Integrative taxonomy of Flatbill Flycatchers (Tyrannidae) reveals a new species from the Amazonian lowlands

Integrative taxonomic studies continue to reveal that many current polytypic species of birds are in fact constituted by two or more species and therefore have been central in uncovering ‘hidden’ or ‘cryptic’ biodiversity. The Olivaceous Flatbill (Aves: Tyrannidae: Rhynchocyclus olivaceus) currently has nine recognized subspecies distributed throughout the Neotropics, but so far, no complete phylogenetic hypothesis exists to test the validity and evolutionary relationships among them. To remedy this, we conducted a multi-character integrative taxonomic revision of the genus Rhynchocyclus, focusing on the polytypic R. olivaceus. The combination of a taxonomically dense sampled multilocus phylogeny (including three mitochondrial and two nuclear genes) with phenotypic analyses including morphological and vocal characters pointed to several taxonomic inconsistencies within R. olivaceus. The analyses strongly support that R. olivaceus is paraphyletic, with an exclusively cis-Andean clade (where the topotypic R. olivaceus is found) clustering as sister to Rhynchocyclus fulvipectus, to the exclusion of a clade grouping trans-Andean and western Amazonian populations currently placed in R. olivaceus—one of which is unnamed and fully diagnosable based on vocal and genetic characters. Consistent with the phylogenetic results, our vocal analyses identified at least four morphologically cryptic lineages within R. olivaceus that can be mutually diagnosed from each other by different loudsongs and call parameters. Therefore, we provide evidence for splitting these four groups into separate species, two of which are sympatric but not syntopic in western Amazonia, including an unnamed species described herein—Rhynchocyclus cryptus, sp. nov. urn:lsid:zoobank.org:act:2DC17190-2BDD-49EC-88E6-4CF2FC2562A3.     

Host community similarity and geography shape the diversity and distribution of haemosporidian parasites in Amazonian birds

Identifying the mechanisms driving the distribution and diversity of parasitic organisms and characterizing the structure of parasite assemblages are critical to understanding host–parasite evolution, community dynamics, and disease transmission risk. Haemosporidian parasites of the genera Plasmodium and Haemoproteus are a diverse and cosmopolitan group of bird pathogens. Despite their global distribution, the ecological and historical factors shaping the diversity and distribution of these protozoan parasites across avian communities and geographic regions remain unclear. Here we used a region of the mitochondrial cytochrome b gene to characterize the diversity, biogeographical patterns, and phylogenetic relationships of Plasmodium and Haemoproteus infecting Amazonian birds. Specifically, we asked whether, and how, host community similarity and geography (latitude and area of endemism) structure parasite assemblages across 15 avian communities in the Amazon Basin. We identified 265 lineages of haemosporidians recovered from 2661 sampled birds from 330 species. Infection prevalence varied widely among host species, avian communities, areas of endemism, and latitude. Composition analysis demonstrated that both malarial parasites and host communities differed across areas of endemism and as a function of latitude. Thus, areas with similar avian community composition were similar in their parasite communities. Our analyses, within a regional biogeographic context, imply that host switching is the main event promoting diversification in malarial parasites. Although dispersal of haemosporidian parasites was constrained across six areas of endemism, these pathogens are not dispersal‐limited among communities within the same area of endemism. Our findings indicate that the distribution of malarial parasites in Amazonian birds is largely dependent on local ecological conditions and host evolutionary relationships.     

Impact of Renal Sympathetic Denervation on Left Ventricular Structure and Function at 1-Year Follow-Up

Background

Catheter-based sympathetic renal denervation (RDN) is a recent therapeutic option for patients with resistant hypertension. However, the impact of RDN in left ventricular (LV) mass and function is not completely established. Our aim was to evaluate the effects of RDN on LV structure and function (systolic and diastolic) in patients with resistant hypertension (HTN).

Methods and Results

From a single centre prospective registry including 65 consecutive patients with resistant HTN submitted to RDN between July-2011 and April-2015, 31 patients with baseline and 1-year follow-up echocardiogram were included in this analysis. Mean age was 65±7 years, 48% were males, 71% had type 2 diabetes. Most had hypertension lasting for more than 10 years (90%), and were being treated with a median number of 6 anti-hypertensive drugs, including 74% on spironolactone. At 1-year, there was a significant decrease both on office SBP (176±24 to 149±13mmHg, p<0.001) and DBP (90±14 to 79±11mmHg, p<0.001), and also in 24h ABPM SBP (150±20 to 132±14mmhg, p<0.001) and DBP (83±10 to 74±9mmHg, p<0.001). There was also a significant decrease in LV mass from 152±32 to 136±34g/m² (p<0.001), an increase in LV end diastolic volume (93±18 to 111±27 mL, p = 0.004), an increase in LV ejection fraction (65±9 to 68±9%, p = 0.001) and mitral valve E deceleration time (225±49 to 247±51ms, p = 0.015) at 1-year follow up. There were no significant changes in left atrium volume index or in the distribution of patients among the different left ventricle geometric patterns and diastolic function subgroups.

Conclusions

In this single centre registry of patients with resistant hypertension, renal denervation was associated with significant reduction in both office and ABPM blood pressure and a significant decrease in left ventricle mass evaluated by transthoracic echocardiogram at 1 year follow-up.     

Current and historical factors drive variation of reproductive traits in unisexual mosses in Europe: A case study

Unisexual bryophytes provide excellent models to study the mechanisms that regulate the frequency of sexual versusasexual reproduction in plants, and their ecological and evolutionary implications. Here, we determined sex expression, phenotypic sex ratio, and individual shoot traits in 242 populations of the cosmopolitan moss Pseudoscleropodium purum spanning its whole distributional range. We tested whether niche differentiation, sex-specific differences in shoot size, and biogeographical history explained the spatial variation of reproductive traits. We observed high levels of sex expression and predominantly female-biased populations, although both traits showed high intraspecific variation among populations. Sex expression and sex ratio were partly explained by current macroscale environmental variation, with male shoots being less frequent at the higher end of the environmental gradients defined by the current distribution of the species. Female bias in population sex ratio was significantly lower in areas recolonized after the last glacial maximum (recent populations) than in glacial refugia (long-term persistent populations). We demonstrated that reproductive trait variation in perennial unisexual mosses is partially driven by macroscale and historical environmental variation. Based on our results, we hypothesize that sexual dimorphism in environmental tolerance and vegetative growth contribute to sex ratio bias over time, constraining the chances of sexual reproduction, especially in long-term persistent populations. Further studies combining genetic analyses and population monitoring should improve our understanding of the implications of the intraspecific variation in the frequency of sexual versusasexual reproduction in bryophyte population fitness and eco-evolutionary dynamics.     

Postzygotic isolation drives genomic speciation between highly cryptic Hypocnemis antbirds from Amazonia

How species evolve reproductive isolation in the species-rich Amazon basin is poorly understood in vertebrates. Here, we sequenced a reference genome and used a genome-wide sample of SNPs to analyze a hybrid zone between two highly cryptic species of Hypocnemis warbling-antbirds—the Rondonia warbling-antbird (H. ochrogyna) and Spix's warbling-antbird (H. striata)—in a headwater region of southern Amazonia. We found that both species commonly hybridize, producing F₁s and a variety of backcrosses with each species but we detected only one F₂-like hybrid. Patterns of heterozygosity, hybrid index, and interchromosomal linkage disequilibrium in hybrid populations closely match expectations under strong postzygotic isolation. Hybrid zone width (15.4 km) was much narrower than expected (211 km) indicating strong selection against hybrids. A remarkably high degree of concordance in cline centers and widths across loci, and a lack of reduced interspecific F_st between populations close to versus far from the contact zone, suggest that genetic incompatibilities have rendered most of the genome immune to introgression. These results support intrinsic postzygotic isolation as a driver of speciation in a moderately young cryptic species pair from the Amazon and suggest that species richness of the Amazon may be grossly underestimated.     

Combining phylogeography and landscape genetics of Xenopipo atronitens (Aves: Pipridae), a white sand campina specialist,to understand Pleistocene landscape evolution in Amazonia

Open vegetation (campinas and campinaranas) associated with white sand patches occurs in the form of islands in a forested matrix throughout the Amazon basin. Bird species restricted to these habitats have patchy distributions, although connectivity may have been influenced by past glacial cycles as a result of the substitution of forest by savanna. Because these landscape changes are a matter of debate in the history of Amazonia, we studied the diversification of Xenopipo atronitens, a white sand specialist, aiming to infer the effects of past climate changes. The split of Xenopipo atronitens from its sister species, Xenopipo uniformis, may be related to Tepuis erosion and retreat of escarpments during the Miocene, or to a dispersal event. Compared with birds from terra firme forest, X. atronitens has low genetic structure. Low levels of unidirectional gene flow were found from the Guyana Shield to adjacent areas. Demographic expansion starting approximately 25 kyr BP was detected for some populations and is probably related to the Last Glacial Maximum and subsequent climate improvement. Landscape genetic analyses indicate that the forested (terra firme) matrix acts as a barrier for the dispersal of X. atronitens. The results of the present study indicate that glacial cycles have deeply influenced Amazonian biogeographical history, demonstrating a complex interaction between forest and nonforest habitats during the Pleistocene. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 60–76.     

Molecular systematics of the Amazonian endemic genus Hylexetastes (Aves: Dendrocolaptidae): taxonomic and conservation implications

Hylexetastes woodcreepers are endemic to the terra firme forests of the Amazon basin. Currently, most taxonomic sources recognize two species of Hylexetastes (H. perrotii and H. stresemanni), each divided into three subspecies. Some authors maintain that the H. perrotii subspecies should be elevated to full species status. In particular, Hylexetastes perrotii brigidai is endemic to the eastern Amazon, the second Amazonian area of endemism (Xingu) most affected by deforestation and habitat degradation. Consequently, the taxonomic status of H. p. brigidai is of particular concern for conservation. Thus far, only morphological characters have been evaluated for the taxonomic delimitation of species and subspecies of Hylexetastes. We present a molecular phylogenetic analysis of all subspecies to help delimit Hylexetastes interspecific limits. Fragments of two mitochondrial (Cytb and ND2) and three nuclear genes (FGB5, G3PDH and MUSK) from 57 Hylexetastes specimens were sequenced. An ecological niche model was estimated to describe more accurately the potential distributions of taxa and to evaluate their vulnerability to ongoing deforestation. Phylogenetic analyses support the paraphyly of the polytypic H. perrotii as currently delimited and the elevation of Hylexetastes perrotii uniformis to full species rank, as well as the presence of three evolutionary significant units (ESUs) within this newly delimited species, including one grouping all H. p. brigidai specimens. Alternatively, under lineage-based species concepts, our results support at least five evolutionary species in Hylexetastes: H. stresemanni, H. undulatus, H. perrotii, H. uniformis and H. brigidai. Each of these taxa and ESUs are distributed in different interfluvial areas of the Amazon basin, which have different degrees of disturbance. Because they occupy the most heavily impacted region among all Hylexetastes ESUs, regular assessments of the conservation statuses of H. p. brigidai and both H. uniformis ESUs are paramount.