RESUMO
Resumen Introducción: La biodiversidad se está perdiendo a un ritmo acelerado como resultado del cambio global. Herramientas como los modelos de distribución de especies (MDEs) han sido ampliamente usados para mejorar el conocimiento sobre el estado de conservación de las especies y ayudar a desarrollar estrategias de gestión para mitigar la pérdida de biodiversidad. Objetivo: Determinar cómo la distribución potencial predicha por los MDEs para ocho especies de murciélagos amenazados difiere de los mapas de distribución reportados por la UICN. También, inferir el área de distribución y estado de endemismo de cada especie, y evaluar la importancia de la región tumbesina para su conservación. Métodos: Basados en registros de presencia del rango global de las especies, usamos MDEs para evaluar el estado de conservación de estas ocho especies en la región tumbesina de Ecuador y Perú. Resultados: Las áreas estimadas por los MDEs eran 35-78 % más pequeñas para cuatro especies (Eptesicus innoxius, Lophostoma occidentale, Platalina genovensium y Lonchophylla hesperia) y 26-1 600 % más grandes para tres especies (Amorphochilus schnablii, Promops davisoni y Rhogeessa velilla) que aquellas reportadas por la UICN. Para Tomopeas ravus, el área estimada por el MDE y la UICN fue similar, pero difirió en la distribución espacial. Los MDEs coincidieron con áreas de endemismo informadas por autores previos para E. innoxius, R. velilla y T. ravus, pero fueron diferentes para A. schnablii, P. genovensium, P. davisoni y L. hesperia, debido en parte a las distribuciones proyectadas para estas últimas especies en valles secos interandinos según los MDEs. Conclusiones: La región tumbesina representa una porción significativa (40-96 %) de la distribución predicha de siete de las ocho especies estudiadas, subrayando la importancia de esta región para la conservación de murciélagos. Nuestros resultados muestran las probables distribuciones para estas especies y proporcionan una base importante para identificar vacíos de investigación y desarrollar medidas de conservación para murciélagos amenazados en el punto caliente de biodiversidad de Tumbes.
Abstract Introduction: Biodiversity is being lost at an accelerating rate because of global change. Tools such as species distribution models (SDMs) have been widely used to improve knowledge about species' conservation status and help develop management strategies to mitigate biodiversity loss. SDMs are especially important for species with restricted distributions, such as endemic species. Objective: To determine how potential distribution predicted by SDMs for eight threatened bat species differed from the distribution maps reported by the IUCN. Also, to infer the area of distribution and state of endemism of each specie, and to evaluate the importance of the Tumbesian region for their conservation. Methods: Based on presence records across the species' entire ranges, we used SDMs to assess the conservation status of these eight species in the Tumbesian region of Ecuador and Peru. Results: The areas estimated by SDMs were 35-78 % smaller for four species (Eptesicus innoxius, Lophostoma occidentale, Platalina genovensium and Lonchophylla hesperia) and 26-1 600 % larger for three species (Amorphochilus schnablii, Promops davisoni and Rhogeessa velilla) than those reported by the IUCN. For Tomopeas ravus, the area estimated by the SDM and IUCN was similar but differed in spatial distribution. SDMs coincided with areas of endemism reported by previous authors for E. innoxius, R. velilla, and T. ravus, but were different for A. schnablii, P. genovensium, P. davisoni, and L. hesperia, due in part to projected distributions for these latter species in dry inter-Andean valleys according to the SDMs. Conclusions: The Tumbesian region represents a significant portion (40-96 %) of the predicted distribution of seven of the eight species studied, underscoring the importance of this region for bat conservation. Our results show likely distributions for these species and provide an important basis for identifying research gaps and developing conservation measures for threatened bats in the Tumbes biodiversity hotspot.
Assuntos
Animais , Quirópteros/classificação , Peru , Espécies em Perigo de Extinção , EquadorRESUMO
The impacts of grazing on rangelands have historically been studied within the framework of the equilibrium model, which predicts significant impacts of grazing on ecosystems. However, in recent decades, studies have observed a non-equilibrium pattern, suggesting that abiotic factors play a primary role compared to grazing. These studies are primarily focused on rangelands, despite animal husbandry occurring in other biomes, such as seasonally dry tropical forests. Our study examines the influence of goat grazing on biodiversity and forest succession in the Brazilian dry forest (Caatinga). Considering its high interannual precipitation variability, we hypothesize a response that aligns with the non-equilibrium paradigm. We established a gradient of grazing intensity and history in areas at different stages of vegetation succession. A survey of tree - shrub and herbaceous species was conducted at each site and the biomass of both strata was quantified. Linear mixed models and Permanova were employed to assess differences in richness, composition, structure, and biomass among the areas. Our results suggest that grazing (history and intensity) and forest fallow age did not affect species richness, but only species composition. Low and high grazing intensity drive ecosystems toward similar compositions, which align with the non-equilibrium model predictions. Biomass in the herbaceous layer remained unaffected by grazing history, intensity, or forest fallow age, whereas woody biomass was influenced by grazing intensity in older forest fallows. Although trees in low-intensity grazing sites were significantly taller compared to those in other levels, overall, grazing did not disrupt the natural succession process. Older forest fallows exhibited greater diversity and higher basal area compared to new forest fallows, irrespective of grazing intensity. Our findings suggest that: a) grazing has minimal effects on biodiversity and biomass due to non-equilibrium dynamics, and b) with appropriate management, grazing can coexist with the conservation of the Caatinga.
Assuntos
Biodiversidade , Florestas , Herbivoria , Brasil , Animais , Biomassa , Cabras , Monitoramento Ambiental , ÁrvoresRESUMO
Abstract Beaucarnea inermis is an endemic species from Northeast Mexico, in the states of San Luis Potosí and Tamaulipas. It is appreciated as an ornamental plant, so its populations are subject to the poaching of individuals for illegal trade. Previous studies determined that their populations have been affected due to the disturbance since the incidence of anthropogenic activities affects the viability of the species. Here we determine the current conservation status of B. inermis and identify their main risk factor by performing an extinction risk assessment based on the Annex II "Method for Evaluation of Risk of Extinction of Plants in Mexico". We studied 10 populations of B. inermis from protected and non-protected areas in San Luis Potosí and Tamaulipas. We considered the MER criteria: A) geographical distribution characteristics, B) habitat characteristics, C) intrinsic biological vulnerability, and D) impact of human activity. Using field and analyzed data, the MER assessment gives 1.91 points that confirm B. inermis is correctly classified as an Endangered species. The natural protected areas where the species occurs represent cores for its protection; however, the surface of these areas may not be sufficient without biological corridors that connect them.
Resumen Beaucarnea inermis es una especie endémica del Noroeste de México distribuida en los estados de San Luis Potosí y Tamaulipas. Es apreciada como planta ornamental, por lo que sus poblaciones están sujetas al saqueo de individuos para su comercialización ilegal. En trabajos anteriores se determinó que sus poblaciones han sido afectadas debido al disturbio por la incidencia de actividades antrópicas que afectan su viabilidad. En la presente contribución se determina el nivel de riesgo de B. inermis con base en el Anexo Normativo II "Método de Evaluación de Riesgo de Extinción de Plantas en México". Se estudiaron 10 poblaciones de B. inermis en San Luis Potosí y Tamaulipas, tanto en áreas naturales protegidas como en sitios no protegidos. Los criterios MER considerados fueron: A) características de la distribución geográfica, B) características del hábitat, C) vulnerabilidad biológica intrínseca y D) impacto de la actividad humana. El análisis MER arroja un valor de 1.91 que, confirma a B. inermis dentro de la categoría de Amenazada. Las áreas naturales protegidas donde se distribuye la especie funcionan como núcleos de protección, sin embargo, su superficie puede no ser suficiente sin la presencia de corredores biológicos que las conecten.
RESUMO
The Caatinga biome in Brazil comprises the largest and most continuous expanse of the seasonally dry tropical forest (SDTF) worldwide; nevertheless, it is among the most threatened and least studied, despite its ecological and biogeographical importance. The spatial distribution of volumetric wood stocks in the Caatinga and the relationship with environmental factors remain unknown. Therefore, this study intends to quantify and analyze the spatial distribution of wood volume as a function of environmental variables in Caatinga vegetation in Bahia State, Brazil. Volumetric estimates were obtained at the plot and fragment level. The multiple linear regression techniques were adopted, using environmental variables in the area as predictors. Spatial modeling was performed using the geostatistical kriging approach with the model residuals. The model developed presented a reasonable fit for the volume m3 ha with r2 of 0.54 and Root Mean Square Error (RMSE) of 10.9 m3 ha1. The kriging of ordinary residuals suggested low error estimates in unsampled locations and balance in the under and overestimates of the model. The regression kriging approach provided greater detailing of the global wood volume stock map, yielding volume estimates that ranged from 0.01 to 109 m3 ha1. Elevation, mean annual temperature, and precipitation of the driest month are strong environmental predictors for volume estimation. This information is necessary to development action plans for sustainable management and use of the Caatinga SDTF in Bahia State, Brazil.(AU)
Assuntos
Madeira/análise , Brasil , Modelos Lineares , Titulometria , Dispersão VegetalRESUMO
The present study analyses the geographical distribution, conservation status, and nomenclature of Peruvian endemic Pedersenia weberbaueri. The species distribution was modelled using MaxEnt based on occurrence data and bioclimatic variables. The conservation status of the species was assessed against the categories and criteria of the IUCN Red List, and nomenclatural and typification issues were resolved. The potential distribution map of P. weberbaueri shows that the species is restricted to the seasonally dry tropical forests of the Marañón valley within a narrow latitudinal, longitudinal, and elevational range. Consequently, we propose to categorise the species as Endangered (EN) and provide the necessary information for its inclusion in the IUCN Red List. Finally, we resolve nomenclatural issues and designate a lectotype. The results contribute to the biological knowledge of P. weberbaueri and support subsequent conservation management plans.
El presente estudio analiza la distribución geográfica, el estado de conservación y la nomenclatura de la endémica peruana Pedersenia weberbaueri. La distribución de especies se modeló usando MaxEnt con base en datos de ocurrencia y variables bioclimáticas. Se evaluó el estado de conservación de la especie frente a las categorías y criterios de la Lista Roja de la UICN y se resolvieron cuestiones de nomenclatura y tipificación. El mapa de distribución potencial de P. weberbaueri muestra que la especie está restringida a los bosques tropicales estacionalmente secos del valle del Marañón dentro de un estrecho rango latitudinal, longitudinal y altitudinal. En consecuencia, proponemos categorizar a la especie como En Peligro (EN) y brindar la información necesaria para su inclusión en la Lista Roja de la UICN. Finalmente, resolvemos cuestiones de nomenclatura y designamos un lectotipo. Los resultados contribuyen al conocimiento biológico de P. weberbaueri y respaldan los planes de manejo de conservación posteriores.
RESUMO
In dioecious, bee-pollinated tree species, male and female flowers offer different resources. It is unclear how this unbalanced quantity and quality of floral resources affects flower visits and pollen transfer to female flowers. We asked, what characteristics of flowering and dynamics of resource production by trees favour flights of bees between male and female trees. We quantified the floral resources produced by individual flowers and entire trees of Myracrodruon urundeuva (Anacardiaceae), measured pollen flow to female flowers, fruit set of naturally pollinated flowers and determined the effective pollinators. Crown volume of male trees was four-fold, flower number 15-fold and nectar volume 60 times higher than in female trees. While ~70% of male flowers opened in the morning, ~70% of female flowers opened in the afternoon. Fruit set was 27%. Stingless bee species were the main pollinators, while honeybees were common only on male flowers. Strongly unbalanced production of floral resources, high potential lifespan of female flowers and anticipated opening of male flowers favour pollinator movement and pollen deposition on female flowers, albeit low (0.003% of pollen that reached stigmas), but sufficient to produce thousands of fruits per tree. Besides being an astonishing pollen and nectar source for numerous social bee species, only a few of them were effective pollinators. Our quantitative approach to floral resource production of each gender provides new insights, such as the proportion of resources allocated to each gender and the corresponding behaviour of flower visitors, for understanding the reproductive strategy of dioecious tropical mass-flowering trees.
Assuntos
Polinização , Árvores , Animais , Abelhas , Flores , Néctar de Plantas , PólenRESUMO
Chronic anthropogenic disturbance (CAD) and climate change represent two of the major threats to biodiversity globally, but their combined effects are not well understood. Here we investigate the individual and interactive effects of increasing CAD and decreasing rainfall on the composition and taxonomic (TD), functional (FD) and phylogenetic diversity (PD) of plants possessing extrafloral nectaries (EFNs) in semi-arid Brazilian Caatinga. EFNs attract ants that protect plants against insect herbivore attack and are extremely prevalent in the Caatinga flora. EFN-bearing plants were censused along gradients of disturbance and rainfall in Catimbau National Park in north-eastern Brazil. We recorded a total of 2243 individuals belonging to 21 species. Taxonomic and functional composition varied along the rainfall gradient, but not along the disturbance gradient. There was a significant interaction between increasing disturbance and decreasing rainfall, with CAD leading to decreased TD, FD and PD in the most arid areas, and to increased TD, FD and PD in the wettest areas. We found a strong phylogenetic signal in the EFN traits we analysed, which explains the strong matching between patterns of FD and PD along the environmental gradients. The interactive effects of disturbance and rainfall revealed by our study indicate that the decreased rainfall forecast for Caatinga under climate change will increase the sensitivity of EFN-bearing plants to anthropogenic disturbance. This has important implications for the availability of a key food resource, which would likely have cascading effects on higher trophic levels.
Assuntos
Efeitos Antropogênicos , Formigas , Animais , Brasil , Humanos , Filogenia , Néctar de PlantasRESUMO
In seasonally dry tropical forests, plant functional type can be classified as deciduous low wood density, deciduous high wood density, or evergreen high wood density species. While deciduousness is often associated with drought-avoidance and low wood density is often associated with tissue water storage, the degree to which these functional types may correspond to diverging and unique water use strategies has not been extensively tested.We examined (a) tolerance to water stress, measured by predawn and mid-day leaf water potential; (b) water use efficiency, measured via foliar δ13C; and (c) access to soil water, measured via stem water δ18O.We found that deciduous low wood density species maintain high leaf water potential and low water use efficiency. Deciduous high wood density species have lower leaf water potential and variable water use efficiency. Both groups rely on shallow soil water. Evergreen high wood density species have low leaf water potential, higher water use efficiency, and access alternative water sources. These findings indicate that deciduous low wood density species are drought avoiders, with a specialized strategy for storing root and stem water. Deciduous high wood density species are moderately drought tolerant, and evergreen high wood density species are the most drought tolerant group.Synthesis. Our results broadly support the plant functional type framework as a way to understand water use strategies, but also highlight species-level differences.
RESUMO
Abstract Species lists available from floristic and phytosociological studies contain important information about species distributions that are useful for making biogeographical inferences and even to evaluate conservation status of species and ecosystems. In the case of the Caatinga, this information may contribute to challenging the pre-established idea that it is a homogeneous vegetation unit. The strong relation between the substrate and the plant assemblages of the Caatinga may characterise different types of vegetation. In this way, the objective of the present study is to evaluate whether differences in the distribution of Cactaceae relate to distinctive types of substrate (sedimentary and crystalline) as much in terms of floristic richness as species density. Concomitantly, we evaluated the conservation status of the Caatinga areas studied. To obtain the data, we undertook a bibliographic revision of floristic and phytosociological studies in the Caatinga and constructed a similarity matrix using the selected floristic studies in order to evaluate the relation among different areas of Caatinga. We found that 48 areas included Cactaceae species; 33 species distributed in 14 genera were recorded. Among these taxa, Cereus jamacaru was the species that presented the largest number of occurrences, appearing in 17 areas, followed by Pilosocereus gounellei (=Xiquexique gounellei), found in 11 studies, and Tacinga inamoena in 10. The grouping analysis resulted in the formation of 10 groups, with a remarkable relationship between species and soil type. There were differences in both the diversity and density of species related with the degree of conservation of the Caatinga, noticeable from the direct relationship between conservation and richness and, indirectly, between density and number of species.
Resumen Las listas de especies presentadas en trabajos florísticos o fitosociológicos proporcionan importante información sobre distribución, útil para realizar inferencias biogeográficas y evaluar el estado de conservación de especies o incluso de ecosistemas. En el caso de los bosques secos del nordeste de Brasil, conocidos como Caatinga, el análisis de esas listas puede contribuir para confrontar ideas previamente establecidas sobre la homogeneidad de esa unidad de vegetación. La fuerte relación entre el sustrato y los ensambles de plantas de la Caatinga pueden caracterizar distintos tipos de vegetación. Es así como, el objetivo de este trabajo es evaluar sí la distribución de Cactaceae está relacionada con los tipos de sustrato (sedimentar y cristalino), sea con la riqueza florística o la densidad de las especies. Al mismo tiempo, evaluamos el estado de conservación de las áreas estudiadas de la Caatinga. Los datos fueron obtenidos a partir de revisiones bibliográficas, de estudios de florística y fitosociología en la Caatinga. Para evaluar las distintas áreas, con los estudios florísticos seleccionados se preparó una matriz de similaridad. Se encontró que, 48 áreas tenían especies de Cactaceae; 33 especies distribuidas en 14 géneros fueron listadas. Cereus jamacaru fue la especie con el mayor número de puntos en 17 áreas, seguido por Pilosocereus gounellei (=Xiquexique gounellei), encontrado en 11 estudios y Tacinga inamoena, en 10. El análisis resultó en la formación de 10 grupos con fuertes relaciones entre especies y tipos de sustratos. También, encontramos diferencias en diversidad de especies en relación con el estado de conservación de la Caatinga, notable por las relaciones directas entre conservación y riqueza de especies, e indirectas entre densidad y número de especies.
RESUMO
Phylogenetic niche conservatism (PNC) shapes the distribution of organisms by constraining lineages to parti-cular climatic conditions. Conversely, if areas with similar climates are geographically isolated, diversificationmay also be limited by dispersal. Neotropical xeric habitats provide an ideal system to test the relative roles ofclimate and geography on diversification, as they occur in disjunct areas with similar biotas. Sicariinae sandspiders are intimately associated with these xeric environments, particularly seasonally dry tropical forests(SDTFs) and subtropical deserts/scrublands in Africa (Hexophthalma) and the Neotropics (Sicarius). We explorethe role of PNC, geography and biome shifts in their evolution and timing of diversification. We estimated atime-calibrated, total-evidence phylogeny of Sicariinae, and used published distribution records to estimateclimatic niche and biome occupancy. Topologies were used for estimating ancestral niches and biome shifts. Weused variation partitioning methods to test the relative importance of climate and spatially autocorrelatedfactors in explaining the spatial variation in phylogenetic structure ofSicariusacross the Neotropics. NeotropicalSicariusare ancient and split from their African sister-group around 90 (57–131) million years ago. Most spe-ciation events took place in the Miocene. Sicariinae records can be separated in two groups corresponding totemperate/dry and tropical/seasonally dry climates. The ancestral climatic niche of Sicariinae are temperate/dryareas, with 2–3 shifts to tropical/seasonally dry areas inSicarius. Similarly, ancestral biomes occupied by thegroup are temperate and dry (deserts, Mediterranean scrub, temperate grasslands), with 2–3 shifts to tropical,seasonally dry forests and grasslands. Most of the variation in phylogenetic structure is explained by long-distance dispersal limitation that is independent of the measured climatic conditions. Sicariinae have an ancientassociation to arid lands, suggesting that PNC prevented them from colonizing mesic habitats. However, nichesare labile at a smaller scale, with several shifts from deserts to SDTFs. This suggests that PNC and long-distancedispersal limitation played major roles in confining lineages to isolated areas of SDTF/desert over evolutionaryhistory, although shifts between xeric biomes occurred whenever geographical opportunities were presented