Secondary contact before the completion of reproductive isolation can alter speciation trajectories by impeding divergence through gene flow or accelerating it via reinforcement. Using genomic data, we investigated secondary contact between two pairs of Copsychus (Muscicapidae) lineages in Borneo: subspecies of magpie‐robins ( C. saularis ) and two species of shamas ( C. malabaricus and C. stricklandii ). Although eastern and...

Intraspecific polymorphism in birds, especially plumage colour polymorphism, and the mechanisms that control it are an area of active research in evolutionary biology. The black‐headed bulbul ( Brachypodius atriceps ) is a polymorphic species with two distinct morphs, yellow and grey. This species inhabits the mainland and virtually all continental islands of Southeast Asia where yellow morphs predominate, but on two islands i...

Aim Physiological tolerances and biotic interactions along habitat gradients are thought to influence species occurrence. Distributional differences caused by such forces are particularly noticeable on tropical mountains, where high species turnover along elevational gradients occurs over relatively short distances and elevational distributions of particular species can shift among mountains. Such shifts are interpreted as evi...

Aim The traditional view of species’ distributions is that they are less abundant near the edges of their ranges and more abundant towards the centre. Testing this pattern is difficult because of the complexity of distributions across wide geographical areas. An alternative strategy, however, is to measure species’ distributional patterns along elevational gradients. We applied this strategy to examine whether lowland forest b...

Aim A current model of rain forest population diversification in Sundaland specifies east–west vicariance into refugia during the early Pleistocene. In some taxa, this division was followed by dispersal and apparent secondary contact on Borneo in the late Pleistocene. To investigate genetic, morphological, spatial and temporal characteristics of the model, we compared genomic population and plumage variation among four bird sp...

Aim Our understanding of population diversification in the lowlands of Sundaland has improved substantially over the last 20 years through phylogeographical study, but we know almost nothing about population diversification in the mountains of the region. Here, we apply genomic analysis and habitat modelling to the phylogeography of Chlorocharis emiliae , the Mountain Black‐eye, an endemic montane bird of Borneo with a sky‐isl...

Sundaland has a dynamic geographic history because its landmasses were periodically interconnected when sea levels fell during glacial periods. Superimposed on this geographic dynamism were environmental changes related to climatic oscillations. To investigate how tropical taxa responded to such changes, we studied the divergence and demographic history of two co‐distributed rainforest passerine species, Arachnothera longirost...

Aim Magpie‐robins and shamas are forest and woodland birds of south Asia. There are two genera: Trichixos for the monotypic T. pyrrhopygus , and Copsychus for other species. Two species are widespread, whereas the others are restricted to specific islands. Endemicity is highest in the Philippines. Using phylogenetic methods, we examined how this group came to its unusual distribution. Location Mainland Asia from India to south...

Aim The oriental magpie‐robin ( Copsychus saularis ) of South and Southeast Asia is a phenotypically variable species that appears to be closely related to two endemic species of the western Indian Ocean: the Madagascar magpie‐robin ( Copsychus albospecularis ) and the Seychelles magpie‐robin ( Copsychus sechellarum ). This unusual distribution led us to examine evolutionary relationships in magpie‐robins, and also the taxonom...