title: Resolving Drivers of Microbial Community Structure in The Dry Valleys of Antarctica

authors: Bottos, Eric

subjects: Antarctica

abstract: Understanding the processes that underlie patterns of microbial distribution is fundamental to the field of microbial ecology, but extremely challenging given the complexity of natural systems. Antarctica’s ice-free regions possess unique ecosystems of simple trophic structure, shaped by the harsh environmental conditions that typify the continent. The Dry Valleys comprise the largest of these regions and have one of the simplest food webs on the planet, making them a tractable system to comprehensively define relationships that influence microbial distributions at the landscape scale. The New Zealand Terrestrial Antarctic Biocomplexity Survey (nzTABS) was aimed at identifying factors that control, and can predict, biological distributions in the Dry Valleys. As part of nzTABS, the goal of the research presented in this thesis was to elucidate the factors that influence bacterial community structure in Dry Valley soils.  

This study explored how topographic, physicochemical, and spatial variation influence bacterial diversity and community structure across a Dry Valley landscape. Bacterial communities were characterized in 471 soil samples using automated ribosomal intergenic spacer analysis (ARISA). Diversity and community composition were most strongly related to variation in physicochemical soil properties, though significant relationships with topographic and spatial variables were also observed. This identified, for the first time, the influence of environmental variables on bacterial diversity and community composition across the landscape, and presents a structural equation model identifying those relationships.

The phylogenetic diversity of bacterial communities in Dry Valley soils was also examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze bacterial communities in 177 soil samples. This work identified significant relationships between the relative abundances of bacterial taxa and both abiotic and biotic variables, though these relationships explained only a small amount of community variation collectively. The relative abundances of several bacterial taxa were, however, significantly coupled to one another, suggesting that interactions between bacterial taxa may influence community compositions.

Lastly, the bacterial composition of aerosols above the Dry Valleys was examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze two aerosol samples collected in the Miers Valley, and their compositions were compared to those of previously characterized aerosols and soils from across the continent. Bacteria present in the aerosols were found to be distinct from those of local soils; instead, aerosol compositions were more similar to those of air samples reported from elsewhere on the planet. Importantly, these findings suggest that local redistribution of Dry Valley soil bacteria through atmospheric processes may be largely restricted to periods when high winds mobilize soil particles and associated biota.

This study provides novel insights into the microbial ecology of the Dry Valleys. Despite the relative simplicity of the ecosystem, the factors that influence bacterial distributions within the Dry Valleys appear to be highly complex, and include a combination of abiotic and biotic drivers. Continued research will help to disentangle relationships that influence microbial community compositions in Antarctica’s ice-free ecosystems, and will improve understanding of processes that influence microbial community assembly globally.

text: Resolving Drivers of Microbial Community Structure in The Dry Valleys of Antarctica Understanding the processes that underlie patterns of microbial distribution is fundamental to the field of microbial ecology, but extremely challenging given the complexity of natural systems. Antarctica’s ice-free regions possess unique ecosystems of simple trophic structure, shaped by the harsh environmental conditions that typify the continent. The Dry Valleys comprise the largest of these regions and have one of the simplest food webs on the planet, making them a tractable system to comprehensively define relationships that influence microbial distributions at the landscape scale. The New Zealand Terrestrial Antarctic Biocomplexity Survey (nzTABS) was aimed at identifying factors that control, and can predict, biological distributions in the Dry Valleys. As part of nzTABS, the goal of the research presented in this thesis was to elucidate the factors that influence bacterial community structure in Dry Valley soils.  

This study explored how topographic, physicochemical, and spatial variation influence bacterial diversity and community structure across a Dry Valley landscape. Bacterial communities were characterized in 471 soil samples using automated ribosomal intergenic spacer analysis (ARISA). Diversity and community composition were most strongly related to variation in physicochemical soil properties, though significant relationships with topographic and spatial variables were also observed. This identified, for the first time, the influence of environmental variables on bacterial diversity and community composition across the landscape, and presents a structural equation model identifying those relationships.

The phylogenetic diversity of bacterial communities in Dry Valley soils was also examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze bacterial communities in 177 soil samples. This work identified significant relationships between the relative abundances of bacterial taxa and both abiotic and biotic variables, though these relationships explained only a small amount of community variation collectively. The relative abundances of several bacterial taxa were, however, significantly coupled to one another, suggesting that interactions between bacterial taxa may influence community compositions.

Lastly, the bacterial composition of aerosols above the Dry Valleys was examined. High-throughput sequencing of 16S rRNA gene amplicons was used to analyze two aerosol samples collected in the Miers Valley, and their compositions were compared to those of previously characterized aerosols and soils from across the continent. Bacteria present in the aerosols were found to be distinct from those of local soils; instead, aerosol compositions were more similar to those of air samples reported from elsewhere on the planet. Importantly, these findings suggest that local redistribution of Dry Valley soil bacteria through atmospheric processes may be largely restricted to periods when high winds mobilize soil particles and associated biota.

This study provides novel insights into the microbial ecology of the Dry Valleys. Despite the relative simplicity of the ecosystem, the factors that influence bacterial distributions within the Dry Valleys appear to be highly complex, and include a combination of abiotic and biotic drivers. Continued research will help to disentangle relationships that influence microbial community compositions in Antarctica’s ice-free ecosystems, and will improve understanding of processes that influence microbial community assembly globally.

year: 2014

title: An Evaluation of the Cognitive Functioning of Individuals on Methadone Maintenance Treatment and its Relation to Treatment Adherence

authors: Yates, Susan J

subjects: methadone maintenance treatment

abstract: This research assessed the cognitive functioning of several different drug and alcohol samples, with a specific focus on individuals in methadone maintenance treatment. Additionally, this research assessed the relation between cognitive functioning and adherence to treatment in these populations. This is a link that has been suggested by research in this area previously. The present research consisted of five experiments. Experiment 1 assessed the application, within New Zealand, of the normative data for a number of psychometric tests with a non- substance using sample of New Zealand university students. The results from this study showed that the scores for the university sample were generally similar to the normative means, suggesting that the existing normative data could be used in New Zealand. Experiment 2 assessed the cognitive functioning of university students who reported regular use of alcohol and/or cannabis. The results from this study showed that the frequency of alcohol use was positively correlated with problem solving ability, while frequency of cannabis use was positively correlated with memory functioning. Cannabis use was also associated with poorer problem solving ability. These findings showed that casual use of alcohol and/or cannabis was associated with poorer functioning on some psychometric tests, and that these tests were sensitive to the effects of substance use. Experiment 3 assessed the cognitive functioning of a sample of individuals in methadone maintenance treatment in relation to their adherence to treatment. The results from this study showed deficits in memory, divided attention and cognitive flexibility, and poor mathematical ability when compared to the normative data. Treatment adherence was found to be associated with lower levels of treatment satisfaction, and findings also suggested a possible relation between poor treatment adherence and better scores on the psychometric test scores. Due to difficulties in recruiting participants, Experiment 4 assessed the cognitive functioning of a second sample of individuals in methadone maintenance in relation to treatment adherence. This sample completed a reduced battery of psychometric tests, and results showed deficits in memory, attention, and problem solving abilities compared to the normative data. Treatment adherence was not found to be associated with lower levels of treatment satisfaction in this sample. A possible relation between poor treatment adherence and better psychometric test scores was identified for this sample also, although the relation was between different test scores than those in Experiment 3. To assess whether the obtained results for Experiment 3 and Experiment 4 were specific to methadone, Experiment 5 assessed the cognitive functioning of several different drug and alcohol samples in relation to treatment adherence. The study examined the cognitive functioning of alcohol, drug and alcohol, and other opiate users, and showed that all samples had difficulty recalling information in a visual format, that a large percentage showed impairments in divided attention and cognitive flexibility, and that the drug and alcohol, and other opiate samples had deficits in problem solving ability. Treatment adherence in this study was assessed for the alcohol sample, with results showing a relation between poor treatment adherence and verbal memory ability, and divided attention and cognitive flexibility. Overall, the cognitive deficits found in the samples for each experiment were not related to treatment adherence as measured in this research. However, results for the alcohol sample suggested that there may be a link between poor adherence and impairments in verbal memory and divided attention. The findings from this research suggest that cognitive deficits and treatment adherence are not related, but this finding may be the result of limitations in this research (i.e., recruitment difficulties, adherence measures used). The clinical and research implications of the results of the research are discussed. In particular, recommendations for treatment services dealing with the drug and alcohol population are provided.

text: An Evaluation of the Cognitive Functioning of Individuals on Methadone Maintenance Treatment and its Relation to Treatment Adherence This research assessed the cognitive functioning of several different drug and alcohol samples, with a specific focus on individuals in methadone maintenance treatment. Additionally, this research assessed the relation between cognitive functioning and adherence to treatment in these populations. This is a link that has been suggested by research in this area previously. The present research consisted of five experiments. Experiment 1 assessed the application, within New Zealand, of the normative data for a number of psychometric tests with a non- substance using sample of New Zealand university students. The results from this study showed that the scores for the university sample were generally similar to the normative means, suggesting that the existing normative data could be used in New Zealand. Experiment 2 assessed the cognitive functioning of university students who reported regular use of alcohol and/or cannabis. The results from this study showed that the frequency of alcohol use was positively correlated with problem solving ability, while frequency of cannabis use was positively correlated with memory functioning. Cannabis use was also associated with poorer problem solving ability. These findings showed that casual use of alcohol and/or cannabis was associated with poorer functioning on some psychometric tests, and that these tests were sensitive to the effects of substance use. Experiment 3 assessed the cognitive functioning of a sample of individuals in methadone maintenance treatment in relation to their adherence to treatment. The results from this study showed deficits in memory, divided attention and cognitive flexibility, and poor mathematical ability when compared to the normative data. Treatment adherence was found to be associated with lower levels of treatment satisfaction, and findings also suggested a possible relation between poor treatment adherence and better scores on the psychometric test scores. Due to difficulties in recruiting participants, Experiment 4 assessed the cognitive functioning of a second sample of individuals in methadone maintenance in relation to treatment adherence. This sample completed a reduced battery of psychometric tests, and results showed deficits in memory, attention, and problem solving abilities compared to the normative data. Treatment adherence was not found to be associated with lower levels of treatment satisfaction in this sample. A possible relation between poor treatment adherence and better psychometric test scores was identified for this sample also, although the relation was between different test scores than those in Experiment 3. To assess whether the obtained results for Experiment 3 and Experiment 4 were specific to methadone, Experiment 5 assessed the cognitive functioning of several different drug and alcohol samples in relation to treatment adherence. The study examined the cognitive functioning of alcohol, drug and alcohol, and other opiate users, and showed that all samples had difficulty recalling information in a visual format, that a large percentage showed impairments in divided attention and cognitive flexibility, and that the drug and alcohol, and other opiate samples had deficits in problem solving ability. Treatment adherence in this study was assessed for the alcohol sample, with results showing a relation between poor treatment adherence and verbal memory ability, and divided attention and cognitive flexibility. Overall, the cognitive deficits found in the samples for each experiment were not related to treatment adherence as measured in this research. However, results for the alcohol sample suggested that there may be a link between poor adherence and impairments in verbal memory and divided attention. The findings from this research suggest that cognitive deficits and treatment adherence are not related, but this finding may be the result of limitations in this research (i.e., recruitment difficulties, adherence measures used). The clinical and research implications of the results of the research are discussed. In particular, recommendations for treatment services dealing with the drug and alcohol population are provided.

year: 2009

title: Māori women’s perspectives of leadership and wellbeing

authors: Ruru, Stacey Mariu

subjects: Māori women leadership

abstract: This research sought to understand how Māori women leaders maintain their wellbeing within their leadership roles. Semi-structured interviews acknowledging kaupapa Māori theory (Māori philosophy, framework) principles were used to gather the leadership journeys of five Māori women leaders from academic and business backgrounds across the North Island, New Zealand. Kaupapa Māori principles such as kānohi kitea (greeting, meeting face to face), ako Māori (learning, teaching, reciprocity, cultural pedagogy) and manāki ki te tangata (caring, hosting people) provided a methodological framework to follow during interviews with Māori women leaders. From the interviews, thematic analysis was undertaken and patterns, similarities and differences were uncovered that led to the identification of eight main themes: Humility, collective work, the influence of others, overcoming boundaries, balance between te taha hinengaro (mental or psychological wellbeing) and te taha tinana (physical wellbeing), fostering pathways, quieting the mind, and whānau (family) connections. Secondary analysis further developed and explored the themes using indigenous whakataukī Māori (Māori proverbs), which became the overarching theme and connected the eight themes to the five whakataukī. The study found that balance between te taha hinengaro (the psychological, mental wellbeing dimension) and te taha tinana (the physical dimension) from Te Whare Tapa Whā (the four corners of a house) and Te Wheke (the octopus) Māori wellbeing models supported Māori women leaders’ waiora (health, wellbeing). Central to the success of these Māori women leaders was being connected to whānau and friends, and being influenced by tāmariki (children), tauira (students) and employees. These social connections made Māori women leaders strong and resilient to change and challenges. Māori leadership practices and values such as hūmarie (humility), mana wahine (Māori women’s leadership style), manākitanga (caring) and aroha (compassion, love) contributed to leadership drivers that enhanced Māori women within their leadership roles. Finally, recommendations include enhancing practices such as those that encourage mana (influence, power, and identity), mātauranga Māori (Māori knowledge) and ako Māori for future generations to follow.

text: Māori women’s perspectives of leadership and wellbeing This research sought to understand how Māori women leaders maintain their wellbeing within their leadership roles. Semi-structured interviews acknowledging kaupapa Māori theory (Māori philosophy, framework) principles were used to gather the leadership journeys of five Māori women leaders from academic and business backgrounds across the North Island, New Zealand. Kaupapa Māori principles such as kānohi kitea (greeting, meeting face to face), ako Māori (learning, teaching, reciprocity, cultural pedagogy) and manāki ki te tangata (caring, hosting people) provided a methodological framework to follow during interviews with Māori women leaders. From the interviews, thematic analysis was undertaken and patterns, similarities and differences were uncovered that led to the identification of eight main themes: Humility, collective work, the influence of others, overcoming boundaries, balance between te taha hinengaro (mental or psychological wellbeing) and te taha tinana (physical wellbeing), fostering pathways, quieting the mind, and whānau (family) connections. Secondary analysis further developed and explored the themes using indigenous whakataukī Māori (Māori proverbs), which became the overarching theme and connected the eight themes to the five whakataukī. The study found that balance between te taha hinengaro (the psychological, mental wellbeing dimension) and te taha tinana (the physical dimension) from Te Whare Tapa Whā (the four corners of a house) and Te Wheke (the octopus) Māori wellbeing models supported Māori women leaders’ waiora (health, wellbeing). Central to the success of these Māori women leaders was being connected to whānau and friends, and being influenced by tāmariki (children), tauira (students) and employees. These social connections made Māori women leaders strong and resilient to change and challenges. Māori leadership practices and values such as hūmarie (humility), mana wahine (Māori women’s leadership style), manākitanga (caring) and aroha (compassion, love) contributed to leadership drivers that enhanced Māori women within their leadership roles. Finally, recommendations include enhancing practices such as those that encourage mana (influence, power, and identity), mātauranga Māori (Māori knowledge) and ako Māori for future generations to follow.

year: 2016