Sampath S. Seneviratne

Heuglin's Gulls (Larus heuglini) GPS‐tracked from Sri Lanka to the Arctic in successive years followed a combination of coastal and overland routes through Eurasia (~8000 km) instead of the shortest maritime (~15,000 km) or shortest transcontinental (6346 km) routes, revealing a novel transcontinental passage for seabirds between the Indian and Arctic Oceans.

Island ecosystems have emerged as vital model systems for evolutionary and speciation studies due to their unique environmental conditions and biodiversity. This study investigates the population divergence, hybridization dynamics, and evolutionary history of hybridizing golden‐backed and red‐backed Dinopium flameback woodpeckers on the island of Sri Lanka, providing insights into speciation processes within an island biogeographic context. Utilizing genomic analysis based on next‐generation sequencing, we revealed that the Dinopium hybrid zone on this island is a complex three‐way hybrid zone involving three genetically distinct populations: two cryptic populations of golden‐backed D. benghalense in the north and one island‐endemic red‐backed population of D. psarodes in the south of Sri Lanka. Our findings indicate asymmetric introgressive hybridization, where alleles from the southern D. psarodes introgress into the northern D. benghalense genome while phenotype remains adapted to their respective northern arid and southern wet habitats. The discovery of two genetically distinct but phenotypically similar D. benghalense populations in northern Sri Lanka highlights the process of cryptic population differentiation within island ecosystems. These populations trace their ancestry back to a common ancestor, similar to the Indian form D. b. tehminae, which colonized Sri Lanka from mainland India during the late Pleistocene. Subsequent divergence within the island, driven by selection, isolation by distance, and genetic drift, led to the current three populations. Our findings provide evidence of cryptic diversification and within‐island population divergence, highlighting the complexity of hybridization and speciation processes. These findings further emphasize the intricate nature of evolutionary dynamics in island ecosystems.

The variation in climatic conditions over space and time is considered a major driving force in speciation. Gloger's rule is one such rule that broadly explains the variation in the colouration of endotherms (birds and mammals) with the effects of climatic parameters. This predicts that endothermic animals tend to have darker colouration in warm and rainy climates. Here we have tried to explain the variation in the belly white colour in Dicrurus caerulescens (White-bellied Drongo), an overall black coloured bird with a variable white belly. The dark bellied birds are considered the subspecies D. c., and the pale bellied birds are considered D. c.insularis (in dryzone of Sri Lanka). A total number of 112 individuals of adult White-bellied Drongo, including field (n=23) and museum samples (n=36) from Sri Lanka (Total 59), and museum samples from India (n=45) and Nepal (n=8) which were deposited at the National Museum of Sri Lanka, Field Museum of Natural History, USA and the Natural History Museum, UK were taken into consideration. The length of the white belly was measured using a dial calliper adopting a standardized method to minimize inconsistencies. To understand how the extent of white belly varied with respect to precipitation and temperature, we adopted generalized least squares (GLS) methods accounting for spatial autocorrelation between data points. The climatic variables were extracted from the world climatic data through QGIS software. The GLS methods were carried out using the ―nlme‖ package in the R Software for different orders of Autoregressive-moving average (ARMA) for the squared value of white belly length. To find the best fitting model, we used the Akaike information criterion (AIC) using the package ―AICcmodavg‖ in the R. From this, we found a negative significant effect of the interaction between the temperature and precipitation for the white belly length over the studied area in ARMA (1, 1) correlation (-3.72e-01±-0.022, t= -2.23, pKeywords: Dicrurus caerulescens, Colouration, Gloger's rule, Temperature, Precipitation

The aptly named microcormorants (currently placed in the genus Microcarbo) form a morphologically diminutive and distinct clade sister to all other living cormorants and shags. However, the relationships within Microcarbo are largely speculative. Sequence data resolve these relationships unambiguously, with our phylogeny suggesting that the microcormorants separated from the other cormorants ~16 Mya and showing that the two African species [the reed (or long-tailed) cormorant, Microcarbo africanus, and the crowned cormorant, Microcarbo coronatus] are closely related sister taxa, forming a clade that diverged from the other microcormorants ~12 Mya. The deep split between the African microcormorants and the others is considerably older than many well-recognized generic splits within the cormorants (e.g. Leucocarbo and Phalacrocorax). Thus, we suggest that the African microcormorants warrant their own genus, and we erect Afrocarbo, with type species Pelecanus africanus. Within the reduced Microcarbo, we estimate that the little pied cormorant (Microcarbo melanoleucos of Australasia) separated from the sister pair of the Javanese and pygmy cormorants (respectively, Microcarbo niger from south/southeast Asia and Microcarbo pygmaeus from Europe) ~9 Mya and that the latter two species split ~2 Mya. Given the age of these splits, the microcormorants appear to represent another example of morphological conservatism in the Suliformes.

The Kentish Plover Charadrius alexandrinus Linnaeus 1758 is a common shorebird in Eurasia and North Africa that breeds in a variety of habitats, exhibits different extents of migratory behaviour and is an emerging model species of breeding system evolution. Here we focus on the resident population found across the southern tip of India and Sri Lanka, and re‐evaluate its systematic status based on phenotypic and genetic distinctiveness from a sympatric migrant, Charadrius alexandrinus sensu stricto, and the recently elevated closely related Charadrius dealbatus in East Asia. We show that the Sri Lankan and South Indian (South Asian) population differs in body size, moulting pattern and plumage coloration from C. alexandrinus and C. dealbatus. Furthermore, based on two mitochondrial, two sex‐linked and 11 autosomal microsatellite markers from 378 individuals, we show that these three taxa have moderate genetic differentiation (F_st 0.078–0.096). The South Asian taxon is sister to the clade of C. alexandrinus sensu stricto and C. dealbatus with an estimated divergence time of 1.19 million years ago. We also examined ornithological records of major museum collections in Asia, Europe and North America for the south Asian taxon to evaluate its biogeographical and taxonomic status. Based on differences in genotype, phenotype, allochronic migratory pattern and breeding range, we resurrect the most suitable synonym, Charadrius alexandrinus seebohmi Hartert and Jackson, 1915, and elevate the nomen to the species level with the proposed English name ‘Hanuman Plover’.

Isolating barriers that drive speciation are commonly studied in the context of two‐species hybrid zones. There is, however, evidence that more complex introgressive relationships are common in nature. Here, we use field observations and genomic analysis, including the sequencing and assembly of a novel reference genome, to study an emergent hybrid zone involving two colliding hybrid zones of three woodpecker species: red‐breasted, red‐naped, and yellow‐bellied sapsuckers (Sphyrapicus ruber, S. nuchalis, and S. varius). Surveys of the area surrounding Prince George, British Columbia, Canada, show that all three species are sympatric, and Genotyping‐by‐Sequencing identifies hybrids from each species pair and birds with ancestry from all three species. Observations of phenotypes and genotypes of mated pairs provide evidence for assortative mating, though there is some heterospecific pairing. Hybridization is more extensive in this tri‐species hybrid zone than in two di‐species hybrid zones. However, there is no evidence of a hybrid swarm and admixture is constrained to contact zones, so we classify this region as a tension zone and invoke selection against hybrids as a likely mechanism maintaining species boundaries. Analysis of sapsucker age classes does not show disadvantages in hybrid survival to adulthood, so we speculate the selection upholding the tension zone may involve hybrid fecundity. Gene flow among all sapsuckers in di‐species hybrid zones suggests introgression probably occurred before the formation of this tri‐species hybrid zone, and might result from bridge hybridization, vagrancies, or other three‐species interactions.