Judul: Variasi dan Distribusi Tikus Besar Sulawesi (Paruromys dominator) Berdasarkan Pendekatan Morfologi
Abstrak: Correlations between natural geographic boundaries and variations in organisms' morphology have been well-documented in Sulawesi Island, which has unique geological history and hundreds of endemic species. One of the widely distributed species of small mammals is Sulawesi giant rat (Paruromys dominator). Paruromys dominator can be found in all forests in Sulawesi from the north to the south, also ranging from lowland forests with an altitude of 50 meters above sea level to mountain forests with more than 2000 meters above sea level. With Sulawesi's diverse geographical conditions and unique geological history, P.dominator can be an appropriate model for studying the relationship between geographical conditions and morphological variations of a species. Furthermore, a comprehensive study on this species has also never been conducted. Previous studies on P. dominator showed no variation in its skull morphology. However, the study only used 11 samples from 3 locations. Here, we measure 19 skull characteristics for 131 adult complete-skull specimens from six distribution areas in Sulawesi. We investigate the variation in skull characteristics using agglomeration nesting (AGNES) for cluster analysis and the standardized major axis (SMA) for allometry analysis. Our results show that the samples can be categorized into two groups, but those are not influenced by distribution areas, elevation, or sex. Paruromys dominators in group 1 had a larger skull size than group 2. The two groups can be distinguished from four characteristics: breadth of mesopterygoid fossa, breadth of first upper molar, length of the auditory bulla, and breadth of incisive foramina. The four characteristics have different allometric patterns. Variations on two characteristics (breadth of mesopterygoid fossa and breadth of first upper molar) are related to mastication. These characteristics are relatively smaller in Group 1 than in Group 2. In Group 2, the larger size of the mesopterygoid fossa and first upper molar compensates for the small size of its skull, making it capable of chewing large foods or hard foods. The other two characteristics (length of auditory bulla and breadth of incisive foramina) relate to the communication process. Variations in auditory bulla led to variations in the ability between groups to detect predators through hearing. Then the variation in the breadth of incisive foramina is closely related to the vomeronasal organ (VNO), which has the main function of recognizing partner pheromones in mating behavior, alarm pheromones of mutual species and kairomone from a predator in antipredator behavior. We propose that the skull variation of this species is not correlated with geography because of the good locomotion of the rats, which supports them to cope with various geographical conditions. The variation is, in fact, more clearly correlated with their feeding habits, mating behaviour, and ability to escape predation., Hubungan antara batas geografis alami dan variasi morfologi organisme telah didokumentasikan dengan baik di Pulau Sulawesi. Sulawesi dikenal memiliki sejarah geologis yang unik dan ratusan spesies endemik. Salah satu spesies mamalia kecil endemik yang tersebar luas di Sulawesi adalah Tikus Besar Sulawesi (Paruromys dominator). Paruromys dominator dapat ditemukan di seluruh hutan di Sulawesi mulai dari bagian utara hingga selatan, juga mulai dari hutan dataran rendah dengan ketinggian 50
Keyword: Morphology, Paruromys dominator, Sulawesi, Variation, Skull