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Genomic insights into the evolution of the parasitoid Microctonus aethiopoides
(The University of Waikato, 2026) Hussain, Meeran; McGaughran, Angela; Parvizi, Elahe; McNeill, Mark; Dearden, Peter
Parasitoids are used as biocontrol agents in classical biological control programmes for controlling invasive pest populations. In Aotearoa New Zealand, there are two strains of Microctonus aethiopoides that have been used against two serious pest weevils of the Sitona group. However, there is limited understanding of M. aethiopoides adaptability, particularly in the area of reproductive mode and host associations. My thesis explores these gaps, using population and comparative genomic approaches to investigate the adaptability of M. aethiopoides. Chapter 2 is a review that synthesises global research on parasitoid adaptation and identifies knowledge gaps across four key traits i.e., reproductive mode, olfaction, thermal tolerance, and microbiomes. Using the three Microctonus species in New Zealand as a focal example, this chapters explains why these traits matter for biocontrol and how genomic technologies reveal their underlying molecular mechanisms. Chapter 3 explores the adaptation of Irish asexual M. aethiopoides in New Zealand by analysing whole-genome resequencing data from 43 individuals representing historic (Ireland) and contemporary populations. The study reveals two distinct genetic clusters, most likely reflecting the genetic ancestry of introduced populations rather than post-introduction geographic isolation. All populations exhibit very low diversity and limited population expansion since release, consistent with their asexual nature and suggesting limited adaptation. Asexual M. aethiopoides show some heterozygosity across populations, supporting automictic thelytoky, likely via central fusion, as the primary reproductive mechanism. However, linkage disequilibrium patterns resemble those of sexual organisms, raising the possibility of facultative sex. This chapter sheds light on the adaptation, spread, and reproductive strategies of asexual M. aethiopoides in New Zealand. Chapter 4 further examines parasitoid adaptation, with a focus on host-associated divergence. Using eight newly assembled genomes from M. aethiopoides strains collected from three different hosts (Hypera postica, Sitona discoideus, S. obsoletus) and geographically distinct regions, this study investigates how host use and geography shape genomic structure. Comparative genomics reveals a clear host-associated phylogenetic split, with the H. postica lineage distinct from Sitona-associated lineages. Heterozygosity patterns support this separation, showing highest diversity in the H. postica group. However, gene families are mostly conserved across strains, with transposable element-related genes showing rapid evolution, suggesting their active role in genome restructuring. Chemosensory genes are also largely conserved, with only modest variation in odourant receptors that may reflect host-associated differences, although fragmentation and annotation bias cannot be ruled out. Overall, host association appears to be a key driver of divergence in M. aethiopoides, largely shaped by genome-level variation rather than major shifts in host-specific gene families. Finally, Chapter 5 assembles and characterises the first complete mitochondrial genome of M. aethiopoides, generated using a hybrid Oxford Nanopore-Illumina assembly. This study uncovers a long circular (33,173 bp) mitogenome with a unique gene arrangement, contributing a valuable genetic resource for future studies of mitochondrial evolution in parasitoids. Overall, my thesis demonstrates how genomic technologies can be used to provide a more comprehensive understanding of the evolutionary factors shaping a species’ genome and population structure. It provides a valuable genomic resource and sets a foundation of resources for continuing to build understanding of adaptation in the context of asexuality and host association in M. aethiopoides.
Temperature dependence of plant photosynthesis and respiration using the Macromolecular Rate Theory (MMRT)
(The University of Waikato, 2026-03-12) Darwin Leonel, Moreno Echeverry; Margaret , Barbour; Vic, Arcus; Louis, Schipper; Miko, Kirschbaum; Lìyǐn, Liáng
This thesis quantifies the temperature dependence of key traits that determine leaf carbon balance in C3 plants, using Sunflower as a model system, with emphasis on the photorespiratory CO2 compensation point (Γ*), the rate of CO2 release in the light (DL), the maximal carboxylation capacity (Vcmax), the maximal electron transport capacity (Jmax), and the components of dark respiration (Rdark). The central objective was to identify temperature dependence models for each trait that were both parsimonious and physiologically interpretable. The research combined controlled leaf gas exchange across wide ranges of temperature and CO2 with comparative model fitting. I evaluated constant-Q10 relationships, simple and peaked Arrhenius formulations, and macro molecular rate theory (MMRT), with and without an explicit high temperature deactivation term. Γ* increased approximately exponentially across the measurement range from 4 to 42 °C, and a constant-Q10 model best captured this behaviour. The temperature dependence of DL was well represented by MMRT. For the photosynthetic capacities, I used an MMRT formulation that used inflection-point temperature (Tinf) as parameters and included explicit deactivation terms. That approach captured the curvature at cool to moderate temperatures and the decline at supra-optimal temperatures, with Jmax exhibiting a cooler inflection and a cooler optimum than Vcmax. For Rdark and its components, an MMRT anchored at the observed inflection temperature and fitted without a deactivation term captured the smooth warm side curvature expected from progressive changes in mitochondrial coupling and accelerated substrate use with increasing temperature. This thesis provides a unified framework for selecting temperature dependence models for leaf gas exchange traits. It introduces DL as the light linked composite flux of CO2 release, rather than a proxy of dark respiration alone, and it presents a published ii refinement for estimating Γ* and DL using the Laisk method based on gas-exchange measurements at low light and low intercellular CO2 concentrations. The refined methodology explicitly used photosynthetic theory in our parameter estimation and reduced systematic bias in estimating Γ* and DL. These advances improve the parameterisation of photosynthesis models and strengthens the transfer to crop and land- surface modelling under variable thermal environments. The thesis is organised in seven chapters. Chapter 3 has been published, and when it is cited elsewhere in the thesis it is referenced as Moreno-Echeverry et al., 2026. Chapter 1. General introduction. It sets the global climate and carbon cycle context, frames leaf carbon balance as the net outcome of photosynthesis and respiration, and explains why accurate parameterisation of Γ*, DL, Vcmax and Jmax matters for models. It defines temperature as a primary driver of gas-exchange rates, outlines the limit of Arrhenius and constant-Q10 functions, introduces MMRT as a thermodynamic alternative, and states the thesis aims. Chapter 2. Background. It reviews photosynthesis and respiration at the leaf scale, outlines gas exchange principles, describes the FvCB model and presents methods used to estimate Γ* and DL. It summarises temperature response models, including the constant- Q10 function, two variants of the Arrhenius equation and MMRT. The chapter also identifies the knowledge gaps that motivate the specific work described in the thesis. Chapter 3. Estimating Γ* and DL using the Laisk method combined with photosynthetic theory. It examines the classical Laisk approach, identifies sources of bias arising from linearisation of inherently curvilinear Anet-Cc responses, and formalises estimation of Γ* and DL within the FvCB framework. It uses simulations and leaf gas exchange measurements to test performance and uncertainty of the modified approach and compares it with the performance and uncertainty of the original Laisk approach. This chapter is based on the published methodological study. iii Chapter 4. Temperature dependence of Γ* and DL. It quantifies how Γ* and DL vary with temperature over the range from 4 to 42 °C. It compares the constant-Q10, simple and peaked Arrhenius, and MMRT, with and without explicit high temperature deactivation term. It reports model selection, parameter estimates and presents relevant diagnostics. Chapter 5. Temperature dependence of Vcmax and Jmax. The chapter derives these parameters from Anet-Ci curves. It compares the Arrhenius formulations with MMRT, evaluates curvature, inflection and optimum temperatures, and contrast the thermal responses of carboxylation and electron transport. Chapter 6. Temperature dependence of the components of leaf CO2 release in the dark. It separates and analyses the different components of dark respiration, post illumination burst, light enhanced dark respiration and dark respiration in steady-state across temperature and integrates metabolite profiling across the light-dark transition to relate CO2 fluxes to substrate availability. It tests the Arrhenius and MMRT formulations and identifies the model that best capture warm side curvature without deactivation terms. Chapter 7. Conclusions and perspectives. It synthesises the finding across chapters, and temperature response models, discusses implications for photosynthesis and respiration modelling, and outlines priorities for future research.
A pedagogical framework for embedding computational thinking in authentic technology practice
(Japan Society of Technology Education (JSTE), 2025) Fox-Turnbull, Wendy; Wu, Shaoqun
Computational thinking is an aspect of digital technologies in the New Zealand Curriculum that teaches children to approach problems systematically, using logical and analytical reasoning. This paper presents a study undertaken in a small-town primary school in New Zealand with a high population of Māori students. The study drew on four aspects from Kotsopoulos et al.’s framework of pedagogical experiences: unplugged, tinkering, making, remixing to investigate pedagogical strategies that facilitate the successful embedding of computational thinking within authentic technological practice. The research aimed to identify learning pedagogies that support young learners in their understanding of computational thinking through designing and developing digital technologies. The qualitative methodologies were informed by the three pedagogical principles from Bishop and Berryman to guide the research design and frame learning support for students. Key themes that emerged from the data included the values of local context, self-autonomy, classroom organisation, use of physical and digital manipulatives. Finally, the paper presents a model for the pedagogical delivery of computational thinking when embedded in technological practice in primary schools, drawing from and adding to Kotsopoulos and colleague’s pedagogical framework. The most significant modification situates the existing model within authentic technology practice, providing context for learning. The model shows an adjustment from ‘Making’ to ‘Designing and Making’, thus strengthening the position of digital technologies within the Technology learning area. The model also signals that authentic technological within a primary classroom practice is heavily impacted by ‘the pragmatics of delivery’ through a range of pedagogical and organisational strategies developed to ensure the needs of all students are met and to support them through their learning journey in computational thinking. The last significant modification of Kotsopoulos and colleagues’ model is the removal of ‘remixing’ because the primary aged students in this study did not reach the level of sophistication required for remixing. The aim of the framework is to assist teachers and teacher educators to design and develop successful teaching and learning strategies for implementing computational thinking into authentic technology practice in primary schools.
Reproductive biology and spawning substrate preferences of European Perch (Perca fluviatilis) from two New Zealand lakes
(The University of Waikato, 2025-11) Whitaker-White, Hannah; Ling, Nick
European perch (Perca fluviatilis) has dominated freshwater systems in New Zealand since its introduction in 1868. This introduced species has established itself by outcompeting native species and altering the physicochemical properties of habitats. Eradication and control efforts in New Zealand seldom focus on initiating management at spawning, with little attention to their reproductive biology and plasticity. Despite many studies across the world focusing on these aspects, most are in the context of population protection within their native territories or in fisheries. Lake Rototoa and the Hamilton Lake (also known as Lake Rotoroa) are two lakes within the North Island of New Zealand that vary considerably in size and quality, and host populations of European perch that have dominated both systems. Sampling from both lakes occurred over a 12-month period, where measurements of body size, gonad development, fecundity and condition were collected to provide insight into each population’s health and reproductive biology. An artificial spawning substrate experiment over six weeks consisted of three different substrates at five sites in both lakes and in laboratory tanks to investigate the potential for spawning substrate preferences. A total of 159 perch were caught and dissected from the Hamilton Lake, and 126 were caught and dissected from Lake Rototoa. Spawning appeared to be asynchronous at Lake Rototoa from condition and GSI results, and synchronous at the Hamilton Lake. Size and condition indices were higher at the Hamilton Lake and displayed some seasonal patterns. Fecundity at the Hamilton Lake ranged from 71,202 to 80,400.96 compared to 40,844 to 73,232.21 eggs per female at Lake Rototoa during the spawning season. Oocyte diameters were slightly larger at the Hamilton Lake, with a range of 0.836 mm and 2.019 mm compared to 0.839 mm and 1.886 mm at Lake Rototoa. Perch did not use any artificial spawning substrates at all three sites. Results suggested a more stunted population at Lake Rototoa, likely due to different water qualities and resource availability. These results provide a solid foundation for control methods targeting spawning strategies in European perch. However, improved techniques for artificial spawning substrates are necessary, particularly focusing on the location and timing of where and when they are deployed.
Liberalism in 19th Century Europe: To what extent did liberalism influence the Concert of Europe?
(The University of Waikato, 2025) Heron, Quinn; Steff, Reuben
The Concert of Europe (the Concert), that lasted from 1814 to 1914, was a system of international relations that was, in many respects, illiberal. Much of the scholarship of the Concert has accepted that realist concerns, such as the balance of power, played a dominant role in shaping the Concert. It might seem strange then to ask what role liberal ideas and principles played in a system so widely regarded as realist. Yet, that is the goal of this thesis; to ask the question ‘to what extent did liberalism influence the Concert of Europe?’ Traversing the fields of History and International Relations, this thesis utilizes both disciplines, combined with qualitative analysis, to identify liberalism within Concert rhetoric and the Concert’s actors while challenging the prominence of realist explanations. The Concert displayed prominent liberal characteristics in both the rhetoric used during several crises and the actions and beliefs of the actors within it. This thesis concludes that liberal ideas and principles influenced the Concert to a significant, and often overlooked extent, and draws lessons from its operation for understanding the emerging 21st century multipolar system.