Niche filling slows the diversification of Himalayan songbirds.

Speciation generally involves a three-step process--range expansion, range fragmentation and the development of reproductive isolation between spatially separated populations. Speciation relies on cycling through these three steps and each may limit the rate at which new species form. We estimate phylogenetic relationships among all Himalayan songbirds to ask whether the development of reproductive isolation and ecological competition, both factors that limit range expansions, set an ultimate limit on speciation. Based on a phylogeny for all 358 species distributed along the eastern elevational gradient, here we show that body size and shape differences evolved early in the radiation, with the elevational band occupied by a species evolving later. These results are consistent with competition for niche space limiting species accumulation. Even the elevation dimension seems to be approaching ecological saturation, because the closest relatives both inside the assemblage and elsewhere in the Himalayas are on average separated by more than five million years, which is longer than it generally takes for reproductive isolation to be completed; also, elevational distributions are well explained by resource availability, notably the abundance of arthropods, and not by differences in diversification rates in different elevational zones. Our results imply that speciation rate is ultimately set by niche filling (that is, ecological competition for resources), rather than by the rate of acquisition of reproductive isolation.

Discovery of a relict lineage and monotypic family of passerine birds.

Analysis of one of the most comprehensive datasets to date of the largest passerine bird clade, Passerida, identified 10 primary well-supported lineages corresponding to Sylvioidea, Muscicapoidea, Certhioidea, Passeroidea, the 'bombycillids' (here proposed to be recognized as Bombycilloidea), Paridae/Remizidae (proposed to be recognized as Paroidea), Stenostiridae, Hyliotidae, Regulidae (proposed to be recognized as Reguloidea) and spotted wren-babbler Spelaeornis formosus. The latter was found on a single branch in a strongly supported clade with Muscicapoidea, Certhioidea and Bombycilloidea, although the relationships among these were unresolved. We conclude that the spotted wren-babbler represents a relict basal lineage within Passerida with no close extant relatives, and we support the already used name Elachura formosa and propose the new family name Elachuridae for this single species.

Avian Haemosporidian (Plasmodium and Haemoproteus) Status in Two Bird Groups (Old-World Flycatchers and Thrushes) of India and Their Phylogenetic Relationships with Other Lineages of the World.

PURPOSE: Avian haemosporidian may affect the host from body damage to the extinction of a population. Knowledge of their status may help in future avifauna conservation plans. Hence, their status in two bird groups of India and their phylogenetic relationships with other known lineages of the world were examined. METHODS: Cytochrome b gene sequences (479 bp) generated from India and available at MalAvi database were used to study the avian haemosporidian prevalence and phylogenetic analysis of lineages at local and world levels. RESULTS: One common (COLL2) and only once in the study (CYOPOL01, CHD01, CYORUB01, EUMTHA01, GEOCIT01) haemosporidian lineages were discovered. 5.88% prevalence of haemosporidian infection was found in 102 samples belonging to 6 host species. Haemoproteus prevalence was 4.90% across five host species (Phylloscopus trochiloides, Cyornis poliogenys, C. hainanus dialilaemus, C. rubeculoides, Eumiyas thalassinus) and Plasmodium prevalence was 0.98% in Geokichla citrina. Spatial phylogeny at the global level showed that COLL2 lineage, found in C. poliogenys in India, was genetically identical to H. pallidus lineages (COLL2) in parts of Africa, Europe, North America, Malaysia, and the Philippines. The Plasmodium lineage (GEOCIT01) was related to PADOM16 in Egypt, but the sequences were only 93.89% alike. CONCLUSIONS: Four new lineages of Haemoproteus and one of Plasmodium were reported. COLL2 similarity with other H. pallidus lineages may suggest their hosts as possible infection sources.

Determinants of northerly range limits along the Himalayan bird diversity gradient.

The primary explanation for the latitudinal gradient in species diversity must lie in why species fail to expand ranges across different climatic regimes. Theories of species gradients based in niche conservatism assume that whole clades are confined to particular climatic regimes because the traits they share limit adaptation to alternative regimes. We assess these theories in an analysis of the twofold decline in bird species richness along the Himalayas from the southeast to the northwest. The presence of fewer species in the northwest is entirely due to a steep decline in the number of forest species; species occupying more open habitats show a reversed gradient. Forest species numbers are exceptionally high at midelevations (1,000-2,000 m) in the southeast, which experience a warm, wet climate not present in the northwest, and a high proportion of these species fail to expand their range to the northwest. Despite this, many species do have populations or close relatives that straddle different climatic regimes along altitudinal gradients and/or the regional gradient, implying that climate-based niche conservatism per se does not strongly constrain range limits. We argue that climate- and competition-mediated resource distributions are important in setting northerly range limits and show that one measure of forest resources (foliage density) is lower in the northwest.

Rapid molecular assays for species and sex identification of swamp deer and other coexisting cervids in human-dominated landscapes of the Terai region and upper Gangetic plains, northern India: implications in understanding species distribution and population parameters.

Burgeoning pressures of habitat loss is a major cause of herbivore decline across India, forcing them to coexist with humans in non-protected areas. Their conservation in such landscapes is challenging due to paucity of ecological and demographic information. The northern subspecies of swamp deer, Rucervus duvaucelii duvaucelii, is one such herbivore that lives across human dominated landscapes in Terai region and upper Gangetic plains of north India. Here, we describe species-specific molecular markers and a cervid-specific molecular sexing assay for swamp deer and four other coexisting cervids sambar, chital, barking deer and hog deer. Our markers show species-specific band patterns and a high success rate of 88.21% in large number of field collected referencesamples for all species. Faecal pellets from pilot swamp deer survey samples from upper Ganges basin show 93.81% success rate, and only 5.5% misidentification based on morphological characteristics. Our cervid-specific molecular sexing multiplex assay accurately ascertained 81.15% samples to respective sexes. These molecular approaches provide an easy, quick and cheap option to generate critical information on herbivore population parameters and aid their conservation in this mosaic of protected and non-protected grassland habitats.

Regional influences on community structure across the tropical-temperate divide.

Many models to explain the differences in the flora and fauna of tropical and temperate regions assume that whole clades are restricted to the tropics. We develop methods to assess the extent to which biotas are geographically discrete, and find that transition zones between regions occupied by tropical-associated or temperate-associated biotas are often narrow, suggesting a role for freezing temperatures in partitioning global biotas. Across the steepest tropical-temperate gradient in the world, that of the Himalaya, bird communities below and above the freezing line are largely populated by different tropical and temperate biotas with links to India and Southeast Asia, or to China respectively. The importance of the freezing line is retained when clades rather than species are considered, reflecting confinement of different clades to one or another climate zone. The reality of the sharp tropical-temperate boundary adds credence to the argument that exceptional species richness in the tropics reflects species accumulation over time, with limited transgressions of species and clades into the temperate.