Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Filters

Settings

Subject: search.filters.subject.Predation (Biology)

Search Results

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Experimental evolution under predation in P. fluorescens SBW25 : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Microbiology & Genetics at Massey University, Auckland, New Zealand
    (Massey University, 2022) Sadeghpour Golzar, Farhad
    Predator-prey interactions are recognised to change the pace of evolution in microbial communities, but investigations into how selection for predation accelerates antagonistic behaviours, genomic evolution and the process of coadaptation are scarce. Here we performed a 20-day and an extended 90-day evolution experiment to investigate the adaptive traits that arise in prey bacterium Pseudomonas fluorescens SBW25 on solid media in the presence and absence of a wild Acanthamoeba sp. Coevolution led to bacterial diversity, resistance to predation in coevolved bacterial lineages and evolution of predators. We show evidence of reciprocal adaptation, strong phenotypic and genotypic parallelism among prey lineages undergoing predation. We observed evolution of new colony morphotypes such as Wrinkly Spreader, Volcano and Mountain. Evolved morphotypes conferred grazing resistance and an increase in relative prey fitness that resulted in increased encystment and reduced replication of the protozoan populations. Mutation profiles of the coevolved phenotypes were associated with altered gene function in amrZ, wspF, fadD1, fadD2 and putative hypothetical protein upstream of RND transporter. RNA sequencing results of the mutants also revealed a significant increase in the number of genes that up or downregulated while interacting with Acanthamoeba sp. We investigated the degree to which these mutations affect biofilm formation, capsulation, motility, mucoid and fatty acid degradation pathways. Some of these traits are associated with virulence in pathogenic organisms. We further found evidence of mutualisms where both prey and predator increased their survival relative to their respective ancestors. On the other side, we show promoted killing performance and higher generations upon feeding on WT bacteria in coevolved Acanthamoeba compared to their ancestors. Together, our findings demonstrate the emergence of divergent colony morphologies and molecular parallelism that arise as an adaptation to predation and notably affects the fitness and evolution of predators suggesting Red Queen co-evolutionary dynamics between predators and prey. These findings suggest that protozoan predation can profoundly influence the course of genetic and phenotypic evolution in short and long-time scales.
  • Thumbnail Image
    Item
    Predator-prey interactions in subtropical forest and ecology and conservation of swamp deer or barasingha (Rucervus duvaucelii duvaucelii) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Auckland, New Zealand
    (Massey University, 2021) Yadav, Hemanta Kumar
    The tiger, an apex predator, is an indicator of a healthy ecosystem. Therefore, the conservation of this immensely important umbrella species necessitates ecological knowledge on its interaction with co-predators and status of significant prey species sharing the habitat. Royal Bengal tiger (Panthera tigris tigris) and common leopard (Panthera pardus fusca) are two sympatric carnivores in suitable habitats of the Indian subcontinent where sympatric ungulates cervids are prevailing as major prey species. This thesis investigated the diet overlap of these sympatric apex predators and the population status of prey species in the subtropical lowland landscape popularly known as Terai Arc Landscape (TAL), Nepal. This thesis further explored ranging behaviour, habitat preference, movements, conservation genetics and food habits of the swamp deer or barasingha (Rucervus duvaucelii duvaucelii), the largest cervid prey species of tiger in the western portion of TAL, Nepal. The line transect survey revealed high density and biomass of major cervid prey species compared to other tiger bearing protected areas, with large-sized swamp deer, medium-sized spotted deer (Axis axis) and hog deer (Axis porcinus) being main prey species. Scat analysis revealed that wild ungulates were the main food of both predators. Large-sized wild preys (mainly swamp deer) were found more frequently in tiger scats, and domestic cattle were found more frequently in leopard scats. Both predators consumed the medium-sized spotted deer in high proportions resulting in a high diet overlap. Swamp deer played a critical role in diet partition between the two cats. Dominant tigers displaced leopards to the degraded fringe habitat where the latter subsisted on the domestic livestock, a major cause of human-wildlife conflict. The monitoring of nine radio-collared swamp deer showed a high 95% Minimum Convex Polygon (MCP) and 95% Fixed Kernel (FK) home ranges compared to other sympatric ungulates such as spotted deer, hog deer, and barking deer (Muntiacus muntjac). There was no significant variation in 95% FK annual home ranges between sexes and across three seasons. Overall, the grassland was the most preferred habitat of swamp deer in all the seasons, and the dense Sal (Shorea robusta) forest was the least preferred. In the monsoon season, the moderately dense Sal forest followed the grassland. Within grassland, swamp deer preferred Imperata cylindrica assemblage followed by Imperata cylindrica – Narenga porphyrocoma and Narenga porphyrocoma assemblage. A range shift from the grassland to the Sal (Shorea robusta) forest, only during the monsoon season, indicated that the grassland had reached the carrying capacity during this season. The radio-collared swamp deer crossed the international border. During the rutting season, they consistently used contiguous habitat patches of Lagga-Bagga area of Pilibhit Tiger Reserve, India, thus emphasising the need for transboundary cooperation to conserve this species. The genetic variability, population structure and effective population size of Shuklaphanta National Park (SNP) and Bardia National Park (BNP) populations of swamp deer were examined using the mitochondrial (mt) DNA and microsatellite markers. The analysis revealed moderate to high genetic diversity compared to other swamp deer populations in India. Neutrality tests, which are used to evaluate demographic effects, did not support population expansion. The multimodal pattern of mismatch distribution indicated that both swamp deer populations are under demographic equilibrium. Furthermore, population bottleneck analysis indicated no signature of a bottleneck for both populations. Bayesian cluster analysis and population differentiation test revealed two population clusters with low population differentiation. The effective population size in BNP was below 50, which is often regarded as a threshold below which inbreeding depression is likely to occur. It is recommended to design and implement an effective conservation strategy to enhance the genetic diversity and increase the population size of swamp deer in BNP through an in-situ conservation program and translocation of some breeding individuals from SNP to BNP. Faecal microhistological analysis of swamp deer, sympatric hog deer, and spotted deer from both grassland and the Sal forest habitats revealed that graminoids constituted the majority of the diet of these species in both habitats. However, the proportion of woody plants in diets of spotted deer was significantly higher than the other two. Apart from the graminoids, woody plant Shorea robusta and herb Phoenix humilis were major plant species consumed in the Sal forest. Among graminoid species, early successional tall grasses, especially Saccharum spontaneum, were the dominant food of all three deer species in both habitats. The importance of early successional tall grasses in their diet emphasised the key role of the threatened alluvial floodplains in conserving threatened mammal species in South Asia. Swamp deer foraged more in late succession tall grasses (Saccharum narenga and Themeda spp.) and short grasses (Imperata cylindrica, Cyperus spp., Chrysopogon zizanioides, Cymbopogon spp.) than hog deer and spotted deer. Despite the similarity of their diet, the three ungulates coexisted through differential consumption of plants species and seasonal habitat partitioning.
  • Thumbnail Image
    Item
    Parallel simulation methods for large-scale agent-based predator-prey systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Computer Science at Massey University, Albany, New Zealand
    (Massey University, 2019) Quach, Dara (Minh) Quang
    The Animat is an agent-based artificial-life model that is suitable for gaining insight into the interactions of autonomous individuals in complex predator-prey systems and the emergent phenomena they may exhibit. Certain dynamics of the model may only be present in large systems, and a large number of agents may be required to compare with macroscopic models. Large systems can be infeasible to simulate on single-core machines due to processing time required. The model can be parallelised to improve the performance; however, reproducing the original model behaviour and retaining the performance gain is not straightforward. Parallel update strategies and data structures for multi-core CPU and graphical processing units (GPUs) are developed to simulate a typical predator-prey Animat model with improved perfor- mance while reproducing the behaviour of the original model. An analysis is presented of the model to identify dependencies and conditions the parallel update strategy must satisfy to retain original model behaviour. The parallel update strategy for multi-core CPUs is constructed using a spatial domain decomposition approach and supporting data structure. The GPU implementation is developed with a new update strategy that consists of an iterative conflict resolution method and priority number system to simultaneously update many agents with thousands of GPU cores. This update method is supported by a compressed sparse data structure developed to allow for efficient memory transactions. The performance of the Animat simulation is improved with parallelism and without a change in model behaviour. The simulation usability is considered, and an internal agent definition system using a CUDA device Lambda feature is developed to improve the ease of configuring agents without significant changes to the program and loss of performance.
  • Thumbnail Image
    Item
    Predator-prey dynamics : a review : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Mathematics at Massey University
    (Massey University, 1981) Johnstone, David Gordon
    With the recent publication explosion in population ecology, there is an increasing need for a review of the diverse approaches towards modelling. This thesis is concerned with modelling of two-species predator-prey ecosystems using two-dimensional dynamic systems of first-order differential equations. Chapters one and two are introductory in nature, discussing the place of theoretical models in ecology, and the development of the classical Lotka-Volterra model and its subsequent fall from favour. Chapter three looks at general aspects of predator-prey modelling. Graphical and analytical approaches are outlined in detail, as is the more recent curvature approach. Further results are obtained when growth and predation factors are considered separately, viewed as components to the model equations. Recent work on the consequences of enrichment, harvesting, stocking and natural selection are also dealt with. In chapter four, more specific predator-prey models are presented. Other, more variable qualities of predator-prey ecosystems are also considered, such as age structure and predation responses in chapter four; and time delays, spatial heterogeneity and migration in chapter five. Chapter six is a mathematical digression from the main body of the review. An analytical result for dynamic systems with a centre is proven, in an attempt to support an alternative outlook on the relationship between predator-prey ecosystems and their representative models. Finally, chapter seven briefly discusses potential applications in the future, the most promising being aspects of harvesting and control theory in resource management systems.
  • Thumbnail Image
    Item
    Predator-prey interactions between mosquitofish (Gambusia affinis holbrooki) and whistling frog (Litoria ewingi) tadpoles : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2001) Tol, Renske van
    Aspects of the impact of newly introduced predatory mosquitofish (Gambusia affinis holbrooki) on the resident introduced whistling frog (Litoria ewingi) were examined by means of experiments. Microhabitat preferences of whistling frog tadpoles and mosquitofish were investigated through a series of laboratory trials and the behaviour of both species during attacks by mosquitofish on tadpoles was also recorded. Microhabitat use of these species will overlap in natural situations, but both species changed their microhabitat use with age. In the presence of plants, small tadpoles moved towards the surface, while larger tadpoles prefered to associate with the substrate. The same pattern occurred when an alga chip (food source) was placed on the substrate. Small female mosquitofish were more attracted to plants than larger mosquitofish, and less attracted to tadpoles (potential prey). The extensive recent literature on predation is reviewed with emphasis on existing works on predator-prey interactions involving amphibian larvae. Behaviour of both species during attacks changed with age. Small tadpoles were more likely than large tadpoles to flee from an attack. Larger female mosquitofish were more likely to attack moving tadpoles (in comparison with small female mosquitofish), and to attack the body of tadpoles (as opposed to the tail). There was no difference between the behaviour of small female and male mosquitofish. Most attacks were non-fatal. Inactive prey were more likely to be attacked in this combination of predator and prey, which is in direct contrast with previous studies. When a plant with complex three-dimensional architecture was added attacks still occurred, but overall the frequency of attacks was lower, indicating that the presence of sufficient refuge may lessen the effect of mosquitofish introductions on whistling frog tadpole populations. A field experiment was also conducted but results were not conclusive. L. ewingi may become reduced to breeding in ephemeral waters if G. a. holbrooki invades permanent waters successfully and removes L. ewingi extensively.
  • Thumbnail Image
    Item
    The effect of predator presence on the behaviour of sheep in pain : a thesis presented in partial fulfilment of the requirements for the degree of Masterate in Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2006) Young, Suzanne Karen
    In the veterinary and ecology literature two claims regarding predator-prey interactions are frequently made. Firstly, that vertebrate predators typically capture disadvantaged individuals, including the young, weak, sick, aged and injured, from prey populations in higher than expected proportions. Secondly, as a consequence of this, prey animals when injured or diseased, are said to attempt to behave in a normal manner, similar to that of a healthy conspecific, so as not to draw the attention of a predator. This thesis investigates whether the presence of a predator modifies the behaviour of sheep and lambs that are in pain. There are two parts to this thesis. Part one examines the behaviour of lambs following castration. Part two examines the behaviour of adult sheep in response to a mechanical pressure device. The aim of part one was to monitor the restlessness behaviour of lambs following castration in the presence of four stimuli (a goat, a dog, a cardboard box, and a tape recorder playing the sound of a dog barking), and the effect that the lambs' dam has on this behaviour. Three hundred and eighty four lambs were observed in this study, half of these lambs were castrated and the other half were left as controls. Castrated lambs exhibited more restlessness behaviour than control lambs (p<0.0001). However, restlessness behaviour was not different between lambs exposed to one of the four stimuli. The presence of the lambs' dam significantly reduced the restlessness behaviours of both castrated (p<0.0003) and control lambs (p<0.0019). The aim of part two was to determine the threshold response of 16 adult Romney ewes in response to a painful mechanical pressure device in the presence of four stimuli (a dog, a goat, a tape recording of a drum beat and a tape recording of a dog barking). The response threshold was higher in sheep exposed to the dog than to the goat (p<0.05). The significant difference between the behaviour of castrated and control lambs suggests that castration is a painful procedure. Moreover, lambs may rely on their mother to cue them on how to behave, as lambs significantly reduced the amount of restlessness behaviour they exhibited when their ewe was present (castrated lambs p<0.0003; control lambs p<0.0019). Adult sheep find dogs aversive, and their pain thresholds were higher in their presence than when a goat was present. This suggests that sheep are able to alter their behaviour in the presence of a potential threat. These results justify further research into the behaviour of prey animals in the presence of a predator. Two key avenues for future research include; determining how prey animals view humans, and further investigating the mother-young relationship and the affect the presence of a predator has on this.