INFLUENCE OF CLIMATE CHANGE ON THE SPATIOTEMPORAL DISTRIBUTION PATTERNS OF CROCIDURA SPP. IN THE SUNDALAND

• Main Author: Yudha Samawi, Maha
• Format: Final Project
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/75091
• Institution: Institut Teknologi Bandung

Climate change and global warming are the fastest causes of extinction, i.e. through shifting and even reducing the distribution of organisms' habitats. Unfortunately, information related to its impact on animal distribution patterns, especially in Sundaland is still limited. For this reason, this study aims to identify the influence of climate change on the spatiotemporal distribution patterns of animals in Sundaland, in particular on Crocidura (Wagler, 1832), which is an ideal model organisms for biogeographic inference. Distribution modeling of Crocidura spp. in general was carried out using maximum entropy approach (MaxEnt 3.4.4) with inputs covering the occurrence points of sixteen species of Crocidura spp. in Sundaland, bioclimatic factors, elevation, and land cover; in accordance with the software specifications and characteristics of the organisms used. The inferences were conducted for three general periods: (1) contemporary; (2) after the Last Glacial Maximum (LGM) to Mid-Holocene); and (3) projected years 2060, 2080 and 2100 under Shared Socioeconomic Pathway (SSP) climatic scenarios 1-2.6 (minimum impact), SSP2-4.5 (medium impact), and SSP5-8.5 (maximum impact). The model was then evaluated in two stages, which are: (1) by applying a threshold value of 0.75 for the Area Under ROC (Receiver Operating Characteristic curve) curve [AUC]; followed by (2) ground checks. The second stage was conducted through the installation of 55 Shearman, Victor, and pitfall traps for three days in each area selected based on the result of the previous evalution step. The AUC results ranged from 0.838-0.999 (good to excellent). For the majority of species, the most influential environmental variable was "elevation", except for Crocidura vosmaeri and C. hutanis which were more influenced by "mean diurnal range". Based on this, the ground check was conducted in three areas representing elevation differences (Mount Papandayan, Mount Sawal, and Leuweung Sancang), resulting in eleven specimens from four species were obtained with the number of Crocidura specimens decreasing as elevation decreased. Based on past modeling, it was suspected that Sundaland Crocidura spp. entered from mainland Asia through the lowlands of the Malay Peninsula which then spread to insular areas during the formation of savanna land bridges, followed by allopatric and/or sympatric speciations. In general, the dynamics of past distribution patterns were inconsistent with the hypothesized impacts of climate and sea level rise, except for C. vosmaeri, which was isolated in insular areas of the Pleistocene Epoch, lived at low elevations, was less adaptive to temperature changes and prefered savanna as its habitat. Similar trends were seen in future modeling results that were also sensitive to species characteristics, which could then be categorized into scenarios: (1) extinction; (2) habitat fluctuation; and (3) population increase followed by a constant rate. In general, greater changes were seen for high-impact scenarios (SSP2-4.5 and SSP5-8.5). This study suggests that the "climate" (change) is not the primary determinant in shaping the spatiotemporal distribution patterns of Crocidura spp. in Sundaland. However, it is still important to mitigate the impacts of climate change as climatic factors still possess significant factors on its fitness , especially when interacting with intrinsic and extrinsic biological factors of the organism.