Populations of the Bornean gliding lizard, Draco cornutus, differ markedly in the colour of their gliding membranes. They also differ in local vegetation type (mangrove forest versus lowland rainforest) and consequently, the colour of falling leaves (red and brown/black in mangrove versus green, brown and black in rainforest). We show that the gliding membranes of these lizards closely match the colours of freshly fallen leaves in the local habitat as they appear to the visual system of birds (their probable predators). Furthermore, gliding membranes more closely resembled colours of local fallen leaves than standing foliage or fallen leaves in the other population's habitat. This suggests that the two populations have diverged in gliding membrane coloration to match the colours of their local falling leaves, and that mimicking falling leaves is an adaptation that functions to reduce predation by birds.
Loss of dispersal typifies island biotas, but the selective processes driving this phenomenon remain contentious. This is because selection via, both indirect (e.g. relaxed selection or island syndromes) and direct (e.g. natural selection or spatial sorting) processes may be involved, and no study has yet convincingly distinguished between these alternatives. Here, we combined observational and experimental analyses of an island lizard, the Komodo dragon (Varanus komodoensis, the world's largest lizard), to provide evidence for the actions of multiple processes that could contribute to island dispersal loss. In the Komodo dragon, concordant results from telemetry, simulations, experimental translocations, mark-recapture, and gene flow studies indicated that despite impressive physical and sensory capabilities for long-distance movement, Komodo dragons exhibited near complete dispersal restriction: individuals rarely moved beyond the valleys they were born/captured in. Importantly, lizard site-fidelity was insensitive to common agents of dispersal evolution (i.e. indices of risk for inbreeding, kin and intraspecific competition, and low habitat quality) that consequently reduced survival of resident individuals. We suggest that direct selection restricts movement capacity (e.g. via benefits of spatial philopatry and increased costs of dispersal) alongside use of dispersal-compensating traits (e.g. intraspecific niche partitioning) to constrain dispersal in island species.
We provide an integrative taxonomic analysis of the Lipinia vittigera species complex from mainland Southeast Asia. Based on examination of external morphology, color pattern, and 681 base pairs of the cytochrome oxidase subunit I (COI) mitochondrial gene, we demonstrate the presence of four morphologically distinct lineages of Lipinia in Vietnam, Cambodia, Thailand, and Malaysia, showing a sequence divergence ranging 15.5%-20.4%. All discovered lineages are discretely diagnosable from one another by a combination of scalation traits and color patterns. A review of the published distribution data and a re-examination of available type material revealed the following results:(1) distribution of L. vittigera (Boulenger, 1894) sensu stricto is restricted to Sundaland and the Thai-Malay Peninsula south of the Isthmus of Kra; (2) L. microcercus (Boettger, 1901) stat. nov. is elevated to full species rank; the species has a wide distribution from central and southern Vietnam across Cambodia to eastern Thailand; we regard Lygosoma vittigerum kronfanum Smith, 1922 and Leiolopisma pranensis Cochran, 1930 as its junior synonyms; (3) Lipinia trivittatasp. nov. occurs in hilly areas of southern Vietnam, Cambodia, and eastern Thailand; and (4) Lipinia vassilievisp. nov. is currently known only from a narrow area along the Vietnamese-Cambodian border in the foothills of the central Annamite Mountain Range. We further provide an identification key for Lipinia occurring in mainland Southeast Asia.
Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.
A new species of gekkonid, Hemiphyllodactylus chiangmaiensis sp. nov., from northwestern Thailand is separated from all other species of Hemiphyllodactylus by a set of features including: a maximum SVL of 41.2 mm; 8-12 chin scales extending transversely from unions of second and third infralabials and posterior margin of mental; lamellar formula on hand 3-3-3-3 or 3-4-3-3; lamellar formula on foot 3-3-3-3 or 3-4-4-4; continuous precloacal and femoral pores; a unique dorsal color pattern; and caecum and oviducts pigmented. These characters place this species in the speciose H. typus group. Hemiphyllodactylus chiangmaiensis sp. nov. fills a biogeographical hiatus in the distribution of this genus across northern Indochina.
A new insular species Cnemaspis bidongensis sp. nov. (Squamata: Gekkonidae), is described from Pulau Bidong, Terengganu, Peninsular Malaysia and bears a unique suite of morphological and color pattern characters that differentiate it from all other congeners. Cnemaspis bidongensis sp. nov. is the sister species to C. kendallii (Gray) and represents the fifth insular endemic species of Cnemaspis on archipelagos along the east coast of Peninsular Malaysia. This species survived massive deforestation of the small island of Bidong (260 ha) from the mid 1970s to the early 1990s when the island served as a Vietnamese refugee camp and harbored as many as 40,000 people at one time. We hypothesize that this species' generalized lifestyle contributed to its survival, allowing it to seek refuge in rocky microhabitats.
Nest predation is the main cause of hatching failure for many turtle populations. For green turtles (Chelonia mydas) nesting at Chagar Hutang in Redang Island, Malaysia, Asian water monitors (Varanus salvator) are a potential nest predator. However, no studies have documented the space use of this species in coastal habitat adjacent to a sea turtle nesting beach to assess its potential impact on turtle nests. Here, we used Global Positioning System (GPS) data loggers to quantify space use of Asian water monitors in order to establish the extent to which they use sea turtle nesting areas. Asian water monitors had a diurnal activity pattern and spent most of their time in rain forest habitat behind the sea turtle nesting beach. The home range occupied by Asian water monitors varied between 0.015 and 0.198 km2 calculated by the Kernel Brownian Bridge method. The space use patterns of individual Asian water monitors varied between individuals. Two males had relatively small home ranges, whereas one male and the female had a relatively large home range. Because tracked Asian water monitors in this study rarely visited the sea turtle nesting areas, it is probable that only a few individuals are responsible for opening nests.
Human land use is continuously altering the natural environment, yet the greater ecological implications of this change for many groups that are key to healthy ecosystem functioning remains uncharacterised in the tropics. Terrestrial scavenging vertebrates are one such group, providing integral ecosystem services through the removal of carrion which is a crucial component of both nutrient cycling and disease dynamics. To explore how anthropogenic processes may affect forest scavengers, we investigated the changes in the relative occupancy of two important terrestrial scavengers along a gradient of land use intensity, ranging from protected forest to oil palm plantation in Borneo. We found the Malay civet (Viverra tangalunga) had highest, albeit variable, occupancy in areas of low land use intensity and the Southeast Asian water monitor (Varanus salvator macromaculatus) had highest occupancy in areas of high land use intensity. Land use had no effect on the combined occupancy of the two species. In high land use intensity sites, individual water monitors were larger and had better body condition, but at population level had a highly biased sex ratio with more males than females and increased signs of intraspecific conflict. We did not assess scavenging rate or efficiency as a process, but the high occupancy rates and apparent health of the scavengers in high land use intensity landscapes suggests this ecological process is robust to land use change.
An integrative taxonomic analysis used to identify a new population of Bronchocela from Phuket Island, Thailand indicates it is conspecific with B. rayaensis from the Langkawi Archipelago of northwestern Peninsular Malaysia. An additional specimen photographed from Khura Buri District, Phang-nga Province is also considered to be B. rayaensis and represents a northern range extension of 295 km from the Langkawi Archipelago.
Phylogenetic analyses based on the mitochondrial gene ND2 and its flanking tRNAs indicate the diminutive upland and insular species Sphenomorphus bukitensis, S. butleri, S. langkawiensis, S. perhentianensis, and S. temengorensis form a monophyletic group that is phylogenetically embedded within the Southeast Asian genus Tytthoscincus. The analyses also indicate that a new swamp-dwelling skink from the Bukit Panchor State Park, Pulau Pinang, Peninsular Malaysia is the sister species to the swamp-dwelling species S. sibuensis from Pulau Sibu, Johor and Singapore and that these two are also embedded in the genus Tytthoscincus. By transferring the two Peninsular Malaysian clades of Sphenomorphus into the genus Tytthoscincus, the monophyly of the latter is maintained. The new species T. panchorensis sp. nov. can be distinguished from all other species of Tytthoscincus by having a unique combination of morphological and color pattern characteristics.
An integrative taxonomic analysis based on the mitochondrial gene ND2 and its flanking tRNAs, morphology, and color pattern indicates that a newly discovered gecko described herein as Hemiphyllodactylus cicak sp. nov. from Penang Hill on the Island of Penang, Peninsular Malaysia is a member of the H. harterti group. Hemiphyllodactylus cicak sp. nov. is most closely related to the clade composed of the sister species H. harterti from Bukit Larut, Perak in the Bintang Mountain Range and H. bintik from Gunung Tebu, Terengganu from the Timur Mountain Range. These three allopatric species form a monophyletic group that extends approximately 270 km across three isolated mountain ranges in northern Peninsular Malaysia. The molecular analysis also indicates that H. titiwangsaensis from the Titiwangsa Mountain Range is composed of three genetically distinct allopatric populations. The southern two populations from Fraser's Hill and Genting Highlands, Pahang have an uncorrected pairwise sequence divergence of 3.5% whereas these two populations have 12.4 and 12.8 % sequence divergences, respectively, from the northern population at Cameron Highlands, Pahang. Although the high sequence divergence clearly distinguishes the southern two populations from the former as a different species, all three populations are morphologically indistinguishable, leading to the hypothesis of a true, cryptic speciation event.
A new species of Bent-toed Gecko Cyrtodactylus guakanthanensis sp. nov. of the C. sworderi complex is described from a limestone forest in Perak, Peninsular Malaysia whose karst formations at the type locality are within an active quarry. Cyrtodactylus guakanthanensis sp. nov. can be distinguished from all other Sundaland species by having the following suite of character states: adult SVL 77.7-82.2 mm; moderately sized, conical, weakly keeled, body tubercles; tubercles present on occiput, nape, and limbs, and extend posteriorly beyond base of tail; 37-44 ventral scales; no transversely enlarged, median, subcaudal scales; proximal subdigital lamellae transversely expanded; 19-21 subdigital lamellae on fourth toe; abrupt transition between posterior and ventral femoral scales; enlarged femoral scales; no femoral or precloacal pores; precloacal groove absent; wide, dark postorbital stripes from each eye extending posteriorly to the anterior margin of the shoulder region thence forming a transverse band across the anterior margin of the shoulder region; and body bearing five (rarely four) wide, bold, dark bands. Destruction of the karst microhabitat and surrounding limestone forest will extirpate this new species from the type locality and perhaps drive it to complete extinction given that it appears to be restricted to the particular microhabitat structure of the type locality and is not widely distributed throughout the karst formations. As with plants and invertebrates, limestone forests are proving to be significant areas of high herpetological endemism and should be afforded special conservation status rather than turned into cement.
A new species of limestone cave-adapted gecko of the Cyrtodactylus pulchellus complex, C. hidupselamanya sp. nov., is described from an isolated karst formation at Felda Chiku 7, Kelantan, Peninsular Malaysia. This formation is scheduled to be completely quarried for its mineral content. From what we know about the life history of C. hidupselamanya sp. nov., this will result in its extinction. A new limestone forest-adapted species, C. lenggongensis sp. nov., from the Lenggong Valley, Perak was previously considered to be conspecific with C. bintangrendah but a re-evaluation of morphological, color pattern, molecular, and habitat preference indicates that it too is a unique lineage worthy of specific recognition. Fortunately C. lenggongensis sp. nov. is not facing extinction because its habitat is protected by the UNESCO Archaeological Heritage of the Lenggong Valley due to the archaeological significance of that region. Both new species can be distinguished from all other species of Cyrtodactylus based on molecular evidence from the mitochondrial gene ND2 and its flanking tRNAs as well as having unique combinations of morphological and color pattern characteristics. Using a time-calibrated BEAST analysis we inferred that the evolution of a limestone habitat preference and its apparently attendant morphological and color pattern adaptations evolved independently at least four times in the C. pulchellus complex between 26.1 and 0.78 mya.