TARÁNTULAS (Araneae: Theraphosidae) DE LA CUENCA MEDIA DEL PUTUMAYO, LORETO, PERÚ.

Theraphosidae represent the family with the greatest diversity in the Mygalomorphae suborder, but the scarcity of studies in the Peruvian Amazon has generate uncertainty about its richness, reason that encourages to determine the species of tarantulas located the middle basin of the Putumayo river (Peru). Sampling was carried out in two communities: Puerto Arturo and Bobona, riparian populations, along pre-established transects and occasional manual collecting outside the transects; allspecimens were identified using taxonomic keys, descriptions and information available on web pages. Ten individuals were recorded, distributed in seven species, three belonging to the subfamily Theraphosinae, two to Avicularinae, one to Ischnocolinae and one to Psalmonpoeinae. This work aims to presents preliminary results of the diversity of tarantulas in the Putumayo river basin in indicating. The presence of least seven species in four subfamilies.Los Theraphosidae son la familia con mayor diversidad en los Mygalomorphae, pero la escasez de estudios en la Amazonía peruana ha generado una incertidumbre sobre ellos, por lo que tuvimos el objetivo de determinar las especies de tarántulas que se encuentra en la cuenca media del Putumayo (Perú). El muestreo se realizó en dos comunidades:  Puerto Arturo y Bobona, a través de recorridos en transectos preestablecidos y encuentros ocasionales fuera de los transectos; los especímenes se identificaron mediante claves taxonómicas especializadas, descripciones e información disponible en catálogos en línea. Se registraron 10 individuos, distribuidas en 7 especies, 3 pertenecientes a la subfamilia Theraphosinae, 2 a Aviculariinae, 1 a Ischnocolinae y 1 a Psalmopoeinae. Este trabajo presenta la primera aproximación sobre la diversidad de tarántulas para la cuenca del Putumayo en Perú. Demostrando la presencia de 7 especies en 4 subfamilias

Área foliar de Caraipa utilis Vásquez en un varillal de la Reserva Nacional Allpahuayo Mishana, Loreto, Perú

Se determinó un modelo matemático para estimar el área foliar de Caraipa utilis Vásquez en base al largo y ancho de la lámina foliar en el Bosque sobre arena blanca de la Reserva Nacional Allpahuayo Mishana. Se realizó el inventario de los individuos mayores a 10 cm de DAP de Caraipa utilis Vásquez en 1 ha. Después se seleccionó al azar 10 árboles, colectándose 50 hojas/árbol, evaluando al largo, ancho y largo por ancho. El largo promedio fue de 74,95 mm, con un ancho promedio de 32,55 mm. El área foliar calculada fue 1474,64 mm2, lo cual corresponde al tipo macrófila. Se desarrolló dos modelos matemáticos: El modelo lineal (AF = 281,757 + 0,473284 LxA, R2 = 0,774), sugerido para investigaciones que no requieran un grado de precisión elevado en la estimación de los datos. El segundo modelo es el cuadrático (AF = 63,205 + 0,63066 LxA – 0,0000238549 LxA2, R2 = 0,783), recomendado en investigaciones que requieran mayor precisión en la obtención de datos. Los modelos propuestos son válidos para esta especie, ya que tienen precisión, son prácticos y fáciles de medir, pero la elección del modelo a utilizar, dependerá del criterio del investigador y el propósito del estudio

Plantas consumidas por Lagothrix lagotricha lagotricha Humboldt, 1812 en la Amazonía peruana

Lagothrix lagotricha lagotricha es una especie bioindicadora de la Amazonía, forma parte de la dieta de las comunidades indígenas, gente rural y urbana. L. l. lagotricha cumple una función ecológica como dispersor de semillas, por eso es importante conocer qué ítems y especies vegetales consume en esta parte de la Amazonía. En este estudio se identificaron las especies de plantas y partes de las plantas consumidas por L. l. lagotricha en un bosque tropical primario, al margen izquierdo del río Lagartococha, al noreste del Perú, en el Parque Nacional Güeppí-Sekime (PNGS). Se observó a la especie durante 485 horas desde junio a setiembre del 2017. Se identificaron 20 ítems vegetales, incluidos en 8 grupos vegetales: hoja, fruto, infrutescencia, flor, inflorescencia, resina, raíz y tallo; siendo las más importantes: mesocarpo 26,28%, hoja completa 26,28%, endocarpo 10,22% y semilla 9,49%, así como también, un total de 109 especies de plantas, agrupadas en 42 familias, de los cuales las familias más consumidas fueron: Arecaceae, Fabaceae y Araceae. Esta primera investigación, aporta en la comprensión de la dieta alimenticia y las especies de plantas consumidas por L. l. lagotricha, los cuales, nos dan un alcance del papel ecológico de la especie en la estructura del bosque amazónico. Además, esta investigación puede ser utilizada como base para el inicio de otras investigaciones, como estudios de dispersión y depredación de semillas

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R$^{2}$ = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R$^{2}$ = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

The biogeography of the Amazonian tree flora

We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Withinplot species composition reflected both local environmental conditions (especially soil nutrients and hydrology) and geographical regions. A broader-scale view of species turnover was obtained by interpolating the relative tree species abundances over Amazonia into 47,441 0.1-degree grid cells. Two main dimensions of spatial change in tree species composition were identified. The first was a gradient between western Amazonia at the Andean forelands (with young geology and relatively nutrient-rich soils) and central–eastern Amazonia associated with the Guiana and Brazilian Shields (with more ancient geology and poor soils). The second gradient was between the wet forests of the northwest and the drier forests in southern Amazonia. Isolines linking cells of similar composition crossed major Amazonian rivers, suggesting that tree species distributions are not limited by rivers. Even though some areas of relatively sharp species turnover were identified, mostly the tree species composition changed gradually over large extents, which does not support delimiting clear discrete biogeographic regions within Amazonia

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe