Cryptic diversity: Two morphologically similar species of invasive apple snail in Peninsular Malaysia

Invasive snails in the genus Pomacea have spread across Southeast Asia including Peninsular Malaysia. Their effects on natural and agricultural wetlands are appreciable, but species-specific effects are less clear because of morphological similarity among the species. Our objective was to establish diagnostic characteristics of Pomacea species in Malaysia using genetic and morphological criteria. The mitochondrial COI gene of 52 adult snails from eight localities in Peninsular Malaysia was amplified, sequenced, and analysed to verify species and phylogenetic relationships. Shells were compared using geometric morphometric and covariance analyses. Two monophyletic taxa, P. canaliculata and P. maculata, occurred in our samples. The mean ratio of shell height: aperture height (P = 0.042) and shell height: shell width (P = 0.007) was smaller in P. maculata. P. maculata co-occurred with P. canaliculata in five localities, but samples from three localities contained only P.canaliculata. This study is the first to confirm the presence of two of the most invasive species of Pomacea in Peninsular Malaysia using a molecular technique. P. canaliculata appears to be the more widespread species. Despite statistical differences, both quantitative and qualitative morphological characteristics demonstrated much interspecific overlap and intraspecific variability; thus, shell morphology alone cannot reliably verify species identity. Molecular techniques for distinguishing between these two highly invasive Pomacea species are needed to understand their specific ecological niches and to develop effective protocols for their management

The efficiency of universal mitochondrial DNA barcodes for species discrimination of Pomacea canaliculata and Pomacea maculata

Invasive apple snails, Pomacea canaliculata and P. maculata, have a widespread distribution globally and are regarded as devastating pests of agricultural wetlands. The two species are morphologically similar, which hinders species identification via morphological approaches and species-specific management efforts. Advances in molecular genetics may contribute effective diagnostic tools to potentially resolve morphological ambiguity. DNA barcoding has revolutionized the field of taxonomy by providing an alternative, simple approach for species discrimination, where short sections of DNA, the cytochrome c oxidase subunit I (COI) gene in particular, are used as ‘barcodes’ to delineate species boundaries. In our study, we aimed to assess the effectiveness of two mitochondrial markers, the COI and 16S ribosomal deoxyribonucleic acid (16S rDNA) markers for DNA barcoding of P. canaliculata and P. maculata. The COI and 16S rDNA sequences of 40 Pomacea specimens collected from six localities in Peninsular Malaysia were analyzed to assess their barcoding performance using phylogenetic methods and distance-based assessments. The results confirmed both markers were suitable for barcoding P. canaliculata and P. maculata. The phylogenies of the COI and 16S rDNA markers demonstrated species-specific monophyly and were largely congruent with the exception of one individual. The COI marker exhibited a larger barcoding gap (6.06–6.58%) than the 16S rDNA marker (1.54%); however, the magnitude of barcoding gap generated within the barcoding region of the 16S rDNA marker (12-fold) was bigger than the COI counterpart (approximately 9-fold). Both markers were generally successful in identifying P. canaliculata and P. maculata in the similarity-based DNA identifications. The COI + 16S rDNA concatenated dataset successfully recovered monophylies of P. canaliculata and P. maculata but concatenation did not improve individual datasets in distance-based analyses. Overall, although both markers were successful for the identification of apple snails, the COI molecular marker is a better barcoding marker and could be utilized in various population genetic studies of P. canaliculata and P. maculata

Secondary forest within a timber plantation concession in Borneo contributes to a diverse mammal assemblage

Commercial tree plantations of fast-growing species have become increasingly important in Southeast Asia to meet global demand for wood and wood fiber products. There is a growing need to understand more about their value for wildlife and how they can be managed for biodiversity. We evaluated the effects of landscape attributes on mammal communities in a timber concession consisting of 83 % secondary forest and 17 % tree plantations in northern Sabah, Malaysia. Using camera traps, we compared mammalian species assemblages of secondary forest and commercial tree plantation stands and identified habitat predictors associated with total mammal species detections and species richness in the landscape mosaic. We used 87 camera stations deployed for 23 days across two major land-use types: 62 sites in secondary forest (previously logged natural forest) and 25 sites in tree plantations. We evaluated variation in species richness in these two major land-use categories and assessed the effects of natural and anthropogenic predictors on variation in total mammal detections and species richness. We detected at least 23 large and medium-sized mammal species over 2035 trap nights. Fourteen of those species were classified as threatened or near-threatened by the International Union for the Conservation of Nature. Rarefaction did not reveal differences in mammal species richness or diversity between camera sites placed in tree plantations and secondary forests, likely because most camera sites in tree plantations were close to secondary forest and comprised < 30 % of all sites. However, generalized linear models indicated lower mammal diversity as proportions of tree plantation and proximity to human settlements increased. Total mammal records, including those of threatened mammals, increased with greater proportions of secondary forest. Retention of larger tracts of secondary forest around plantation areas appears to be important to maintain mammalian species richness and contributes to the conservation value of commercial timber plantations. These findings may assist in the management of mammals of conservation concern and implementation of adaptive management plans to enhance biodiversity conservation in commercial plantations

Distribution and environmental associations of invasive freshwater Pomacea snails in Peninsular Malaysia

Freshwater habitats represent one of the most important ecosystems for sustaining terrestrial biodiversity and human societies, but are particularly vulnerable to the effects of pollution and species invasions. Two highly invasive species of freshwater snail, Pomacea canaliculata and P. maculata, occur in Malaysia, but apart from their impacts on rice agriculture, little information exists about their distribution and associated environmental factors. We investigated the distribution of these two species and associated environmental gradients by surveying 550 quadrats at 108 geographic locations in Malaysia and measuring selected water parameters, including the species richness of co-occurring gastropods. Sampling locations comprised five different habitats: rivers and streams, lakes and ponds, reservoirs, waterfalls, and rice fields. We used DNA sequencing and rapid

Invasive apple snails in wetlands of Selangor, Malaysia: Species, distribution, and ecological associations

Apple snails in the genus Pomacea are among the worst invasive species in Southeast Asia. Our objectives were to survey a selection of different wetlands in Selangor for Pomacea, verify which species of Pomacea occurred in that location, and assess basic environmental parameters associated with their presence and relative abundance. Aquatic parameters including pH and concentrations of selected electrolytes were measured at 25 wetland sites distributed among eight localities in Selangor. DNA from snails collected at each locality was extracted and the mitochondrial cytochrome c oxidase subunit I (COI) was sequenced. We detected two of the most successful invaders of this genus: P. canaliculata was found in five localities and P. maculata in two. Both pH and calcium ion concentrations were negatively associated with Pomacea presence. Pomacea were absent in brackish wetlands with high pH and calcium concentrations reflecting possible physiological intolerance or that dispersal into these habitats has yet to occur. P. maculata is reported to tolerate pH as low as 4.5-6; thus most freshwater wetlands in Selangor and most of Malaysia can potentially be invaded. Pomacea canaliculata and P. maculata have demonstrated remarkable capacity for depleting aquatic macrophytes and may cause rapid changes in aquatic plant communities with potential impacts to wetland state and function. Public awareness and environmentally safe recommendations to mitigate the reproduction and spread of this invasive snail is needed for protecting the biodiversity and health of natural wetlands

Carnivore hotspots in Peninsular Malaysia and their landscape attributes

Mammalian carnivores play a vital role in ecosystem functioning. However, they are prone to extinction because of low population densities and growth rates, and high levels of persecution or exploitation. In tropical biodiversity hotspots such as Peninsular Malaysia, rapid conversion of natural habitats threatens the persistence of this vulnerable group of animals. Here, we carried out the first comprehensive literature review on 31 carnivore species reported to occur in Peninsular Malaysia and updated their probable distribution. We georeferenced 375 observations of 28 species of carnivore from 89 unique geographic locations using records spanning 1948 to 2014. Using the Getis-Ord Gi*statistic and weighted survey records by IUCN Red List status, we identified hotspots of species that were of conservation concern and built regression models to identify environmental and anthropogenic landscape factors associated with Getis-Ord Gi* z scores. Our analyses identified two carnivore hotspots that were spatially concordant with two of the peninsula’s largest and most contiguous forest complexes, associated with Taman Negara National Park and Royal Belum State Park. A cold spot overlapped with the southwestern region of the Peninsula, reflecting the disappearance of carnivores with higher conservation rankings from increasingly fragmented natural habitats. Getis-Ord Gi* z scores were negatively associated with elevation, and positively associated with the proportion of natural land cover and distance from the capital city. Malaysia contains some of the world’s most diverse carnivore assemblages, but recent rates of forest loss are some of the highest in the world. Reducing poaching and maintaining large, contiguous tracts of lowland forests will be crucial, not only for the persistence of threatened carnivores, but for many mammalian species in general

Anthropogenic edge effects in habitat selection by sun bears in a protected area

Wildlife populations in southeast Asia are increasingly experiencing a broad array of anthropogenic threats, and mammalian carnivores are particularly vulnerable. Populations of the Malayan sun bear Helarctos malayanus are estimated to have declined by 30% over the last 30 years from forest conversion to industrial plantations and mortality associated with human–bear conflicts and illegal wildlife trade. However, the effects of industrial plantations on habitat selection and activity patterns of mammals that live at the protected area-plantation interface, including sun bears, are not well known. We investigated habitat selection and activity patterns of sun bears in Tabin Wildlife Reserve in Sabah, Malaysia. We deployed 83 remote camera sites to record sun bear detections during two sampling periods (2012–2013 and 2017). We used generalized linear models to examine relationships between sun bear presence and site covariates representing physical, environmental and anthropogenic elements of the landscape. Relative probability of sun bear presence was positively associated with distance to roads and elevation. Because most roads were on the reserve boundary and often associated with oil palm plantations, proximity to roads likely served as a surrogate measure of human accessibility and activity in peripheral areas of the reserve. Supporting that interpretation, sun bears close to the reserve boundary were primarily active at night, whereas daytime activity was more common for bears in the interior. Our findings indicate that sun bears alter behaviour and habitat selection likely in response to anthropogenic activities at the edges of Tabin Wildlife Reserve (112 200 ha). Because the ratio of edge to interior increases steeply with declining habitat area, smaller protected areas bordered by plantations are predicted to have greater impacts on sun bear behaviour and, potentially, population persistence. Effective conservation actions may benefit from management to improve the security of edge habitats for sun bears and other vulnerable species

Female philopatry and spatial organization in the raccoon (Procyon lotor)

Among mammals, some of the most common types of cohesive social groupings originate form natal philopatry through the extended mother family. The recognition that females among some solitary mammals demonstrate natal philopatry suggests that an important part of understanding the evolution of social groupings in mammals is through establishing the conditions that lead to natal philopatry in solitary species. The North American raccoon, Procyon lotor, is a relatively solitary carnivore of the Procyonidae, a family that demonstrates both variability and flexibility in the nature and degree of sociality. This dissertation examines the conditions surrounding natal philopatry in a raccoon population in east Tennessee with the goals of identifying 1) the population correlates and individual consequences of female philopatry, and 2) the influence of philopatry and kinship on female spatial organization. I gathered over three years of radio telemetry and mark-recapture data to obtain information on raccoon population ecology and female spatial relationships on the Oak Ridge Reservation. Most female offspring persisted on the natal area beyond dependence and beyond their mother’s next breeding episode. Most dispersal was in the early Spring (Jan — Mar) when mortality was highest among philopatric females. Population density of raccoons on the study area was high relative to other raccoon populations in east Tennessee, as was the proportion of females in older age classes. Individual and population characteristics of young females at White Oak Lake indicated that philopatry under these demographic conditions was costly. Although female raccoons are physiologically capable of reproduction at one year, lower body weight, delated reproduction and higher mortality in younger females relative to older females suggested that competition from older females limited free access to food and breeding opportunities. The presence of a yearling daughter within the home range did not seem to incur reproductive costs to mothers. At least 50% of mothers who shared space with yearling daughters became pregnant the following year. No philopatric daughters became pregnant when their mothers were alive on the natal area. DNA amplification employing primers of arbitrary sequence (RAPDs) indicated that female philopatry in raccoons led to a greater likelihood that neighbors were more related than expected by chance. Genetic distance based on RAPD band frequency was positively associated with spatial distance among females. Genetic similarity was positively associated with the extent of home range overlap. Genetic similarity was positively associated with the extent of home range overlap. Philopatry seemed biased toward females; average female-female similarities at White Oak Lake were greater than average male-male similarities or average male-female similarities. High home range overlap among females with low and moderate levels of band sharing suggested that maternal inheritance of space was not a prerequisite for home range sharing. High home range overlap was less common among parous females. Spatial and temporal interaction among females was independent of the percentage of band sharing with most responses to shared areas being random. Individual spacing among most females was high relative to the distances between their activity centers, reflecting the predominantly solitary nature of female raccoons. Hypotheses explaining the formation of cooperative social groups in carnivores invoke ecological, demographic and behavioral factors that influence an individual’s reproductive opportunities and the probability of philopatry. Certain aspects of female philopatry in raccoons bear a closer resemblance to circumstances hypothesized to promote natal philopatry in some social carnivores

Phylogram shows BI analysis of <i>Pomacea canaliculata</i> and <i>P</i>. <i>maculata</i> in Peninsular Malaysia with other <i>Pomacea</i> species from introduced (USA, Japan) and native (South America) ranges.

<p>Bayesian posterior probabilities are shown for each clade. <i>Pomacea scalaris</i> and <i>Pomacea diffusa</i> were selected to root the tree. Only nodes with Bayesian posterior probabilities (PP) greater than 0.5 as a validity supported clade for the construction of a 50% majority rule consensus tree.</p

Comparison of qualitative characteristics between 26 <i>Pomacea canaliculata</i> and 26 <i>P</i>. <i>maculata</i> shells collected in Peninsular Malaysia.

<p>Comparison of qualitative characteristics between 26 <i>Pomacea canaliculata</i> and 26 <i>P</i>. <i>maculata</i> shells collected in Peninsular Malaysia.</p