Biology subjects

da Silva, F. R.

Publications and source records attributed to da Silva, F. R..

4 recordsLinked to original sources

bioRxiv2022

Non-equilibrium processes prevail in shaping species richness and functional diversity of terrestrial vertebrates in a global hotspot

AimThe effects of equilibrium and nonequilibrium processes are generally investigated using species richness on a single biological group. However, little is known about how these two classes of processes also affect trait diversity, considering multiple taxa within the same geographical template. Here, we evaluated which variables representing equilibrium (topography, climate, and primary productivity) and nonequilibrium (diversification rate and evolutionary time) processes best explain species richness and trait diversity of four clades of vertebrates within the same global hotspot. We also investigated how trait disparity has accumulated over time and whether there are congruent spatial patterns between groups. LocationAtlantic Rainforest Time periodContemporary. Major taxa studiedTerrestrial vertebrates. MethodsWe tested whether the spatial pattern of Functional Dispersion (FDis), richness, diversification rate, and evolutionary time of each group are correlated. We used a spatially explicit structural equation model to test how species richness and functional dispersion are influenced by variables representing equilibrium and nonequilibrium mechanisms. Additionally, we explored how trait disparity accumulated over time in the four groups. ResultsWe found that non-equilibrium proxies, evolutionary time and diversification rate, played a primary role in driving species richness and trait diversity, with elevation and climate variables having only an indirect effect species and trait diversity via diversification rate and evolutionary time. We found a congruent pattern of species richness among all groups, except among ectotherms. In contrast, the spatial distribution of evolutionary time was distinct for each group. Main conclusionsDespite nonequilibrium processes were more important for generating large-scale diversity patterns within the same geographical template, the interplay between evolutionary time and dispersal ability have disparately determined the assembly of communities.

ecology↗

bioRxiv2021

Global and regional ecological boundaries drive abrupt changes in avian frugivory interactions

Species interactions can propagate disturbances across space, though ecological and biogeographic boundaries may limit this spread. We tested whether large-scale ecological boundaries (ecoregions and biomes) and human disturbance gradients increase dissimilarity among ecological networks, while accounting for background spatial and elevational effects and differences in network sampling. We assessed network dissimilarity patterns over a broad spatial scale, using 196 quantitative avian frugivory networks (encompassing 1,496 plant and 1,003 bird species) distributed across 67 ecoregions and 11 biomes. Dissimilarity in species and interactions, but not in network structure, increased significantly across ecoregion and biome boundaries and along human disturbance gradients. Our findings suggest that ecological boundaries contribute to maintaining the worlds biodiversity of interactions and mitigating the propagation of disturbances at large spatial scales. One-Sentence SummaryEcoregions and biomes delineate the large-scale distribution of plant-frugivore interactions.

ecology↗

bioRxiv2019

Seed-dispersal networks lose complexity in tropical forest fragments

Seed dispersal interactions involve key ecological processes in tropical forests that help to maintain ecosystem functioning. Yet this functionality may be threatened by increasing habitat loss, defaunation and fragmentation. However, generalist species, and their interactions, can benefit from the habitat change caused by human disturbance while more specialized interactions mostly disappear. Therefore changes in the structure of the local, within fragment, networks can be expected. Here we investigated how the structure of seed-dispersal networks changes along a gradient of increasing habitat fragmentation. We analysed 16 bird seed-dispersal assemblages from forest fragments of a biodiversity-rich ecosystem. We found significant species-, interaction- and network-area relationships, yet the later was determined by the number of species remaining in each community. The number of frugivorous bird and plant species, their interactions, and the number of links per species decreases as area is lost in the fragmented landscape. In contrast, network nestedness has a negative relationship with fragment area, suggesting an increasing generalization of the network structure in the gradient of fragmentation. Network specialization was not significantly affected by area, indicating that some network properties may be invariant to disturbance. Still, the local extinction of partner species, paralleled by a loss of interactions and specialist-specialist bird-plant seed dispersal associations suggests the functional homogenization of the system as area is lost. Our study provides empirical evidence for network-area relationships driven by the presence/absence of remnant species and the interactions they perform.\n\nRESUMOInteracoes de dispersao de sementes formam um processo ecologico chave em florestas tropicais onde colaboram na manutencao do funcionamento do ecossistema. Porem, esta funcionalidade pode estar ameacada pelo aumento na perda e fragmentacao do habitat. Enquanto especies generalistas e suas interacoes podem se beneficiar da mudanca de habitat causada por disturbios antropicos, interacoes envolvendo especies mais especialistas sao, na maioria, eliminadas. Desta forma, mudancas nas redes locais, dentro de fragmentos florestais, sao esperadas. Neste trabalho nos investigamos como a estrutura de redes de dispersao de sementes mudam em um gradiente de fragmentacao do habitat. Nos analisamos 16 comunidades de dispersao de sementes espacialmente explicitas e distribuidas em fragmentos florestais de um ecossistema rico em biodiversidade. Nos encontramos relacoes significativas entre a area do fragmento e especies, interacoes e estrutura das redes, sendo que o ultimo foi determinado pelo numero de especies remanescentes em cada comunidade. O numero de especies de aves frugivoras e plantas e as interacoes entre eles, bem como o numero de links por especie diminuiram significativamente conforme a area dos fragmentos e perdida. Por outro lado, o aninhamento da rede mostrou uma relacao negativa com a area do fragmento, sugerindo um aumento da generalizacao da estrutura das redes com a fragmentacao do habitat. No entanto, o grau de especializacao das redes nao foi afetado pela area, indicando que algumas propriedades de rede podem ser resistentes a perturbacao. Sendo assim, a extincao local de especies parceiras, conjuntamente com a perda das interacoes e associacoes planta-dispersor mais especializadas, sugere uma homogeneizacao do sistema conforme a area do fragmento e perdida. Nosso estudo fornece evidencias empiricas para as relacoes rede-area, sendo estas direcionadas pela presenca e/ou ausencia das especies remanescentes bem como das interacoes que estas realizam.

ecology↗

bioRxiv2018

Generation Of iPSC-Derived Human Peripheral Sensory Neurons Releasing Substance P Elicited By TRPV1 Agonists

Neural crest stem cells (NCPCs) have been shown to differentiate into various cell types and tissues during embryonic development, including sensory neurons. The few studies addressing the generation of NCPCs and peripheral sensory neurons (PSNs) from human induced Pluripotent Stem Cells (hiPSCs), generated sensory cells without displaying robust activity. Here, we describe an efficient strategy for hiPSCs differentiation into NCPCs and functional PSNs using chemically defined media and factors to achieve efficient differentiation, confirmed by the expression of specific markers. After 10 days hiPSCs differentiated into NCPCs, cells were then maintained in neural induction medium containing defined growth factors for PSNs differentiation, followed by 10 days in neonatal human epidermal keratinocytes-(HEKn-) conditioned medium. We observed a further increase in PSN markers expression and neurites length after conditioned medium treatment. The resulting neurons released substance P (SP) in response to nociceptive agents such as anandamide and resiniferatoxin. Anandamide induced substance P release via activation of TRPV1 and not CB1. Transcriptomic analysis of the PSNs revealed the main dorsal root ganglia (DRG) neuronal markers and a transcriptional profile compatible with C-LTMR. TRPV1 was detected by immunofluorescence and RNA-Seq in multiple experiments. In conclusion, the developed strategy generated PSNs useful for drug screening that could be applied to patient-derived hiPSCs, consisting in a powerful tool to model human diseases in vitro.

neuroscience↗