Books by Mohd Ridwan Abd Rahman
Papers by Mohd Ridwan Abd Rahman
Presbytis femoralis robinsoni, locally known as the ‘lutong ceneka’, is an endemic femoralis subs... more Presbytis femoralis robinsoni, locally known as the ‘lutong ceneka’, is an endemic femoralis subspecies to the northern part of Peninsular Malaysia and southern Thailand. This langur warrants immediate conservation attention, as it is categorized as Near Threatened by the International Union for Conservation of Nature (IUCN), with a declining numbers of population trend and being threatened with numerous conservation issues.With poor understanding on population status and unresolved conservation framework in Malaysia, data on behavioral ecology such as positional behavior of P. f. robinsoni are non-existent in Malaysia. Thus, this study describes the first record on qualitative aspects of the positional behavior of Robinson’s banded langur (P. f. robinsoni) in the Sungai Sedim Recreation Forest (SSRF), Kedah, Malaysia. The positional behaviors of P. f. robinsoni in SSRF involve sitting, lying, quadrupedal standing, bipedal standing, clinging, and forelimb suspension. These varieties...
Tropical Ecology, 2010
The short nosed fruit bat Cynopterus brachyotis (Muller 1838) is primarily a plant-visiting bat f... more The short nosed fruit bat Cynopterus brachyotis (Muller 1838) is primarily a plant-visiting bat feeding on fruits, flowers and leaf fractions (Funakoshi et al. 1993). It typically roosts in small groups in trees, under banana leaves, palm fronds and man-made structures. It is locally abundant, has a wide distribution throughout South/South East Asia and occupies a variety of habitats including primary and disturbed forest, orchard, mangrove and cultivated areas (Corbet & Hill 1992). C. brachyotis is probably one of the best studied fruit bats in South East Asia. It’s ecology and behavior, especially foraging ecology, has been well explored in Peninsular Malaysia. (Abdullah 2003; Campbell et al. 2006a,b; Campbell et al. 2007; Hodgkison & Balding 2004; Tan et al. 1998). No studies, however, have been carried out on the ecology of this species in Malaysian Borneo. The Peninsular Malaysia and Malaysian Borneo are different in terms of floristics, endemism and flowering phenology. This s...
Journal of Sustainability Science and Management
Biodiversitas Journal of Biological Diversity, Mar 25, 2019
Recent taxonomic reviews have stated the possibility of Bengal Slow Loris (Nycticebus bengalensis... more Recent taxonomic reviews have stated the possibility of Bengal Slow Loris (Nycticebus bengalensis) presence in the Northern part of the Malay Peninsula. This study aims to confirm the presence of the Bengal Slow Loris in Malaysia by sequencing the mitochondrial COI gene from samples collected from Langkawi Island, Peninsular Malaysia, and Borneo. Phylogenetic analyses produced tree topologies that support the grouping of slow loris samples by their localities. The tree topologies further show that slow loris samples from Sarawak and Peninsular Malaysia form two distinct clades. The clade from Peninsular Malaysia was divided into two subclades, Langkawi and Selangor. The Langkawi slow loris subclade includes sequences from GenBank representing N. bengalensis, supported by a high bootstrap value. This mitochondrial DNA finding has a significant contribution to indicate the presence of the Bengal Slow Loris in Malaysia.
Trends in Undergraduate Research
A comprehensive learning experience in biodiversity-related discipline is the only practical way ... more A comprehensive learning experience in biodiversity-related discipline is the only practical way to introduce students into the world of flora. Thus, this study was carried out at Kubah National Park as the park is known for its flora and fauna diversity to investigate plant species which are of timber-related importance. The study identified and documented seven different plant families with 12 species of timber-related usage at Kubah National Park.
Trends in Undergraduate Research, 2019
A comprehensive learning experience in biodiversity-related discipline is the only practical way ... more A comprehensive learning experience in biodiversity-related discipline is the only practical way to introduce students into the world of flora. Thus, this study was carried out at Kubah National Park as the park is known for its flora and fauna diversity to investigate plant species which are of timber-related importance. The study identified and documented seven different plant families with 12 species of timber-related usage at Kubah National Park.
Biodiversitas, 2019
Recent taxonomic reviews have stated the possibility of Bengal Slow Loris (Nycticebus bengalensis... more Recent taxonomic reviews have stated the possibility of Bengal Slow Loris (Nycticebus bengalensis) presence in the Northern part of the Malay Peninsula. This study aims to confirm the presence of the Bengal Slow Loris in Malaysia by sequencing the mitochondrial COI gene from samples collected from Langkawi Island, Peninsular Malaysia, and Borneo. Phylogenetic analyses produced tree topologies that support the grouping of slow loris samples by their localities. The tree topologies further show that slow loris samples from Sarawak and Peninsular Malaysia form two distinct clades. The clade from Peninsular Malaysia was divided into two subclades, Langkawi and Selangor. The Langkawi slow loris subclade includes sequences from GenBank representing N. bengalensis, supported by a high bootstrap value. This mitochondrial DNA finding has a significant contribution to indicate the presence of the Bengal Slow Loris in Malaysia.
Folia Primatologica
The proboscis monkey, Nasalis larvatus, is an endemic species to the island of Borneo. It is list... more The proboscis monkey, Nasalis larvatus, is an endemic species to the island of Borneo. It is listed in the IUCN Red List as Endangered with a decreasing population trend. Nevertheless, biological information, especially on the genetic diversity of the species, is still incomplete. Its fragmented distribution poses difficulties in gathering genetic samples along with its widespread distribution across Borneo. This study aims to determine the genetic variation and structure of N. larvatus with an emphasis on Malaysian Borneo populations to elucidate its gene flow. The genetic variation and structure of N. larvatus were examined using 50 sequences of the 1,434-bp cytochrome oxidase subunit I (COI) gene region of mitochondrial DNA. The COI sequences revealed low genetic variation among N. larvatus populations in Malaysian Borneo. This low genetic variability could be the result of inbreeding pressure that may have occurred due to the absence of population expansion in this species over the last 30,000 years. This is supported in our analysis of molecular variance, which showed that groups of N. larvatus are significantly differentiated possibly due to natural geographic barriers. This study provides baseline information on the genetic diversity among proboscis monkey populations in Borneo for the future genetic assessment of the species.
Morphological analysis of 70 adult individuals of the dusky fruit bat, Penthetor lucasi, was perf... more Morphological analysis of 70 adult individuals of the dusky fruit bat, Penthetor lucasi, was performed using 15 external characters and 18 craniodental characters. Multiple regression and discriminant function analysis (DFA) were applied to test the effects of sex, location and interaction between individuals in the study, and to determine and identify characters which are efficient in differentiating individuals among populations, respectively. Most characters were significantly affected by sex, locality and their interactions. Thus, separate analyses were done for both sexes. The fourth digit metacarpal length (D4MCL) and bulla length (BL) of males, and the hind foot (HF) and dental length (DL) of females, were suggested as the best predictors for the external and craniodental characters, respectively, in differentiating P. lucasi from different localities. These findings establish the morphological morphological variation between three geographically separate populations of P. lucasi within Sarawak. It is suggested that different ecological forces between populations, such as breeding, foraging behaviour, crowding effects and resource availability, could have been the moulding factors behind the observed morphological variations in the different P. lucasi populations.
"The... more "The assessment of bats diversity from two limestone forests in protected areas of Sarawak, the Niah National Park (NP) and the Wind Cave Nature Reserve (NR) were conducted from November 2007 until April 2009. The assessments were aimed to update the current diversity of bats as well as to compile their composition with previous studies done at selected limestone areas in Sarawak. Eight to twelve mist nets and three harp traps were used, with accumulated effort of 572 trap-nights for both the Niah NP and the Wind Cave NR. A total of 1,520 individuals representing 36 species from 17 genera and 10 families were recorded. Penthetor lucasi, Hipposideros cervinus and Cynopterus brachyotis were the three most abundant species captured in both sampling areas. Meanwhile, nine species of bats are new for both localities. Seven out of nine are the new additional records added for the Niah NP, namely, Hipposideros ater, H. bicolor, H. cineraceus, Coelops robinsoni, Rhinolophus trifoliatus, Murina rozendali and Kerivoula hardwickii. While H. ridleyi and Tylonycteris robustula are new record for Wind Cave NR. Morphological analysis of 70 adult individuals of P. lucasi was done using 15 characters and 18 craniodental characters. Multiple regression and discriminant function analysis were applied to test the effects of sex, location and interaction between individuals in this study, and to determine and identify characters which were useful in differentiating individuals among populations. Most characters were significantly affected by sex (TB, D5P1L, GSL, PL, DL, C1BW and C1C1B); locality (E, TB, HF, D4P1L, D5P1L, IOW, MW and GBPL); and their interaction (E, TB, HF, D4P1L, D5P1L, GSL, IOW, MW, PL, PPL, GBPL, and C1C1B). Thus, separate analyses were done for both sexes. The D4MCL and BL of male and HF and DL of female were suggested as the best predictors for the external and craniodental characters respectively in differentiating the P. lucasi of different localities. The findings for the morphological analysis have violated the early assumption of no morphological variation between the populations of P. lucasi. It is suggested that different ecological factor such as breeding, foraging behaviour and resource availability could have influenced the morphological variation of P. lucasi populations. The population genetics of the P. lucasi was inferred using 1,061 base pairs (bp) of the Cytochrome b mitochondrial gene. A total of 77 individuals of P. lucasi were classified a priori accordingly to their localities, namely, Miri, Kuching, Sri Aman and Kelantan populations. The findings showed that the P. lucasi populations were separated into two haplogroups, namely, Haplogroup 1 (containing Miri and Kuching populations) and Haplogroup 2 (the mixture of Miri, Kuching, Sri Aman and Kelantan populations). This separation was supported with high bootstrap values in all four methods of analysis (100% in neighbour joining; 100% in maximum parsimony; 94.9% in maximum likelihood and 100% in Bayesian). The occurrence of two haplogroup was address to unclear status of P. lucasi. High genetic divergence detected between the two haplogroups (3.88%) and separation between the haplogroups is predicted as the ancient events. The historical event includes the multiple colonisation and refugia during ice age period likely the main factors led to such separation. High divergence within the Miri (0.01 - 4.93%) and the Kuching (0.01 - 4.72%) populations was expected the occurrence of two putative species within P. lucasi. The presence of haplotypes from both populations in Haplogroup 1 and Haplogroup 2 is might be due to ability to perform high distance flight for foraging. High gene flow between these populations (Nm= -16.64) suggest the continuous distribution of P. lucasi judging from the distance of both localities. Absences of deep structure from the haplotypes tree further prove that P. lucasi has wide dispersal ability. The discrepancies of morphological and genetic data were suggested due to different evolutionary rates and the morphological features could have evolved faster than those of the mtDNA gene. However, further studies involving additional and adequate geographic representatives from the Borneo (especially from Gomantong, Madai and Mulu Caves) and Peninsular Malaysia could properly address the incongruence results of both analyses. This would also enable further verification of the hypothesis generated in this study. Keywords: P. lucasi, bats diversity, limestone protected areas of Sarawak, morphological character, population genetics, Malaysia, Borneo."
"The... more "The assessment of bats diversity from two limestone forests in protected areas of Sarawak, the Niah National Park (NP) and the Wind Cave Nature Reserve (NR) were conducted from November 2007 until April 2009. The assessments were aimed to update the current diversity of bats as well as to compile their composition with previous studies done at selected limestone areas in Sarawak. Eight to twelve mist nets and three harp traps were used, with accumulated effort of 572 trap-nights for both the Niah NP and the Wind Cave NR. A total of 1,520 individuals representing 36 species from 17 genera and 10 families were recorded. Penthetor lucasi, Hipposideros cervinus and Cynopterus brachyotis were the three most abundant species captured in both sampling areas. Meanwhile, nine species of bats are new for both localities. Seven out of nine are the new additional records added for the Niah NP, namely, Hipposideros ater, H. bicolor, H. cineraceus, Coelops robinsoni, Rhinolophus trifoliatus, Murina rozendali and Kerivoula hardwickii. While H. ridleyi and Tylonycteris robustula are new record for Wind Cave NR. Morphological analysis of 70 adult individuals of P. lucasi was done using 15 characters and 18 craniodental characters. Multiple regression and discriminant function analysis were applied to test the effects of sex, location and interaction between individuals in this study, and to determine and identify characters which were useful in differentiating individuals among populations. Most characters were significantly affected by sex (TB, D5P1L, GSL, PL, DL, C1BW and C1C1B); locality (E, TB, HF, D4P1L, D5P1L, IOW, MW and GBPL); and their interaction (E, TB, HF, D4P1L, D5P1L, GSL, IOW, MW, PL, PPL, GBPL, and C1C1B). Thus, separate analyses were done for both sexes. The D4MCL and BL of male and HF and DL of female were suggested as the best predictors for the external and craniodental characters respectively in differentiating the P. lucasi of different localities. The findings for the morphological analysis have violated the early assumption of no morphological variation between the populations of P. lucasi. It is suggested that different ecological factor such as breeding, foraging behaviour and resource availability could have influenced the morphological variation of P. lucasi populations. The population genetics of the P. lucasi was inferred using 1,061 base pairs (bp) of the Cytochrome b mitochondrial gene. A total of 77 individuals of P. lucasi were classified a priori accordingly to their localities, namely, Miri, Kuching, Sri Aman and Kelantan populations. The findings showed that the P. lucasi populations were separated into two haplogroups, namely, Haplogroup 1 (containing Miri and Kuching populations) and Haplogroup 2 (the mixture of Miri, Kuching, Sri Aman and Kelantan populations). This separation was supported with high bootstrap values in all four methods of analysis (100% in neighbour joining; 100% in maximum parsimony; 94.9% in maximum likelihood and 100% in Bayesian). The occurrence of two haplogroup was address to unclear status of P. lucasi. High genetic divergence detected between the two haplogroups (3.88%) and separation between the haplogroups is predicted as the ancient events. The historical event includes the multiple colonisation and refugia during ice age period likely the main factors led to such separation. High divergence within the Miri (0.01 - 4.93%) and the Kuching (0.01 - 4.72%) populations was expected the occurrence of two putative species within P. lucasi. The presence of haplotypes from both populations in Haplogroup 1 and Haplogroup 2 is might be due to ability to perform high distance flight for foraging. High gene flow between these populations (Nm= -16.64) suggest the continuous distribution of P. lucasi judging from the distance of both localities. Absences of deep structure from the haplotypes tree further prove that P. lucasi has wide dispersal ability. The discrepancies of morphological and genetic data were suggested due to different evolutionary rates and the morphological features could have evolved faster than those of the mtDNA gene. However, further studies involving additional and adequate geographic representatives from the Borneo (especially from Gomantong, Madai and Mulu Caves) and Peninsular Malaysia could properly address the incongruence results of both analyses. This would also enable further verification of the hypothesis generated in this study. Keywords: P. lucasi, bats diversity, limestone protected areas of Sarawak, morphological character, population genetics, Malaysia, Borneo."
Biodiversitas Journal of Biological Diversity
Genetic identification of captive orangutans is of paramount importance in providing a correct id... more Genetic identification of captive orangutans is of paramount importance in providing a correct identity that is essential for captive management. Thus, the utility of nuclear DNA sequences was tested in this study to identify the genetic identity of captive orangutans at Bukit Merah Orang Utan Island. Out of 24 DNA samples that were successfully extracted, only 10 orangutan samples were successfully sequenced for the von Willebrand factor (vWF) gene. From the results, this gene was able to separate the genus Pongo at the species level. Distance and character analyses indicated that a clear separation between P. pygmaeus and P. abelii at the species level. However, the degree of separation at species level was indicated in tree topology with moderate bootstrap values. At the subspecies level of P. pygmaeus, this gene was unable to show a clear separation between three Bornean subspecies. All the subspecies were formed clade together with each other. The vMF gene is a good nuclear gene for the study of phylogenetic relationships of orangutans in captivity at the species level, but the genetic identification at subspecies level in the genus level remains unclear. We suggest that future studies should involve multiple independent nuclear markers to increase the probability of getting reliable results.
Biodiversitas, 2019
Population census and age category character of Stump-tailed macaque, Macaca arctoides, in Northe... more Population census and age category character of Stump-tailed macaque, Macaca arctoides, in Northern Peninsular Malaysia. Biodiversitas 20: 2446-2452. Macaca arctoides is reported to be distributed only in the northern part of Malay Peninsula. Intensive scientific observations have never been carried out before on this neglected macaque in the northern range. Thus, in this article, an estimation of population data on the Malaysian stump-tailed macaques that were found in Wang Kelian forest areas in Perlis State Park, Malaysia is presented. Intensive field observations were conducted from Sept 2018 to January 2019 with scanning sampling. The study revealed a total of 171-176 stump-tailed macaques, consisting of 44 (25%) adult males, 28 (16%) adult females, 19-22 (11%) sub-adult males, 16-19 (10%) sub-adult females, 43 (25%) juveniles, and 21-23 (13%) infants. Two main groups were observed, which were the Nomad and the Batat groups. Their ranging areas appear to sometimes overlap each other, while some Nomad members were observed in the Batat group. The age structure can be differentiated through body size and pelage coloration. The stump-tailed macaque populations in Wang Kelian are sensitive to human presence, while their habitat area is threatened by human illegal poaching activities. More conservation efforts are needed to conserve this neglected macaque from local extinction.
A roost survey of cave-dwelling bats in Wind Cave Nature Reserve (Wind Cave NR) was conducted for... more A roost survey of cave-dwelling bats in Wind Cave Nature Reserve (Wind Cave NR) was conducted for 11 days from July 2013 until April 2014. This study aims to explore roosting ecology of bats in Wind Cave NR. From the total of 462 observations, five families of bats were recorded comprising 11 species of bats. These species include Penthetor lucasi, Megaderma spasma, Myotis horsfieldii, Rhinolophus affinis, R. borneensis, Hipposideros ater, H. cervinus, H. coxi, H. diadema, H. galeritus and H. larvatus. Penthetor lucasi was the most abundant species observed with colony size >100 individuals. Whereas the most roost observations was set by M. horsfieldii with 136 observations and the most diverse family was set by Hipposideridae with six species. Chi square analyses using contingency table showed statistically significant association existed between roost behaviour and the bats assemblages (p<0.05). Another key finding in this study is the discovery of a colony of H. coxi, a Bornean endemic species that serve as the first ever record for this species inside a cave and for Wind Cave NR. Overall information presented herein able to assist the local management in developing strategy for conservation, long-term species monitoring and beneficial in ecotourism purposes.
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Books by Mohd Ridwan Abd Rahman
Papers by Mohd Ridwan Abd Rahman