Patterns of avian diversification in Borneo: The case of the endemic Mountain Black-eye (Chlorocharis emiliae)

Abstract

The Mountain Black-eye (Chlorocharis emiliae) is an endemic white-eye (Zosteropidae) of Borneo with a unique ''sky island'' distribution. We compared mitochondrial ND2, ND3, Cytb, and control region DNA sequences (2,194 nucleotides) to study the phylogeographic relationships of five populations of this species that span its range: Mounts Kinabalu, Trus Madi, Murud, Mulu, and Pueh. These comparisons showed that black-eyes are divided into two main clades that correspond generally to subspecific morphological groups: one in Sabah, Malaysia (Kinabalu and Trus Madi), and one in Sarawak, Malaysia (Murud, Mulu, and Pueh). The genetic and morphologic subdivision of black-eyes disputes the expected merging of populations during the Last Glacial Maximum (LGM), when montane forest presumably expanded and provided the opportunity for currently isolated populations to intermingle. Instead the genetic aging of black-eye populations indicates they diversified long before the LGM, and either did not expand sufficiently in range during the LGM to reach one another, or were reproductively isolated by the time of the LGM and thus prevented from interbreeding. Moreover, the subdivision between black-eyes in Sabah and Sarawak means that this species (and probably several other montane species) has a phylogeographic structure remarkably similar to Borneo's lowland bird populations, which are presumed to have evolved under different paleo-geographic conditions. The similar phylogeographic pattern found in both montane and lowland species requires that we rethink the causes of bird population diversification on the island of Borneo. Keywords: Greater Sunda Islands, last glacial maximum, montane avifauna, phylogeography, refugia, sky islands, ZosteropidaePatrons de diversification aviaireà Bornéo: Le cas d'une espèce endémique, Chlorocharis emiliae RÉSUMÉ Chlorocharis emiliae est une espèce endémique de Zosteropidae de Bornéo ayant une répartition unique de type ''sky island.'' Nous avons comparé les séquences d'ADN mitochondrial ND2, ND3, Cytb, et de la région de contrôle (2,194 nucléotides) afin d'étudier les relations phylogéographiques de cinq populations de cette espèce qui couvrent toute son aire de répartition: Les Monts Kinabalu, Trus Madi, Murud, Mulu, et Pueh. Ces comparaisons ont montré que C. emiliae se divise en deux principaux clades qui correspondent généralement aux groupes morphologiques sousspécifiques: unà Sabah, en Malaisie (Kinabalu et Trus Madi) et unà Sarawak, en Malaisie (Murud, Mulu, et Pueh). La subdivision génétique et morphologique de C. emiliae conteste l'hypothèse de fusion des populations au cours du dernier maximum glaciaire (DMG), lorsque la forêt montagnarde s'est vraisemblablement développée et a fourni aux populations actuellement isolées l'occasion de se mélanger. Au lieu de cela, le vieillissement génétique des populations de C. emiliae indique qu'elles se sont diversifiées bien avant le DMG, et que leur aire de répartition ne s'est pas suffisammentélargie au cours du DMG pour se rejoindr...

The Panjange nigrifrons group in Borneo (Araneae: Pholcidae): high diversity in Sarawak, apparent absence in Sabah

“…Obviously, large sampling gaps remain, and a meaningful interpretation will have to build on a much more intense sampling including Kalimantan. However, data on better studied organisms such as birds have also supported a biogeographical divide between Sabah and Sarawak despite continuous rainforest (Gawin et al 2014;Sheldon et al 2015). These authors mainly suggest historical reasons for this pattern, such as early Pleistocene rainforest refugia in Sabah versus dry habitats in Sarawak (at that time part of central Sundaland).…”

“…data). In this contribution we will deal with the taxonomy of the Panjange nigrifrons group, we provide basic microhabitat data, and we document a biogeographic peculiarity that has been known in other groups such as birds (e.g., Gawin et al 2014;Sheldon et al 2015) but to our knowledge not in spiders: an apparent distributional limit between Sarawak and Sabah. a.s.l.…”

Genomic phylogeography of the endemic Mountain Black‐eye of Borneo (Chlorocharis emiliae): montane and lowland populations differ in patterns of Pleistocene diversification

“…As in lowland studies, Gawin et al . () found this bird species to be subdivided east‐to‐west approximately at the Sabah‐Sarawak border. However, such a pattern in montane taxa presents a conundrum.…”

“…Based on plumage, it is placed in a monotypic genus, but recent phylogenetic analysis has shown it to be within the white‐eye genus Zosterops in the babbler family Zosteropidae (Moyle et al ., , ). C. emiliae has a sky‐island distribution unique among Bornean birds (Gawin et al ., ). In Borneo's central mountain chain, this species occurs only on peaks above 1800 m in elevation.…”

“…On Borneo, the only investigation of montane animal phylogeography that covers the breadth of the island is the study by Gawin et al . () of Mountain Black‐eye ( Chlorocharis emiliae ). As in lowland studies, Gawin et al .…”