A Case Study in Amazonian Biogeography: Vocal and DNA -Sequence Variation in Hemitriccus Flycatchers.

Ongoing debate about the evolutionary history of the Amazonian avifauna suffers from a shortage of data. Especially needed are thorough geographic sampling, sensitive markers of genetic diversity, and historical data in the form of explicit phylogenies. I examined patterns of geographic variation in three widespread species complexes of nearly identical Amazonian flycatchers in the genus Hemitriccus, based on spectrographic analysis of vocalizations and phylogenetic analysis of DNA sequences (1026 base pairs of cytochrome b from 44 individuals) from throughout Amazonia. Although members of the three complexes are extremely difficult to distinguish morphologically and have long been confused by taxonomists, they represent three well-defined clades separated by a remarkable 10% sequence divergence. Within clades, vocally defined populations correspond closely to genetic units and more accurately than does current taxonomy. Area cladograms of the three species complexes are not strictly concordant and show five-fold differences in inter-regional sequence divergences, suggesting either different rates of evolution or different ages of vicariance events. Two taxa, the H. zosterops and H. inornatus complexes, show similar, but not identical, patterns of a basal north-south split along the current path of the Amazon River and a more recent east-west split within the northern population, consistent with the possibility of a single set of vicariance events affecting both taxa similarly and simultaneously. Nevertheless, within-population genetic variability differs dramatically between the two groups, suggesting unique histories or life-history traits. The third complex, H. minor , shows a different geographic pattern of distribution and genetic divergence. Presently, no single hypothesis proposed to explain patterns of Amazonian biogeography adequately or uniquely accounts for the patterns found in this study. A null hypothesis is proposed, in which current environmental conditions are sufficient to explain existing patterns without invoking particular historical changes. Based on the results of this study, the null hypothesis cannot be rejected. More such studies on many more taxa will be necessary before evolutionary patterns are sufficiently well described to differentially implicate specific historical processes

Onde está o símbolo da ornitologia brasileira? a distribuição geográfica da ararajuba (guarouba guarouba - psittacidae)

The Golden Parakeet (Guarouba guarouba) is a poorly known, endangered psittacid endemic to the Brazilian Amazon. We examined point records of the species to identify possible temporal changes in its occurrence and to model its potential distribution. It is known from roughly 70 localities. After 1987, new records extend the known distribution considerably to the southwest, whereas regions at the eastern end of the range do not contain recent records. We interpret the former as improved knowledge of the true historical distribution based on increased sampling, and the latter as a genuine range retraction, best explained by deforestation in that region. We estimate the species' current area of occurrence at 340,000 km2, embracing less than 65% of its original range. Distribution models predict a potential distribution of the Golden Parakeet throughout a region of relatively low humidity, at the interface between lowland and submontane rainforest at the border of the Brazilian Shield. This distribution coincides with the colonization frontier ("arc of deforestation") in the Amazon, which places the species' future in serious risk. Existing and planned parks and reserves in the Tapajos River region appear to offer the best hope for protection of currently known populations. Furthermore, we hope that our distribution model leads to intensive searches and discovery of populations previously unknown and to improved understanding of habitat preference and niche

Response of understory avifauna to annual flooding of Amazonian floodplain forests

The annual flooding in the Amazon basin transforms the understory of floodplain forests into an aquatic environment. However, a great number of non-aquatic bird species occupy the understory and midstory of these forests. In general, these birds are thought to be sedentary and territorial, but the way they adapt to this dramatic seasonal transformation has never been described in detail. In this study, we describe avifaunal strategies to cope with seasonal flooding in the lower Purus region, central Amazonia, Brazil. We conducted focal observations of five insectivorous species occupying the lowest forest strata in two types of floodplain forest (black- and whitewater) during the low- and high-water seasons. For each observation, the height of the bird above the substrate (ground or water), its vertical position in the forest, and vegetation density around the bird were noted. All species remained present in the floodplain forests during the two seasons and were not recorded in adjacent unflooded (terra firme) forest. In general, birds migrated vertically to higher forest strata and most species (three of the five) occupied similar vegetation densities independent of water level. Despite the tendency of all species to rise in relative vertical position at high water, there was a reduction in height above substrate for four of the five species, suggesting that their position relative to water was not an important microhabitat element for them. Responses were similar in the two floodplain forest types. It is likely that the decrease in available space during the flood, combined with similar vertical displacement in arthropods, leads to increased prey density for understory insectivorous birds and permits year-round territoriality without major habitat shifts

Avian ecological succession in the Amazon: A long-term case study following experimental deforestation

Approximately 20% of the Brazilian Amazon has now been deforested, and the Amazon is currently experiencing the highest rates of deforestation in a decade, leading to large-scale land-use changes. Roads have consistently been implicated as drivers of ongoing Amazon deforestation and may act as corridors to facilitate species invasions. Long-term data, however, are necessary to determine how ecological succession alters avian communities following deforestation and whether established roads lead to a constant influx of new species. We used data across nearly 40 years from a large-scale deforestation experiment in the central Amazon to examine the avian colonization process in a spatial and temporal framework, considering the role that roads may play in facilitating colonization. Since 1979, 139 species that are not part of the original forest avifauna have been recorded, including more secondary forest species than expected based on the regional species pool. Among the 35 species considered to have colonized and become established, a disproportionate number were secondary forest birds (63%), almost all of which first appeared during the 1980s. These new residents comprise about 13% of the current community of permanent residents. Widespread generalists associated with secondary forest colonized quickly following deforestation, with few new species added after the first decade, despite a stable road connection. Few species associated with riverine forest or specialized habitats colonized, despite road connection to their preferred source habitat. Colonizing species remained restricted to anthropogenic habitats and did not infiltrate old-growth forests nor displace forest birds. Deforestation and expansion of road networks into terra firme rainforest will continue to create degraded anthropogenic habitat. Even so, the initial pulse of colonization by nonprimary forest bird species was not the beginning of a protracted series of invasions in this study, and the process appears to be reversible by forest succession. © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd

Twenty years later: An update to the birds of the biological dynamics of forest fragments project, Amazonas, Brazil

Although species lists from throughout Amazonia have become available, relatively complete inventories based on longterm work remain rare. Longitudinal comparisons at well-studied sites provide the best opportunities for describing communities and identifying changes in regional avifaunas. Within central Amazonia, no region has received as much consistent ornithological coverage as the terra firme forests north of Manaus, Brazil, at the Biological Dynamics of Forest Fragments Project (BDFFP). Here we provide an updated list of the area, including notes on all species added between 1997 and 2017. We recorded 21 species new for the site, most of which (>75%) are birds that prefer várzea or second-growth forest. This brings the cumulative BDFFP list up to 409 species, the majority (66%) of which inhabit primary terra firme forest. Together, this confirms that the regional terra firme community had been well-characterized by the 1990s, and that species additions to the list over the last 20 years are consistent with a changing landscape as urbanization, agriculture, and second-growth spread from Manaus. The final product continues to represent the most complete avian inventory for a single site in all of lowland Amazonia. © 2017, Sociedade Brasileira de Ornitologia. All rights reserved

The avifauna of the Brazilian state of Roraima: Bird distribution and biogeography in the Rio Branco basin

The Brazilian state of Roraima represents a meaningful biogeographical unit, enclosing the entire basin of the Rio Branco, a major river in the Amazon basin. Roraima is also an area of high habitat diversity where terra fi rme forest, seasonally fl ooded forest, white-sand forest, savanna, gallery and dry forest, and the vegetation associated with the tepuis, all occur within a relatively small area (225,000km2) by Amazonian standards. We provide the fi rst comprehensive compilation of the avifauna of the state in forty years. We integrated the results of our own fi eld work, where we recorded 512 bird species, with data gathered from museum specimens and from published sources. We present a list of 741 bird species for the state of Roraima, 38 of which are mentioned for the fi rst time for the state. We also provide a list of 15 species previously cited for Roraima that we consider hypothetical, and predict the presence of another 69 species that we consider likely to be recorded in the state with further fi eld work. We also present details on some of our most interesting records, which include the fi rst Brazilian specimen of Atalotriccus pilaris, and the second locality for Brazil of Myrmeciza disjuncta. We conclude that habitat heterogeneity (beta-diversity) is responsible for 60% of the avian diversity of Roraima, whereas regional endemism (gamma-diversity) accounts for about one third of the bird species occurring exclusively in terra fi rme forests. We analyze the biogeographical patterns of avian distributions within the state, in relation to the different habitats present in Roraima, and discuss some of the main conservation problems in the state of Roraima, driven by the expansion of monocultures such as soybean, acacia, and rice plantations which are putting at risk large expanses of savannas, wetlands, dry and gallery forests

Major range extension for Orange-fronted Plushcrown Metopothrix aurantiaca in the central Amazon of Brazil

Orange-fronted Plushcrown Metopothrix aurantiaca is a unique, but easily overlooked, small furnariid found in the midstorey and canopy of riverine areas in the Amazon. The species' previously published distribution includes parts of southernmost Colombia, eastern Ecuador, eastern Peru, northern Bolivia and western Brazil. In the easternmost part of its distribution (Brazil), M. aurantiaca occurs in the states of Acre, Amazonas and Rondônia, east to 64°W. We present nine new records of the species in Brazil, all of them east of its previously known distribution and together extending the range by c.750 km. These new records derive from sampling that includes collecting expeditions, exhaustive várzea surveys, and incidental observations. We propose a new continuous distribution for this species restricted to white-water river floodplains with known occurrences. © 2019 The Authors

Revisão da distribuição do vite-vite-de-cabeça-cinza Hylophilus pectoralis (Passeriformes: Vireonidae), com notificação de sua ocorrência no Triângulo Mineiro e noroeste de São Paulo

The Ashy-headed Greenlet has a spotty distribution over a broad area in Amazonia, both north and south of the Solimões-Amazonas river. It is mostly found second-growth, forest edge and water-edge habitats, including mangroves and gallery and varzea forests. The species also occurs in the Pantanal, the Chiquitano Forests, and in the Cerrado of central and northeastern Brazil, including the Brazilian states of Goiás, Maranhão and Piauí. This paper presents new records extending its distribution to the south, including southwest Minas Gerais (the "Triângulo Mineiro" region), southern Goiás, northwest São Paulo and eastern Mato Grosso do Sul, suggesting a recent colonization of those regions parallel to the one shown by the closely related H. thoracicus in southeastern Brazil

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