Thesis Defense at CES on 11 January 2023 at 11:00 am titled "Space-use patterns in predator-prey systems" by Vibhuti Shastri from IISc, Bengaluru.

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Topic: 
Space-use patterns in predator-prey systems
Speaker: 
Vibhuti Shastri, IISc, Bengaluru.
Date & Time: 
11 Jan 2023 - 11:00am
Event Type: 
Thesis Defense
Venue: 
Online
Abstract:

 

Patterns of space use are key in understanding predator-prey interactions. The spatial overlap of predators with their prey influences their encounter rates, predation rates, and ultimately predator-prey dynamics. Animals engage in a dynamic behavioral response race, where prey actively try to avoid predators while predators seek out prey-rich spaces. Many extant studies fail to test for the emergent outcome of the dynamic space-use response race because they either fail to test for the dynamic responses of predator and prey when both are mobile or not addressing the underlying fine-scale behavioral mechanisms that drive space use in mobile predators and prey. In a qualitative literature survey, I examined how many studies report spatial and or temporal correlations between the distributions of mobile predator and prey and identified external constraints or ‘anchors’ that may influence the observed distributions. Anchors are defined as constraints like fixed resources or the presence of refuges that restrict free access to patches of choice. If only prey are constrained, predators can win the behavioral response race by achieving a positive spatial overlap with the prey, whereas a negative correlation may be seen if predators are constrained. Our results show that the presence of the identified anchors significantly influence the reported outcomes of the predator-prey space-use patterns. Such anchors can become important predictors of the emergent space-use patterns in predator-prey systems, making their identification vital in studies of predator-prey population dynamics and applied ecology. I then studied how predators from the African savanna choose home ranges based on the seasonal and yearly scales and how these timescales affect their choice of kill hotspots. I used movement data for tagged leopards and African wild dogs from the Karongwe Game Reserve in South Africa for this analysis. Our results show that the seasons affect where animals choose to hunt within their home range and that the choice of the home range itself may also change over seasons and years. There was also a difference in the space-use of leopards and wild dogs as expected from the differences in their behavioral mechanisms and hunting strategies. Overall, from movement data analysis, we conclude that a positive spatial overlap alone may not translate to uniform predation risk in the landscape as there are certain hotspots with higher encounters and predation activity that are riskier for prey. Future studies should focus on environmental constraints, intrinsic factors, and fine scale behavioral responses to explicate predation risk and ultimately its effect on predator-prey dynamics in a system.

Click here to join the online defense.