Sains Malaysiana 48(10)(2019): 2103–2111

http://dx.doi.org/10.17576/jsm-2019-4810-05

Morphometric Analysis of Craniodental Characters of the House Rat, Rattus rattus (Rodentia: Muridae) in Peninsular Malaysia

(Analisis Morfometri Ciri Kraniodental Tikus Rumah Rattus rattus (Rodentia: Muridae) di Semenanjung Malaysia)

NURUL HUDA MOHAMAD IKBAL¹, DHARINI PATHMANATHAN³, SUBHA BHASSU¹, KHANOM SIMARANI¹ & HASMAHZAITI OMAR^1,2*

¹Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

²Museum of Zoology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

³Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

Received: 19 April 2019/Accepted: 11 September 2019

ABSTRACT

Rattus rattus which is believed to be native to India is easily found in all continents of the world. With the absence of R. rattus from lineage I and the presence of lineage IV in Southeast Asia, little is known about how rodent morphology varies biogeographically. We evaluate the skull morphometrics in the population of R. rattus in Peninsular Malaysia and examine the intraspecific variation of the skull by assessing 20 craniodental characters of 130 R. rattus specimens. After observing the correlation matrix, highly correlated characters were removed and the remaining 14 craniodental characters were analysed using the conventional morphometrics method via univariate and multivariate statistics. We assessed the impact of age, sex and geographical factors (latitude, longitude and precipitation) on craniodental size. Male and female specimens were analysed separately since statistically significant sexual dimorphism was present. Males showed greater craniodental measurements compared to females. Three distinct age groups (C2, C3 and C4) were visible in the principal component analysis (PCA) and canonical variate analysis (CVA) plots for male and female specimens. Ages C2 and C3 shared similarities in craniodental measurements while C4 showed variability compared to C2 and C3. None of the geographical factors studied showed statistical significance for both male and female R. rattus. The results obtained from this study could potentially be a yardstick to observe if similar variations in craniodental traits are present in R. rattus from other countries in the Southeast Asian region.

Keywords: Conventional morphometrics; craniodental; geographic variation; ontogenetic; sexual dimorphism

ABSTRAK

Rattus rattus yang dipercayai berasal dari India mudah ditemui di setiap benua di dunia. Dengan ketiadaan R. rattus daripada 'lineage I' serta kehadiran R. rattus daripada 'lineage IV' di Asia Tenggara, sedikit diketahui mengenai bagaimana morfologi tikus berbeza secara biogeografi. Kami menilai morfometri tengkorak populasi R. rattus di Semenanjung Malaysia dan mengkaji variasi intraspesies bagi tengkorak dengan menilai 20 ciri-ciri kraniodental bagi 130 spesimen R. rattus. Setelah memantau matriks korelasi, ciri-ciri berkorelasi tinggi dikeluarkan dan baki 14 daripada ciri-ciri telah dipilih dan analisis dijalankan berdasarkan kaedah morfometri konvensional menggunakan statistik univariat dan multivariat. Kami mengkaji pengaruh umur, jantina dan faktor-faktor geografi (latitud, longitud dan pemendakan) terhadap saiz kraniodental. Dimorfisme seks yang signifikan secara statistik wujud, maka spesimen jantan dan betina dianalisis secara berasingan. Tikus jantan menunjukkan ukuran kraniodental yang lebih besar berbanding tikus betina. Tiga kumpulan umur yang jelas (C2, C3 dan C4) kelihatan pada plot analisis komponen prinsipal (PCA) dan plot analisis variat kanonikal (CVA) bagi kedua-dua spesimen jantan dan betina. Kumpulan umur C2 dan C3 mempunyai persamaan daripada segi ukuran kraniodental manakala C4 menunjukkan perbezaan yang ketara berbanding C2 dan C3. Kesemua faktor geografi yang dikaji tidak menunjukkan keertiaan berstatistik bagi R. rattus jantan dan betina. Hasil yang diperoleh daripada kajian ini berpotensi menjadi panduan untuk dicerap sekiranya variasi yang sama wujud pada ciri-ciri kraniodental dalam R. rattus dari negara-negara lain di rantau Asia Tenggara.

Kata kunci: Dimorfomisme seks; kraniodental; morfometri konvensional; ontogenetik; variasi geografi

REFERENCES

Abdel-Rahman, E.H., Taylor, P.J., Contrafatto, G., Lamb, J.M., Bloomer, P. & Chimimba, C. T. 2008. Geometric craniometric analysis of sexual dimorphism and ontogenetic variation: A case study based on two geographically disparate species, Aethomys ineptus from southern Africa and Arvicanthis niloticus from Sudan (Rodentia: Muridae). Mammalian Biology 74: 361-373.

Aplin, K.P., Suzuki, H., Chinen, A.A., Chesser, R.T., Ten Have, J., Donnellan, S.C., Catzeflis, F., Soubrier, J., Fang, Yin-Ping., Robins, J., Matisoo-Smith, E., Bastos, A.D.S., Maryanto, I., Sinaga, M.H., Denys, C., Van Den Bussche, R.A., Conroy, C., Rowe, K. & Cooper, A. 2011. Multiple geographic origins of commensalism and complex dispersal history of black rats. PLoS ONE 6(11): e26357.

Aplin, K.P., Chesser, T. & Have, J.T. 2003. Evolutionary biology of the genus Rattus: Profile of an archetypal rodent pest. ACIAR Monograph Series 96: 487-498.

Ben Faleh, A.R., Cornette, R., Annabi, A., Said, K. & Denys, C. 2013. Patterns of size and shape skull variability in Tunisian populations of Jaculus jaculus (Rodentia: Dipodidae). Acta Zoologica Bulgarica 65: 217-223.

Ben Faleh, A.R., Annabi, A. & Said, K. 2012. Morphometric variation in black rat Rattus rattus (Rodentia: Muridae) from Tunisia. Acta Zoologica Bulgarica 64: 381-387.

Bezerra, A.M.R. & de Oliveira, J.A. 2010. Taxonomic implications of cranial morphometric variation in the genus Clyomys Thomas, 1916 (Rodentia: Echimyidae). Journal of Mammalogy 91: 260-272.

Bohoussou, H.K., Akpatou, B.K., Kadjo, B., Soulemane, O., N’Goran, E.K. & Nicolas, V. 2014. Morphometric variation in the forest rodent Malacomys edwardsi (Rodentia: Muridae) in Côte d’Ivoire. Journal of Applied Biosciences 80: 7014-7023.

Bronson, F.H. 1989. Mammalian Reproductive Biology. Chicago, US: University of Chicago Press.

Buckle, A.P. & Smith, R.H. 2015. Rodent Pests and Their Control. Wallingford, UK: CABI Publishing.

Corbet, G.B. & Hill, J.E. 1992. The Mammals of the Indomalayan Region: A Systematic Review. New York: Oxford University Press.

Francis, C.M. 2008. A Field Guide to the Mammals of Southeast Asia. London, UK: New Holland Publishers Limited.

Kahle, D. & Wickham, H. 2013. Ggmap: Spatial visualization with ggplot2. The R Journal 5(1): 144-161.

Lalis, A., Evin, A. & Denys, C. 2009. Morphological identification of sibling species: The case of west African Mastomys (Rodentia: Muridae) in sympatry. Comptes Rendus Biologies 332: 480-488.

Martínez, J.J., Millien, V., Simone, I. & Priotto, J.W. 2014. Ecological preference between generalist and specialist rodents: spatial and environmental correlates of phenotypic variation. Biological Journal of the Linnean Society 112: 180-203.

Musser, G.G. & Carleton, M.D. 2005. Superfamily Muroidea. In Mammal Species of the World: A Taxonomic and Geographic Reference. 3rd ed., edited by Wilson, D.E. & Reeder, D.M. Baltimore: Johns Hopkins University Press.

Musser, G.G. & Newcomb, C. 1983. Malaysian murids and the giant rat of Sumatra. Bulletin of the American Museum of Natural History 174(4): 327-598.

Musser, G.G., Lunde, D.P. & Son, N.T. 2006. Description of a new genus and species of rodent (Murinae, Muridae, Rodentia) from the tower karst region of northeastern Vietnam. American Museum Novitates 3517: 1-41.

Nicolas, V., Wendelen, W., Barriere, P., Dudu, A. & Colyn, M. 2008. Morphometric variation in Hylomyscus alleni and H. stella (Rodentia: Muridae), and description of a new species. Journal of Mammalogy 89: 222-231.

Nowak, R.M. 1999. Walker’s Mammals of the World. 6th ed. Baltimore: Johns Hopkins University Press.

Richard, A.B., Allan, R.W., Ray, B., Thomas, P.M. & Alex, D. 2018. Maps: Draw Geographical Maps. R Package Version 3.3.0.

Schlager, S. 2017. Morpho and Rvcg - Shape analysis in R. In Statistical Shape and Deformation Analysis, edited by Zheng, G., Li, S. & Szekely, G. London, UK: Academic Press.

Venables, W.N. & Ripley, B.D. 2002. Modern Applied Statistics. 4th ed. New York: Springer-Verlag.

Ventura, J. & Lopez-Fuster, M.J. 2000. Morphometric analysis of the black rat, Rattus rattus, from Congreso Island (Chafarinas Archipelago, Spain). Orsis 15: 91-102.

Wilson, D.E. & Reeder, D.M. 2005. Mammal Species of the World: A Taxonomic and Geographic Reference. 3rd ed. Baltimore: Johns Hopkins University Press.

Woodruff, D.S. & Turner, L.M. 2009. The Indochinese-Sundaic zoogeographic transition: A description and analysis of terrestrial mammal species distributions. Journal of Biogeography 36(5): 803-821.

Yusof, F.M., Md Ismail, A.I.B. & Ali, N.M. 2010. Modeling population harvesting of rodents for the control of Hantavirus infection. Sains Malaysiana 39(6): 935-940.

Zainal Abidin, A.H. & Noor Azmi, A. 1999. Infection of Trypanosoma lewisi in wild rats. Sains Malaysiana 28: 1-8.

*Corresponding author; email: zaiti_1978@um.edu.my