Aim Kingfishers are the most species‐rich family in the avian order, Coraciiformes. Their modern distribution is largely pantropical; however, global species diversity is unevenly distributed. For example, 19 of the 114 kingfisher species occur in New Guinea, whereas only six species occur in the entire New World. This disparity in diversity suggests regions with high species richness could represent the ancestral range of the family. Furthermore, some clades of kingfishers (Ceyx, Todiramphus) are thought to be the product of rapid insular radiations. Here, we investigated the biogeographical history and speciation dynamics of the Alcedinidae using a fully sampled molecular phylogeny. Location Global. Taxon Kingfishers (Aves: Coraciiformes: Alcedinidae). Methods We inferred a time‐calibrated, species‐level phylogeny of kingfishers from DNA sequences. Our data set comprised up to five Sanger‐sequenced gene regions for all species (one mitochondrial, one nuclear exon and three nuclear introns), plus genus‐level sampling of thousands of ultraconserved elements. We estimated ancestral ranges of kingfishers and explored macroevolutionary rate shifts and diversification rates across the phylogeny. Results We recovered a well‐supported phylogeny of kingfishers that includes 34 species whose phylogenetic relationships were not previously known. The pygmy‐kingfishers (subfamily Alcedininae) sit on a long branch, sister to all other kingfishers: subfamilies Cerylinae and Halcyoninae. Crown‐group kingfishers originated in the Indomalayan region approximately 27 Ma with subsequent colonizations into Africa (six times), the New World (twice) and Australasia (representing several major radiations). Main conclusions Oceanic islands of Wallacea, the Philippines and Oceania promoted multiple, independent radiations in three species‐rich genera: Ceyx, Actenoides and Todiramphus. In particular, Todiramphus showed patterns consistent with explosive and recent diversification relative to the background speciation rate of non‐Todiramphus kingfishers, which we attribute to recent colonization of the vast archipelagos of Wallacea and the Pacific.

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The evolution of pantropically distributed clades has puzzled palaeo-and neontologists for decades regarding the different hypotheses about where they originated. In this study, we explored how a pantropical distribution arose in a diverse clade with a rich fossil history: the avian order Coraciiformes. This group has played a central role in the debate of the biogeographical history of Neoaves. However, the order lacked a coherent species tree to inform study of its evolutionary dynamics. Here, we present the first complete species tree of Coraciiformes, produced with 4858 ultraconserved elements, which supports two clades: (1) Old World-restricted bee-eaters, rollers and ground-rollers; and (2) New World todies and motmots, and cosmopolitan kingfishers. Our results indicated two pulses of diversification: (1) major lineages of Coraciiformes arose in Laurasia approximately 57 Ma, followed by independent dispersals into equatorial regions, possibly due to tracking tropical habitat into the lower latitudes-the Coracii (Coraciidae + Brachypteraciidae) into the Afrotropics, bee-eaters throughout the Old World tropics, and kingfishers into the Australasian tropics; and (2) diversification of genera in the tropics during the Miocene and Pliocene. Our study supports the important role of Laurasia as the geographical origin of a major pantropical lineage and provides a new framework for comparative analyses in this charismatic bird radiation.

The complex island archipelagoes of Wallacea and Melanesia have provided empirical data behind integral theories in evolutionary biology, including allopatric speciation and island biogeography. Yet, questions regarding the relative impact of the layered biogeographic barriers, such as deep-water trenches and isolated island systems, on faunal diversification remain underexplored. One such barrier is Wallace’s Line, a significant biogeographic boundary that largely separates Australian and Asian biodiversity. To assess the relative roles of biogeographic barriers—specifically isolated island systems and Wallace’s Line—we investigated the tempo and mode of diversification in a diverse avian radiation, Corvides (Crows and Jays, Birds-of-paradise, Vangas, and allies). We combined a genus-level dataset of thousands of ultraconserved elements (UCEs) and a species-level, 12-gene Sanger sequence matrix to produce a well-resolved supermatrix tree that we leveraged to explore the group’s historical biogeography and effects of biogeographic barriers on their macroevolutionary dynamics. The tree is well-resolved and differs substantially from what has been used extensively for past comparative analyses within this group. We confirmed that Corvides, and its major constituent clades, arose in Australia and that a burst of dispersals west across Wallace’s Line occurred after the uplift of Wallacea during the mid-Miocene. We found that dispersal across this biogeographic barrier were generally rare, though westward dispersals were two times more frequent than eastward dispersals. Wallacea’s central position between Sundaland and Sahul no doubt acted as a bridge for island-hopping dispersal out of Australia, across Wallace’s Line, to colonize the rest of Earth. In addition, we found that the complex island archipelagoes east of Wallace’s Line harbor the highest rates of net diversification and are a substantial source of colonists to continental systems on both sides of this biogeographic barrier. Our results support emerging evidence that island systems, particularly the geologically complex archipelagoes of the Indo-pacific, are drivers of species diversification.

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Niche expansion is a critical step in the speciation process. Large brains linked to improved cognitive ability may enable species to expand their niches and forage in new ways, thereby promoting speciation. Despite considerable work on ecological divergence in brain size and its importance in speciation, relatively little is known about how brain shape relates to behavioral, ecological, and taxonomic diversity at macroevolutionary scales. This is due, in part, to inherent challenges with quantifying brain shape across many species.Here, we present a novel, semiautomated approach for rapidly phenotyping brain shape using semilandmarks derived from X-ray computed micro-tomography (microCT) scans.We then test its utility by parsing evolutionary trends within a diverse radiation of birds, kingfishers (Aves: Alcedinidae). Multivariate comparative analyses reveal that rates of brain shape evolution, but not beak shape, are positively correlated with lineage diversification rates. Distinct brain shapes are further associated with changes in body size and foraging behavior, suggesting both allometric and ecological constraints on brain shape evolution. These results are in line with the idea of brains acting as a "master regulator" of critical processes governing speciation, such as dispersal, foraging behavior, and dietary niche.

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Avian malaria and related haemosporidian parasites (genera Haemoproteus, Plasmodium, and Leucocytozoon) affect bird demography, species range limits, and community structure, yet they remain unsurveyed in most bird communities and populations. We conducted a community-level survey of these vector-transmitted parasites in New Mexico, USA, to describe their diversity, abundance, and host associations. We focused on the breeding-bird community in the transition zone between piñon-juniper woodland and ponderosa pine forests (elevational range: 2,150–2,460 m). We screened 186 birds representing 49 species using both standard PCR and microscopy techniques to detect infections of all three avian haemosporidian genera. We detected infections in 68 out of 186 birds (36.6%), the highest proportion of which were infected with Haemoproteus (20.9%), followed by Leucocytozoon (13.4%), then Plasmodium (8.0%). We sequenced mtDNA for 77 infections representing 43 haplotypes (25 Haemoproteus, 12 Leucocytozoon, 6 Plasmodium). When compared to all previously known haplotypes in the MalAvi and GenBank databases, 63% (27) of the haplotypes we recovered were novel. We found evidence for host specificity at the avian clade and species level, but this specificity was variable among parasite genera, in that Haemoproteus and Leucocytozoon were each restricted to three avian groups (out of six), while Plasmodium occurred in all groups except non-passerines. We found striking variation in infection rate among host species, with nearly universal infection among vireos and no infection among nuthatches. Using rarefaction and extrapolation, we estimated the total avian haemosporidian diversity to be 70 haplotypes (95% CI [43–98]); thus, we may have already sampled ∼60% of the diversity of avian haemosporidians in New Mexico pine forests. It is possible that future studies will find higher diversity in microhabitats or host species that are under-sampled or unsampled in the present study. Fortunately, this study is fully extendable via voucher specimens, frozen tissues, blood smears, parasite images, and documentation provided in open-access databases (MalAvi, GenBank, and ARCTOS).