the body and oral apparatus of specimensfrom Serra do Navio (Amapá, Brazil). Lescure (1984) provided a draft of the oral apparatus and body, but without anymorphological description. Finally, the chondrocranium morphology of these tadpoles was described by Haas (2003).Despite previous studies addressing the external morphology of D. tinctorius larvae, there are still several aspects thathave not been adequately described, and some character-states require further examination. Thus, in the present study, theexternal morphology of D. tinctorius is redescribed following current standards for larval descriptions.