ORCID Profile
0000-0003-1014-182X
Current Organisations
National University of Singapore
,
University of Tasmania
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Publisher: Oxford University Press (OUP)
Date: 09-2022
Abstract: Quantifying the magnitude of the global extinction crisis is important but remains challenging, as many extinction events pass unnoticed owing to our limited taxonomic knowledge of the world’s organisms. The increasing rarity of many taxa renders comprehensive s ling difficult, further compounding the problem. Vertebrate lineages such as birds, which are thought to be taxonomically well understood, are therefore used as indicator groups for mapping and quantifying global extinction. To test whether extinction patterns are adequately gauged in well-studied groups, we implemented ancient-DNA protocols and retrieved whole genomes from the historic DNA of museum specimens in a widely known songbird radiation of shamas (genus Copsychus) that is assumed to be of least conservation concern. We uncovered cryptic ersity and an unexpected degree of hidden extinction and terminal endangerment. Our analyses reveal that & % of the phylogenetic ersity of this radiation is already either extinct in the wild or nearly so, including the two genomically most distinct members of this group (omissus and nigricauda), which have so far flown under the conservation radar as they have previously been considered subspecies. Comparing the genomes of modern s les with those from roughly a century ago, we also found a significant decrease in genetic ersity and a concomitant increase in homozygosity affecting various taxa, including small-island endemics that are extinct in the wild as well as subspecies that remain widespread across the continental scale. Our application of modern genomic approaches demonstrates elevated levels of allelic and taxonomic ersity loss in a songbird clade that has not been listed as globally threatened, highlighting the importance of ongoing reassessments of extinction incidence even across well-studied animal groups. Key words: extinction, introgression, white-rumped shama, conservation.
Publisher: Wiley
Date: 05-03-2020
DOI: 10.1111/EVA.12918
Publisher: Oxford University Press (OUP)
Date: 22-02-2016
DOI: 10.1111/BIJ.12768
Publisher: Springer Science and Business Media LLC
Date: 05-09-2023
Publisher: Cambridge University Press (CUP)
Date: 16-11-2021
DOI: 10.1017/S095927092000060X
Abstract: The Straw-headed Bulbul Pycnonotus zeylanicus is one of South-East Asia’s most threatened songbirds due to relentless demand for the regional cage-bird trade. The species was recently uplisted from ‘Endangered’ to ‘Critically Endangered’ only two years after its previous uplisting. Intriguingly, populations in highly urbanised Singapore appear relatively secure. However, the last Singaporean density estimates, derived from traditional census methods, were obtained nearly two decades ago in 2001. A recent population estimate in 2016 was derived from the census work in 2001 coupled with relative abundance indices from population trends. We thus performed systematic field surveys using the distance s ling method, estimating 573 ± 185 in iduals nation-wide, with a break-down of 217 ± 81 on the main island of Singapore and 356 ± 104 birds on the satellite of Pulau Ubin. Taken together, the total population estimate reported here comprises 22.9–57.3% of the global wild population, underscoring the importance of Singapore as a stronghold for the species. In spite of its apparently secure status in Singapore, the species remains susceptible to local and foreign trapping pressures. Based on our assessment, we propose a number of local and regional conservation measures to ensure the continued survival of populations in Singapore.
Publisher: Wiley
Date: 18-05-2020
DOI: 10.1111/IBI.12839
Publisher: Springer Science and Business Media LLC
Date: 23-10-2018
DOI: 10.1038/S41598-018-34101-7
Abstract: Leaf warblers (Aves Phylloscopidae) are a erse clade of insectivorous, canopy-dwelling songbirds widespread across the Old World. The taxonomy of Australasian leaf warblers is particularly complex, with multiple species-level ergences between island taxa in the region requiring further scrutiny. We use a combination of morphology, bioacoustics, and analysis of thousands of genome-wide markers to investigate and describe a new species of Phylloscopus leaf warbler from the island of Rote in the Lesser Sundas, Indonesia. We show that this new Rote Leaf Warbler is morphologically and genomically highly distinct from its congenerics, but do not find vocal differentiation between different island taxa. We discuss the behaviour and ecology of this highly distinctive new species, and make recommendations about its conservation status. We believe this constitutes the first description of a novel bird species that is partly based on insights from massive amounts of genome-wide DNA markers.
Publisher: Springer Science and Business Media LLC
Date: 23-09-2020
DOI: 10.1038/S41598-020-72428-2
Abstract: In today’s environmental crisis, conservationists are increasingly confronted with terminally endangered species whose last few surviving populations may be affected by allelic introgression from closely related species. Yet there is a worrying lack of evidence-based recommendations and solutions for this emerging problem. We analyzed genome-wide DNA markers and plumage variability in a critically endangered insular songbird, the Black-winged Myna (BWM, Acridotheres melanopterus ). This species is highly threatened by the illegal wildlife trade, with its wild population numbering in the low hundreds, and its continued survival urgently depending on ex-situ breeding. Its three subspecies occur along a geographic gradient of melanism and are variably interpreted as three species. However, our integrative approach revealed that melanism poorly reflects the pattern of limited genomic differentiation across BWM subspecies. We also uncovered allelic introgression into the most melanistic subspecies, tertius , from the all-black congeneric Javan Myna ( A. javanicus ), which is native to the same islands. Based on our results, we recommend the establishment of three separate breeding programs to maintain subspecific traits that may confer local adaptation, but with the option of occasional cross-breeding between insurance populations in order to boost genetic ersity and increase overall viability prospects of each breeding program. Our results underscore the importance of evidence-based integrative approaches when determining appropriate conservation units. Given the rapid increase of terminally endangered organisms in need of ex-situ conservation, this study provides an important blueprint for similar programs dealing with phenotypically variable species.
Publisher: Elsevier BV
Date: 28-10-2020
DOI: 10.1186/S40657-020-00227-4
Abstract: The Elegant Pitta ( Pitta elegans ) complex displays a remarkable ersity of morphological and bioacoustic traits across five taxa currently recognized as subspecies. They differ in plumage characteristics (such as red versus black belly patches supercilium color and extent and white versus black throats), in lifestyle (resident versus migratory) and in vocalizations. We investigated the morphological, bioacoustic and ecological differences across all taxa after recent studies demostrated the importance of these traits in recognizing biological species limits across pittas. Morphometric analysis was carried out by measuring tarsus, wing, tail and bill lengths of 15 specimens at the Natural History Museum, UK, and plumages were inspected across 106 unique in iduals from four different repositories. Bioacoustic analysis was based on 134 range-wide sound recordings. Two types of calls, territorial calls and alarm calls, were analyzed using different sets of parameters. Principal component analysis and the Isler Criterion were applied to the measurements. Playback trials were conducted to explore the levels of response of each taxon to the call types of the other taxa. The territorial call of concinna exhibits a distinct two-element motif, while elegans , maria and virginalis utter a three-element motif in which the first two elements are given in quick succession. On the other hand, vigorsii , produces both two-element and three-element motifs with longer breaks in between elements. As further corroborated by the playback trials, the three taxa elegans , virginalis and maria form a tight vocal cluster, whereas each concinna and vigorsii are distinct. The alarm call turned out to be less diagnostic even though most taxa did roughly separate into different vocal clusters. Morphometric analysis failed to produce strong differences, but plumage distinctions among multiple taxa are pronounced. We suggest splitting the Elegant Pitta into three biological species based on bioacoustic and—less so—plumage evidence: (1) Temminck’s Elegant Pitta P. elegans (including subspecies elegans , virginalis and maria ), (2) Wallace’s Elegant Pitta P. concinna (monotypic), and (3) Banda Elegant Pitta P. vigorsii (monotypic).
Publisher: Lee Kong Chian Natural History Museum, National University of Singapore
Date: 2019
Publisher: Indonesian Institute of Sciences
Date: 30-06-2020
DOI: 10.14203/TREUBIA.V47I1.3872
Abstract: Southeast Asian avifauna is under threat from both habitat loss and illegal poaching, yet the region’s rich bio ersity remains understudied. Here, we uncover cryptic species-level ersity in the Sunda Blue Robin (Myiomela diana), a songbird complex endemic to Javan (subspecies diana) and Sumatran (subspecies sumatrana) mountains. Taxonomic inquiry into these populations has previously been h ered by a lack of DNA material and the birds’ general scarcity, especially sumatrana which is only known from few localities. We demonstrate fundamental bioacoustic differences in courtship song paired with important distinctions in plumage saturation and tail length that combine to suggest species-level treatment for the two taxa. Treated separately, both taxa are independently threatened by illegal poaching and habitat loss, and demand conservation action. Our study highlights a case of underestimated avifaunal ersity that is in urgent need of revision in the face of imminent threats to species survival.
Publisher: Oxford University Press (OUP)
Date: 06-04-2021
DOI: 10.1093/ORNITHOLOGY/UKAB010
Abstract: The ornithological world has 4 global checklists (as of early 2020). While 3 follow the results of peer-reviewed research at varying pace and conservatism, the HBW/BirdLife checklist, which is adopted by the global Red List authority, has implemented Tobias et al.’s (2010) 7-point scoring system to overhaul global ornithological treatment. Critically received in some academic quarters, this scoring system is lauded by other ornithologists for its simplicity and reproducibility, a claim that remains to be tested. We subjected 26 ornithologists to a set of 48 bird skins belonging to 20 controversial taxonomic complexes and observed a wide variance in scoring results, in most cases straddling anywhere from far below to above the species threshold of the 7-point rule and casting doubt on claims of high reproducibility. For a detailed assessment of genuine taxonomic discord, we compared the taxonomic coverage of the avifauna of the Indonesian Archipelago (comprising ~1,400 species) between the HBW/BirdLife checklist, other major authorities, and the peer-reviewed literature. We detected that controversial treatments supported by the 7-point rule but at odds with the peer-reviewed literature predominantly refer to lumps, not splits, which are the usual subject of modern taxonomic quarrels. Notably, the method tends to unite morphologically (and sometimes vocally) cryptic forms into single larger species because of its inability to accommodate molecular and massive bioacoustic datasets that would indicate otherwise. On the other hand, the 7-point rule has produced numerous novel proposals for splits that may or may not be corroborated by future peer-reviewed inquiry. We recommend the 7-point rule as one of the multiple unofficial exploratory tools to flag cases of potentially cryptic species requiring further inquiry, but we advise against its adoption by other taxonomic authorities and the ornithological community.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Wiley
Date: 25-09-2022
DOI: 10.1111/ZSC.12568
Abstract: Morphology has been a leading taxonomic guiding light to systematists for the last couple of hundred years. However, the genetic and – more recently – genomic revolution have produced numerous demonstrations of erroneous classifications that were based on labile morphological traits. We used thousands of genome‐wide markers to shed light on evolutionary dynamics in a confusing and taxonomically obscure group of Asian Cyornis flycatchers. Using genomic data, we corroborated recent findings based on three mitochrondrial and five nuclear genes that the two taxa hainanus and klossi which were previously treated as separate species ( Cyornis hainanus and Cyornis rubeculoides klossi , respectively) are genomically homogeneous and form a single species, C. hainanus . We also uncovered a novel case of interbreeding between C. hainanus and a non‐sister species, C. glaucicomans , illustrating these flycatchers' ability to hybridise in marginal situations even after substantial times of ergence. Our study illustrates how genome‐wide loci can shed light on complicated taxonomic problems, resulting in a better integration of phenotypic and genotypic data.
Publisher: Elsevier BV
Date: 17-09-2019
DOI: 10.1186/S40657-019-0175-4
Abstract: The taxonomy of the Collared Owlet ( Glaucidium brodiei ) species complex is confused owing to great in idual variation in plumage colouration seemingly unrelated to their distribution. Although generally recognised as a single species, vocal differences among the subspecies have been noted by field recordists. However, there is no study assessing the vocal differences among these four subspecies. We obtained 76 sound recordings of the G. brodiei species complex comprising all four subspecies. We conducted bioacoustic examinations using principal component analysis and the Isler criterion to quantitatively test species boundaries within the G. brodiei complex. In addition, we compared plumage colouration among 13 specimens of the G. brodiei complex deposited at the Natural History Museum at Tring, UK and the Lee Kong Chian Natural History Museum, Singapore to ascertain the presence of plumage differences across taxa. We found the Bornean and Sumatran populations vocally similar to each other, but distinctly different from the mainland and Taiwan populations. The vocal pattern seems to corroborate plumage distinctions in the colouration of neck collars: the Bornean and Sumatran taxa share a white neck collar, whereas the continental and Taiwan taxa share a rufous neck collar. We propose the taxonomic elevation of the Sumatran and Bornean populations to species level as Sunda Owlet G. sylvaticum , with one subspecies on Sumatra ( G. s. sylvaticum ) and Borneo ( G. s. borneense ) each. Our study corroborates the importance of bioacoustics in ascertaining species boundaries in non-passerines, and emphasises the significance of incorporating multiple species delimitation approaches when making taxonomic decisions.
Publisher: Springer Science and Business Media LLC
Date: 03-12-2019
DOI: 10.1038/S41598-019-54715-9
Abstract: Intracontinental biotic isions across the vast Palaearctic region are not well-characterized. Past research has revealed patterns ranging from a lack of population structure to deep ergences along varied lines of separation. Here we compared biogeographic patterns of two Palaearctic shorebirds with different habitat preferences, Whimbrel ( Numenius phaeopus ) and Eurasian curlew ( N. arquata ). Using genome-wide markers from populations across the Palaearctic, we applied a multitude of population genomic and phylogenomic approaches to elucidate population structure. Most importantly, we tested for isolation by distance and visualized barriers and corridors to gene flow. We found shallow Palaearctic population structure in subpolar bog and tundra-breeding whimbrels, consistent with other species breeding at a similarly high latitude, indicating connectivity across the tundra belt, both presently and during southward shifts in periods of global cooling. In contrast, the temperate grassland-breeding Eurasian curlew emerged in three distinct clades corresponding to glacial refugia. Barriers to gene flow coincided with areas of topographic relief in the central Palaearctic for whimbrels and further east for Eurasian curlews. Our findings highlight the interplay of historic and ecological factors in influencing present-day population structure of Palaearctic biota.
No related grants have been discovered for Elize Ng.