Landscape genetics and habitat viability of the estuarine crocodile (Crocodylus porosus) in Sabah: Conservation management of an apex predator

Kntayya, Sai Kerisha 2024. Landscape genetics and habitat viability of the estuarine crocodile (Crocodylus porosus) in Sabah: Conservation management of an apex predator. PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF (PhD thesis) - Accepted Post-Print Version Download (9MB) | Preview
	PDF (Cardiff University Electronic Publication Form) - Supplemental Material Restricted to Repository staff only Download (2MB)

Abstract

The estuarine crocodile (Crocodylus porosus), an apex predator and an integral component of Sabah’s biodiversity, faces increasing pressures from habitat loss, human-wildlife conflict, and environmental changes. This thesis provides a comprehensive study of C. porosus populations in Sabah, integrating demographic, genetic, spatial, and viability analyses to inform effective conservation strategies. Surveys conducted across 10 rivers revealed variability in population densities and size-class distributions, with fragmentation limiting genetic flow among populations. Spatial movement analyses, using GPS telemetry, highlighted sex-specific differences in home range patterns, the importance of oxbow lakes and tributaries as critical habitats, and potential avoidance of anthropogenic structures such as bridges. Genetic analysis of 100 tissue samples using 16S, CytB, ND2 and D-loop markers revealed that while the overall genetic diversity of C. porosus in Sabah remains high, individual river populations exhibited low diversity, with the Paitan River identified as a genetic hotspot. Population Viability Analysis (PVA) simulations using Vortex projected that the overall metapopulation could persist over the next century, but this is heavily dependent on the Kinabatangan River population. Many smaller river populations, including those in Padas and Labuk, showed alarming trends toward decline or local extinction, emphasizing the need for targeted conservation efforts. The findings stress the importance of habitat restoration, enhancing connectivity, and managing human-crocodile conflict to support population recovery and sustainability. Additionally, the thesis highlights the need for non-lethal strategies to mitigate conflict and the development of wildlife-friendly infrastructure to reduce habitat fragmentation. By synthesizing insights across ecological, genetic, and spatial scales, this research provides a robust framework for understanding and managing C. porosus populations in Sabah. The results underline the critical role of habitat quality, genetic diversity, and ecological connectivity in ensuring the long-term viability of this species. This thesis offers actionable recommendations for conservation, aiming to preserve C. porosus as a vital component of Sabah’s unique biodiversity and a key contributor to the ecological balance of its riverine ecosystems.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	7 March 2025
Last Modified:	07 Mar 2025 16:45
URI:	https://orca.cardiff.ac.uk/id/eprint/176727

Actions (repository staff only)

Edit Item