Speciation in Indo-Pacific swiftlets (Aves: Apodidae): integrating molecular and phenotypic data for a new provisional taxonomy of the Collocalia esculenta complex.

White-bellied swiftlets of the Collocalia esculenta complex constitute a radiation of colony-breeding swifts distributed throughout the tropical Indo-Pacific region. Resolution of their taxonomy is challenging due to their morphological uniformity. To analyze the evolutionary history of this complex, we combine new biometric measurements and results from plumage assessment of museum specimens with novel as well as previously published molecular data. Together, this body of information constitutes the largest systematic dataset for white-bellied swiftlets yet compiled, drawn from 809 individuals belonging to 32 taxa for which new molecular, biometric, and/or plumage data are presented. We propose changing the classification of white-bellied swiftlets, for which two species are currently recognized, to elevate eight regional forms to species level, and we also describe two new subspecies. The ten taxa we recommend recognizing at the species level are: Collocalia linchi (Java to Lombok, Sumatran hills), C. dodgei (montane Borneo), C. natalis (Christmas Island), C. affinis (Greater Sundas, including the Thai-Malay Peninsula and Andaman-Nicobar Islands), C. marginata (Philippines), C. isonota (Philippines), C. sumbawae (west Lesser Sundas), C. neglecta (east Lesser Sundas), C. esculenta (Sulawesi, Moluccas, New Guinea, Bismarck Archipelago, Solomon Islands), and C. uropygialis (Vanuatu, New Caledonia). Future molecular and morphological work is needed to resolve questions of speciation and population affinities in the Philippines, Christmas Island, Wallacea and central Melanesia, and to shed light on historic diversification and patterns of gene flow in the complex.

Bioacoustic and multi-locus DNA data of Ninox owls support high incidence of extinction and recolonisation on small, low-lying islands across Wallacea.

Known for their rich biodiversity and high level of endemism, the islands of Wallacea serve as natural laboratories for the study of spatio-temporal evolution and patterns of species diversification. Our study focuses on the owl genus Ninox, particularly the Southern Boobook (N. novaeseelandiae) and Moluccan Boobook (N. squamipila) complexes, which are widely distributed across Australasia. We conducted bioacoustic and multi-locus DNA analyses of 24 Ninox owl taxa to evaluate relationships and levels of divergence within the two complexes and ultimately assess the relationship between patterns of taxonomic differentiation and bioclimatic factors. We found that taxa that are vocally and/or genetically distinct from populations on the Australian mainland are found on islands that are significantly larger and higher in altitude than taxa that are vocally and/or genetically indistinct from populations on the Australian mainland. This pattern suggests that taxa occurring on small, low-lying Wallacean islands are likely to be recent colonisers that have dispersed from Australia. Overall, our observations demonstrate that the genus Ninox is likely to have colonised the Wallacean region multiple times as small, low-lying islands undergo frequent extinction, whereas populations on large and high-altitude islands are more resilient.

Micro-Computed Tomographic Evaluation of the Influence of Root Canal System Landmarks on Access Outline Forms and Canal Curvatures in Mandibular Molars.

INTRODUCTION: This study investigated the influence of anatomic root canal system landmarks on access outline forms of mandibular molars and correlated these to the theoretical distance of orifice relocation and changes in canal primary curvature. METHODS: Thirty relatively calcified human mandibular molars were selected and examined by micro-computed tomographic imaging. Three-dimensional volume reconstructions were made, root canal system landmarks identified, and plotted: canal orifices, canal position at the furcation level, and pulp horn location. Each landmark was separately projected onto the occlusal surface, and 3 access designs were respectively proposed: (1) minimally invasive, (2) straight-line furcation, and (3) straight-line radicular. For each access design, the theoretical distance of orifice relocation and canal primary curvature were determined. Data were submitted to 2-way repeated measures analysis of variance (α < 0.05). RESULTS: The orifice relocation distance required to obtain each type of access outline was greater for radicular-based accesses (0.97 ± 0.32 mm) than for furcation accesses (0.52 ± 0.30 mm, P < .001) and resulted in a greater change in canal primary curvature (P < .001; 15.9° ± 4.6° and 9.4° ± 4.3°, respectively). The canal primary curvature for each access outline type was statistically different from each other (P < .0001), whereas the minimally invasive access showed the highest mean angle (40.1° ± 8.4°) followed by the straight-line furcation (30.7° ± 7.5°) and the straight-line radicular accesses (24.2° ± 8.4°). CONCLUSIONS: The use of different landmarks to establish access outline designs affected the primary angle of curvature in relatively calcified mandibular molars.