Geographical and Habitat Comparison of Selected Life History Attributes in Eutropis multifasciata (Squamata: Scincidae)

Thanisha, Kumar (2023) Geographical and Habitat Comparison of Selected Life History Attributes in Eutropis multifasciata (Squamata: Scincidae). [Transcript]

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Abstract

Eutropis multifasciata, the Common Sun Skink, is a live-bearing species of the squamate family Scincidae. It exhibits a pan-tropical distribution in Southeast Asia. Despite being a subject of frequent observation, its presence in proximity of forest edges and human settlements prompts questions regarding its life history and distribution. The primary objective of this study is to gain a comprehensive understanding of the ecological aspects associated with the species at two geographically discrete regions, one in the northern (Kledang Saiong Eco Park, Ipoh, Peninsular Malaysia) and two in the southern regions (campus of UNIMAS in Kota Samarahan and the Sebungan Oil Palm Estate near Bintulu, Sarawak, in East Malaysia). Variation in body mass across populations within the focal species was found, with individuals in the northern region exhibiting greater mass compared to those from the south. Typically observed inhabiting leaf litter, rocks and areas exposed to sunlight on the forest floor, radio transmitters help determine the location from more secretive microhabitats, such as within the trunks of oil palm trees and beneath the soil surface. These observations indicate that the species may exhibit semi-arboreal and semi-fossorial behaviour, depending on the broad habitat types utilised. A total of 11 microhabitat types were associated, of which on/under leaf litter (24.0%), and on/under/inside fallen log or dead stump (17.33%) were primary. The utilisation of microhabitats exhibits notable variation between the Perak and Sarawak sites. This variation is not attributed to latitudinal differences, but rather to distinct local habitat characteristics. Males demonstrate a broader array of microhabitat categories in contrast to females, based on the number of occupancy of microhabitats, possibly for increasing chances of encounters with females. Moreover, there are notable variations with a p-value of less than 0.001 in the microhabitat utilised by male and female focal species. The utilisation of microhabitats was anticipated by taking into consideration the significant effects of ambient and substrate temperature on the surrounding habitat using Principal component analysis (PCA) with a p-value less than 0.001. Home range size was determined using the 100% Minimum Convex Polygons method. The mean range size was 1,150.18 m2, with no significant variation between regions (p = 0.575) or sexes (p = 0.117), rather influenced by ambient temperature, body temperature and sex in the generalised model. Additionally, daily movement is influenced by body temperature and regions (northern and southern). Eutropis multifasciata exhibits thermoregulation, recorded mean body temperature being 27.9°C (± SE 0.129, range 22.7–38.3°C, n = 672), during active and sedentary periods. A noteworthy difference was the significant difference in body temperatures between the sexes in the northern (p = 0.022), but not in the southern region (p = 0.628). The relationship between substrate- and body temperature (r = 0.879) was stronger than between ambient- and body temperature (r = 0.705), supporting thigmothermy and secondary heliothermy as mechanisms of behavioural thermoconformation. The species displays a combination of active and ambush foraging strategies, depending on the local prey types. No latitudinal location of study sites correlated to variations in prey preference among populations. Diet includes known insect pests, including termites and cockroaches, these observations suggesting its role as a biocontrol agent of importance. Furthermore, the skink was documented to be the subject of predation, contributing to its position within the broader framework of the trophic web. The current study thus has yielded ecological data that has enhanced our understanding of the life history of Eutropis multifasciata across habitats. Tropical ectotherm species are currently facing threats from anthropogenic activities, particularly land clearance for agricultural purposes and global climate change. The presence of such information can be valuable for the conservation and management of this and other ectothermic species of tropical south-east Asia.

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