title: The role of thermal tolerance in biological invasion

authors: Wilde, Margot

abstract: Biological invasion and climate change are among the greatest threats to biodiversity currently. Several factors influence what makes a successful invasive species. Among these is the thermal tolerance of the invasive species. An organism’s thermal physiology underpins many aspects of its life, including the habitats in which it can survive, its reproduction and its development. Climate change is increasing global average temperatures at an unprecedented pace, which is increasing thermal stress on virtually all life around the world. These effects are particularly pronounced in ectotherms, which are reliant on environmental temperature to set their body temperature and drive their metabolism. Insects comprise a significant proportion of globally important invasive species. As well as being ectothermic, they have a complex life cycle with a number of developmental stages, all of which may be influenced by environmental temperatures. Invasive species can often tolerate or adapt to a broad range of environmental conditions. They may therefore be expected to have a broader thermal tolerance than their native counterparts, and than other invasives that have a narrower invaded range.  

This research used a blowfly model to investigate how thermal tolerance differed across temperatures, using a static temperature assay to measure thermal knockdown time. Key foci included the effects of both developmental heat acclimation and adult heat tolerance on thermal performance.  In Chapter 2, variation in adult heat tolerance was assessed across three temperatures (41℃, 42℃, 43℃) in five blowfly species invasive to New Zealand. I found that the two more globally invasive species in the study exhibited higher heat tolerance than the three less invasive Calliphora species, whose native ranges are generally more temperate. In Chapter 3, the effect of developmental temperature on adult knockdown time in a single species (Calliphora stygia) was assessed. I showed that C. stygia reared at the lowest temperature (18℃) had the highest knockdown time and the smallest body size, while those reared at 26℃ 1 exhibited  the shortest knockdown time and an intermediate body size, with those reared at 22℃ being the largest.   

Collectively, my results indicate that adult heat tolerance varies between invasive blowfly species, but that developmental acclimation temperature may not have a significant effect on adult heat tolerance. Given the increasing global temperatures seen with climate change, the effects of invasive species are likely to increase, with some species likely to do better than others in a warming world. Thermal performance will undoubtedly play a role in filtering out the ‘winners’ and ‘losers’, therefore further research into both heat and cold tolerance in both laboratory and field settings are crucial.

text: The role of thermal tolerance in biological invasion Biological invasion and climate change are among the greatest threats to biodiversity currently. Several factors influence what makes a successful invasive species. Among these is the thermal tolerance of the invasive species. An organism’s thermal physiology underpins many aspects of its life, including the habitats in which it can survive, its reproduction and its development. Climate change is increasing global average temperatures at an unprecedented pace, which is increasing thermal stress on virtually all life around the world. These effects are particularly pronounced in ectotherms, which are reliant on environmental temperature to set their body temperature and drive their metabolism. Insects comprise a significant proportion of globally important invasive species. As well as being ectothermic, they have a complex life cycle with a number of developmental stages, all of which may be influenced by environmental temperatures. Invasive species can often tolerate or adapt to a broad range of environmental conditions. They may therefore be expected to have a broader thermal tolerance than their native counterparts, and than other invasives that have a narrower invaded range.  

This research used a blowfly model to investigate how thermal tolerance differed across temperatures, using a static temperature assay to measure thermal knockdown time. Key foci included the effects of both developmental heat acclimation and adult heat tolerance on thermal performance.  In Chapter 2, variation in adult heat tolerance was assessed across three temperatures (41℃, 42℃, 43℃) in five blowfly species invasive to New Zealand. I found that the two more globally invasive species in the study exhibited higher heat tolerance than the three less invasive Calliphora species, whose native ranges are generally more temperate. In Chapter 3, the effect of developmental temperature on adult knockdown time in a single species (Calliphora stygia) was assessed. I showed that C. stygia reared at the lowest temperature (18℃) had the highest knockdown time and the smallest body size, while those reared at 26℃ 1 exhibited  the shortest knockdown time and an intermediate body size, with those reared at 22℃ being the largest.   

Collectively, my results indicate that adult heat tolerance varies between invasive blowfly species, but that developmental acclimation temperature may not have a significant effect on adult heat tolerance. Given the increasing global temperatures seen with climate change, the effects of invasive species are likely to increase, with some species likely to do better than others in a warming world. Thermal performance will undoubtedly play a role in filtering out the ‘winners’ and ‘losers’, therefore further research into both heat and cold tolerance in both laboratory and field settings are crucial.

year: 2025

title: Progger 3: A low-overhead, tamper-proof provenance system

authors: Corrick, Tristan James Carlile

subjects: Progger

abstract: Data provenance, which describes how data is accessed and used since the time it is created, is a valuable resource with a wide range of uses. It can be used simply to know who has accessed one's data, or be used in more complex scenarios such as detecting malware. One method for collecting data provenance is to observe system calls. This thesis presents Progger 3, a system that observes system calls on Linux in order to collect data provenance. There are several existing provenance systems that observe system calls, but they have limitations regarding security, efficiency, and usability. Progger 3 remedies many of these limitations. As a result, Progger 3 is a working implementation of a provenance system that can observe any system call, guarantee tamper-proof provenance collection as long as the kernel on the client is not compromised, and transfer the provenance to other systems with confidentiality and integrity, all with a relatively low performance overhead.

text: Progger 3: A low-overhead, tamper-proof provenance system Data provenance, which describes how data is accessed and used since the time it is created, is a valuable resource with a wide range of uses. It can be used simply to know who has accessed one's data, or be used in more complex scenarios such as detecting malware. One method for collecting data provenance is to observe system calls. This thesis presents Progger 3, a system that observes system calls on Linux in order to collect data provenance. There are several existing provenance systems that observe system calls, but they have limitations regarding security, efficiency, and usability. Progger 3 remedies many of these limitations. As a result, Progger 3 is a working implementation of a provenance system that can observe any system call, guarantee tamper-proof provenance collection as long as the kernel on the client is not compromised, and transfer the provenance to other systems with confidentiality and integrity, all with a relatively low performance overhead.

year: 2021

title: Whānau aspirations, extracurricular activity  and positive youth development:  The leisure activity patterns and narratives of successful young Māori men and how they might inform  urban whānau raising tamatāne.

authors: Clarke, Gloria Hinemoa

subjects: Leisure

abstract: The purpose of this research is to offer parents and whānau (extended family groups) insight about the kinds of leisure activities that might make a positive contribution to their boys’ development. Focused on the positive developmental benefits of leisure participation in relation to Māori boys, and employing a kaupapa Māori framework and qualitative methods, this study represents a foray into new territory. 
	Conducted ‘by, with, and for’ Māori (the indigenous people of Aotearoa New Zealand), and guided by the question ‘How might the leisure activity patterns and narratives of successful young Māori men inform urban whānau raising tamatāne (Māori boys/sons)?’ the three-phase research design was strengths-based, collaborative, and both retrospective and prospective. In phase one, a group of 11 parents participated in focus group hui (gatherings) in which they established the criteria for ‘successful young Māori men’ (SYMM) based on their aspirations for their primary-school aged boys. In phase two, this whānau of interest then selected six SYMM from a pool of eight volunteers, who, along with one or both of their parents participated in one-off semi-structured interviews. In these interviews, we co-constructed life and leisure maps, and discussed how their childhood leisure activities and experiences contributed to their development and who they are today. In phase three, a selection of raw data from these interviews was prepared for a group analysis, during which the whānau of interest made three key observations: (1) As children and youth, these SYMM had participated in a number and range of organised and informal leisure activities including sport, kapa haka (Māori cultural performance), music, art, and for three of them, faith-based activities; (2) they were “connected” to their parent(s) and whānau; and (3) their leisure activities had brought them into contact with positive male role models. Consequently, the whānau of interest talked about increasing the number and variety of their boys’ leisure activities; how they could further support their boys’ leisure participation; and bringing more male role models into their boys’ lives. 
	The findings of this study support the current literature regarding extracurricular activity participation in relation to positive youth development, but also highlight some methodological issues and cultural and contextual nuances. The research supports international and local studies in which high-performing students participated in a number and combination of extracurricular activities. In contrast, however, the experiences and reflections of the SYMM in this study highlight the limitations of combining all sports and all arts into broad activity categories. The research participants’ leisure activities also point to the relevance and applicability of the Te Whare Tapa Whā model of health and wellbeing. Their involvement in kapa haka contrasts with the (North American) literature in which males are a minority in the performing arts, and while some studies indicate that participation in music making declines in high school, these young men began playing musical instruments in high school. Moreover, the salience and significance of the research participants’ casual leisure activities challenges the tendency to cast informal leisure as the antithesis of extracurricular activity participation. These findings raise questions about the applicability of using international activity categories in Aotearoa New Zealand research, and consequently the need to conduct our own leisure and positive youth development studies. 
Other topics raised in this thesis include rugby and masculinity, spirituality, and the tensions involved in building and honouring our children’s rangatiratanga (independence). The short answer to the research question is that a variety and balance of leisure activities has the potential to make positive contributions to boys’ lives. Implications, limitations, and recommendations for future research are also discussed.

text: Whānau aspirations, extracurricular activity  and positive youth development:  The leisure activity patterns and narratives of successful young Māori men and how they might inform  urban whānau raising tamatāne. The purpose of this research is to offer parents and whānau (extended family groups) insight about the kinds of leisure activities that might make a positive contribution to their boys’ development. Focused on the positive developmental benefits of leisure participation in relation to Māori boys, and employing a kaupapa Māori framework and qualitative methods, this study represents a foray into new territory. 
	Conducted ‘by, with, and for’ Māori (the indigenous people of Aotearoa New Zealand), and guided by the question ‘How might the leisure activity patterns and narratives of successful young Māori men inform urban whānau raising tamatāne (Māori boys/sons)?’ the three-phase research design was strengths-based, collaborative, and both retrospective and prospective. In phase one, a group of 11 parents participated in focus group hui (gatherings) in which they established the criteria for ‘successful young Māori men’ (SYMM) based on their aspirations for their primary-school aged boys. In phase two, this whānau of interest then selected six SYMM from a pool of eight volunteers, who, along with one or both of their parents participated in one-off semi-structured interviews. In these interviews, we co-constructed life and leisure maps, and discussed how their childhood leisure activities and experiences contributed to their development and who they are today. In phase three, a selection of raw data from these interviews was prepared for a group analysis, during which the whānau of interest made three key observations: (1) As children and youth, these SYMM had participated in a number and range of organised and informal leisure activities including sport, kapa haka (Māori cultural performance), music, art, and for three of them, faith-based activities; (2) they were “connected” to their parent(s) and whānau; and (3) their leisure activities had brought them into contact with positive male role models. Consequently, the whānau of interest talked about increasing the number and variety of their boys’ leisure activities; how they could further support their boys’ leisure participation; and bringing more male role models into their boys’ lives. 
	The findings of this study support the current literature regarding extracurricular activity participation in relation to positive youth development, but also highlight some methodological issues and cultural and contextual nuances. The research supports international and local studies in which high-performing students participated in a number and combination of extracurricular activities. In contrast, however, the experiences and reflections of the SYMM in this study highlight the limitations of combining all sports and all arts into broad activity categories. The research participants’ leisure activities also point to the relevance and applicability of the Te Whare Tapa Whā model of health and wellbeing. Their involvement in kapa haka contrasts with the (North American) literature in which males are a minority in the performing arts, and while some studies indicate that participation in music making declines in high school, these young men began playing musical instruments in high school. Moreover, the salience and significance of the research participants’ casual leisure activities challenges the tendency to cast informal leisure as the antithesis of extracurricular activity participation. These findings raise questions about the applicability of using international activity categories in Aotearoa New Zealand research, and consequently the need to conduct our own leisure and positive youth development studies. 
Other topics raised in this thesis include rugby and masculinity, spirituality, and the tensions involved in building and honouring our children’s rangatiratanga (independence). The short answer to the research question is that a variety and balance of leisure activities has the potential to make positive contributions to boys’ lives. Implications, limitations, and recommendations for future research are also discussed.

year: 2020