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Following behavior is a well-documented foraging specialization in Neotropical birds, which consists of individuals of solitary or mixed-flocking species following other moving animals to capture fleeing prey. Here, we report two observations of the cryptic forest-falcon, Micrastur mintoni following troops of primates during an ornithological inventory in the eastern Brazilian Amazon. During both observations, the falcon emitted a typical vocalization and captured fleeing insects dispersed by the primates moving through the forest while foraging. This is the first report of an apparently commensal association between a Micrastur forest falcon and two species of primates.

Host phylogenetic relatedness and ecological similarity are thought to contribute to parasite community assembly and infection rates. However, recent landscape level anthropogenic changes may disrupt host-parasite systems by impacting functional and phylogenetic diversity of host communities. We examined whether changes in host functional and phylogenetic diversity, forest cover, and minimum temperature influence the prevalence, diversity, and distributions of avian haemosporidian parasites (genera Haemoproteus and Plasmodium) across 18 avian communities in the Atlantic Forest. To explore spatial patterns in avian haemosporidian prevalence and taxonomic and phylogenetic diversity, we surveyed 2241 individuals belonging to 233 avian species across a deforestation gradient. Mean prevalence and parasite diversity varied considerably across avian communities and parasites responded differently to host attributes and anthropogenic changes. Avian malaria prevalence (termed herein as an infection caused by Plasmodium parasites) was higher in deforested sites, and both Plasmodium prevalence and taxonomic diversity were negatively related to host functional diversity. Increased diversity of avian hosts increased local taxonomic diversity of Plasmodium lineages but decreased phylogenetic diversity of this parasite genus. Temperature and host phylogenetic diversity did not influence prevalence and diversity of haemosporidian parasites. Variation in the diversity of avian host traits that promote parasite encounter and vector exposure (host functional diversity) partially explained the variation in avian malaria prevalence and diversity. Recent anthropogenic landscape transformation (reduced proportion of native forest cover) had a major influence on avian malaria occurrence across the Atlantic Forest. This suggests that, for Plasmodium, host phylogenetic diversity was not a biotic filter to parasite transmission as prevalence was largely explained by host ecological attributes and recent anthropogenic factors. Our results demonstrate that, similar to human malaria and other vector-transmitted pathogens, prevalence of avian malaria parasites will likely increase with deforestation.

Made available in DSpace on 2022-04-28T19:42:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 The family Thamnophilidae is a species-rich Neotropical radiation of passerine birds. Current classification of its 235 species is mostly based on morphological similarities, but recent studies integrating comprehensive phenotypic and phylogenetic data have redefined taxonomic limits of several taxa. Here, we assess generic relationships of Herpsilochmus, Sakesphorus, Thamnophilus, Biatas, and Dysithamnus using DNA sequences from the mitochondrion, nuclear exons, and ultraconserved elements, with further attention to interspecific relationships within Herpsilochmus. We show that Herpsilochmus and Sakesphorus are not monophyletic. We resolve Herpsilochmus sellowi as a deep-branch sister to the monotypic genus Biatas and Sakesphorus cristatus as sister to a clade comprising Herpsilochmus sensu stricto and Dysithamnus. These results are consistent across loci, obtained via concatenation and coalescent-based analyses, and supported by likelihood-ratio tests of the distribution of our sampled coalescent histories. The phenotypic distinctiveness of both H. sellowi and Biatas argues against merging them into a single genus. Because no generic name is available for H. sellowi, we describe a monotypic genus. The polyphyly of Sakesphorus warrants recognition of the available generic name Sakesphoroides for the distinctive and monotypic S. cristatus. Furthermore, we recover 6 well-supported species groups within Herpsilochmus sensu stricto. Within the context of the family as a whole, the ubiquity of long terminal branches representing monotypic genera points to extinction events among ancestors of these lineages. We suggest that retention of ancestral characters or random genetic drift coupled with extensive extinction could explain the high degree of morphological and ecological similarity across these taxa, but we highlight the potential role of the environment in driving adaptive phenotypic convergence. Finally, our results send a cautionary message against the blind use of phylogenies containing imputed data based on taxonomy due to the increasingly frequent mismatches between traditional taxonomic classification and molecular phylogenies. LAY SUMMARY We conduct phylogenomic analyses to infer generic relationships of Herpsilochmus, Sakesphorus, Thamnophilus, Biatas, and Dysithamnus. Using thousands of ultraconserved elements, exons, and mitochondrial DNA, we consistently show that the genus Herpsilochmus is not monophyletic because H. sellowi is a sister of the monotypic species Biatas nigropectus. Because the phenotypic distinctiveness of H. sellowi and B. nigropectus argues against merging them into a single genus and there is no available generic name for H. sellowi, we describe a monotypic genus for this species. We also found polyphyly of the genus Sakesphorus, warranting recognition of the available generic name Sakesphoroides for Sakesphorus cristatus. Our results provide a robust framework for downstream analyses of biogeographic and phenotypic evolution of Herpsilochmus antwrens and allies. This study adds to the increasing body of literature documenting the mismatch between traditional avian taxonomic classifications based on external morphology and evolutionary histories traced by modern genetic tools. Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology Harvard University Seção de Aves Museu de Zoologia Universidade de São Paulo Museum of Natural Science and Department of Biological Sciences Louisiana State University Departamento de Zoologia Universidade Federal do Paraná Centro Politécnico Programa de Pós-Graduação em Zoologia Departamento de Zoologia Universidade Federal do Paraná Centro Politécnico Departamento de Ciências Biológicas e Ambientais Instituto de Biociências Universidade Estadual Paulista Mater Natura - Instituto de Estudos Ambientais Gund Institute for Environment The University of Vermont Rubenstein School of Environment and Natural Resources The University of Vermont Departamento de Zoologia Universidade Federal de Pernambuco Coordenação de Zoologia Museu Paraense Emílio Goeldi Finnish Museum of Natural History University of Helsinki Department of Ecology and Evolutionary Biology University of Tennessee Departamento de Ciências Biológicas e Ambientais Instituto de Biociências Universidade Estadual Paulista

Calcium, the most versatile second messenger, regulates essential biology including crucial cellular events in embryogenesis. We investigated impacts of calcium channels and purinoceptors on neuronal differentiation of normal mouse embryonic stem cells (ESCs), with outcomes being compared to those of in vitro models of Huntington’s disease (HD). Intracellular calcium oscillations tracked via real-time fluorescence and luminescence microscopy revealed a significant correlation between calcium transient activity and rhythmic proneuronal transcription factor expression in ESCs stably expressing ASCL-1 or neurogenin-2 promoters fused to luciferase reporter genes. We uncovered that pharmacological manipulation of L-type voltage-gated calcium channels (VGCCs) and purinoceptors induced a two-step process of neuronal differentiation. Specifically, L-type calcium channel-mediated augmentation of spike-like calcium oscillations first promoted stable expression of ASCL-1 in differentiating ESCs, which following P2Y2 purinoceptor activation matured into GABAergic neurons. By contrast, there was neither spike-like calcium oscillations nor responsive P2Y2 receptors in HD-modeling stem cells in vitro. The data shed new light on mechanisms underlying neurogenesis of inhibitory neurons. Moreover, our approach may be tailored to identify pathogenic triggers of other developmental neurological disorders for devising targeted therapies.

The environment can impose constraints on signal transmission properties such that signals should evolve in predictable directions (Sensory Drive Hypothesis). However, behavioral and ecological factors can limit investment in more than one sensory modality leading to a trade-off in use of different signals (Transfer Hypothesis). In birds, there is mixed evidence for both sensory drive and transfer hypothesis. Few studies have tested sensory drive while also evaluating the transfer hypothesis, limiting understanding of the relative roles of these processes in signal evolution. Here, we assessed both hypotheses using acoustic and visual signals in male and female antwrens (Thamnophilidae), a species-rich group that inhabits diverse environments and exhibits behaviors, such as mixed-species flocking, that could limit investment in different signal modalities. We uncovered significant effects of habitat (sensory drive) and mixed-species flocking behavior on both sensory modalities, and we revealed evolutionary trade-offs between song and plumage complexity, consistent with the transfer hypothesis. We also showed sex- and trait-specific responses in visual signals that suggest both natural and social selection play an important role in the evolution of sexual dimorphism. Altogether, these results support the idea that environmental (sensory drive) and behavioral pressures (social selection) shape signal evolution in antwrens.

BackgroundNovel developmental functions have been attributed to the P2X7 receptor (P2X7R) including proliferation stimulation and neural differentiation. Mouse embryonic stem cells (ESC), induced with retinoic acid to neural differentiation, closely assemble processes occurring during neuroectodermal development of the early embryo.Principal findingsP2X7R expression together with the pluripotency marker Oct-4 was highest in undifferentiated ESC. In undifferentiated cells, the P2X7R agonist Bz-ATP accelerated cell cycle entry, which was blocked by the specific P2X7R inhibitor KN-62. ESC induced to neural differentiation with retinoic acid, reduced Oct-4 and P2X7R expression. P2X7R receptor-promoted intracellular calcium fluxes were obtained at lower Bz-ATP ligand concentrations in undifferentiated and in neural-differentiated cells compared to other studies. The presence of KN-62 led to increased number of cells expressing SSEA-1, Dcx and β3-tubulin, as well as the number of SSEA-1 and β3-tubulin-double-positive cells confirming that onset of neuroectodermal differentiation and neuronal fate determination depends on suppression of P2X7R activity. Moreover, an increase in the number of Ki-67 positive cells in conditions of P2X7R inhibition indicates rescue of progenitors into the cell cycle, augmenting the number of neuroblasts and consequently neurogenesis.ConclusionsIn embryonic cells, P2X7R expression and activity is upregulated, maintaining proliferation, while upon induction to neural differentiation P2X7 receptor expression and activity needs to be suppressed.