title: Paleoenvironmental Variability during the Middle Miocene Climatic Optimum Reconstructed using a Lake Sediment Record from the Otago Region, New Zealand

authors: Garrity, Francis David Alain

subjects: Miocene

abstract: Climate archives indicate that the varied interaction of several cycles across a range of timescales exerted a prevailing control on climate throughout the Holocene and Pleistocene. However, due to the scarcity of highly resolved lacustrine records, it has so far been difficult to recognize sub-Milankovitch scale cycles in earlier epochs. Climate variability during the Middle Miocene was particularly extensive, and included the Miocene Climatic Optimum, representing the maximum temperatures experienced during the Cenozoic. A high resolution account of Southern Hemisphere paleoenvironmental variability during the Miocene Climatic Optimum has never previously been produced and is thus of significant importance.
The Hindon Maar diatomite is a laminated lacustrine deposit dominated by Aulacoseira Spp. diatoms. This lake formed due to a phreatomagmatic eruption as part of the Waipiata volcanic field, and accumulated during the Langhian Age (~15.2 Ma; Middle Miocene) in the Otago region of New Zealand. A high-resolution multi-proxy analysis was conducted on a 10.8-m-long core of this annually resolved lake sediment, which varve thicknesses suggest represents 7600 years of deposition. Gamma density, magnetic susceptibility, CIELAB L*a*b* colour, particle size, compositional data and petrographic images were collected. Compositional data included biogenic silica, total organic carbon and schist, determined using Fourier transform infrared spectroscopy.
Principal components analysis of these variables enabled the identification of underlying processes which I interpret to represent precipitation, wind speed and temperature. Aulacoseira Spp. diatoms are highly sensitive to variations in wind speed, and thus most changes in lake productivity reflect wind strength changes relating to underlying cyclicity. In addition, electrofacies analysis is used to identify six reoccurring and persisting paleoenvironmental states. Based on electrofacies analysis of principal component factor scores, a high resolution reconstruction is proposed and related to the underlying cyclical factors.
It is suggested that wind strength on this time scale during the Middle Miocene may partially respond to the interaction of two solar cycles and one orbital cycle. These are the DeVries cycle (200 years), the Hallstatt cycle (2300 years) and precession (~26000 years). These cycles and others were identified using a combination of sum of sinusoidal signal analysis, Tukey-Hamming spectral analysis and wavelet transformations. Peaks in these cycles thus likely generated warm conditions, causing prevailing westerly winds to move northwards and intensify, whilst troughs correspond to a decline in oceanic temperatures and wind speeds. This investigation therefore demonstrates the influence of sub-Milankovitch scale cycles and solar forcing on conditions during the Miocene Climatic Optimum for the first time in the Southern Hemisphere.

text: Paleoenvironmental Variability during the Middle Miocene Climatic Optimum Reconstructed using a Lake Sediment Record from the Otago Region, New Zealand Climate archives indicate that the varied interaction of several cycles across a range of timescales exerted a prevailing control on climate throughout the Holocene and Pleistocene. However, due to the scarcity of highly resolved lacustrine records, it has so far been difficult to recognize sub-Milankovitch scale cycles in earlier epochs. Climate variability during the Middle Miocene was particularly extensive, and included the Miocene Climatic Optimum, representing the maximum temperatures experienced during the Cenozoic. A high resolution account of Southern Hemisphere paleoenvironmental variability during the Miocene Climatic Optimum has never previously been produced and is thus of significant importance.
The Hindon Maar diatomite is a laminated lacustrine deposit dominated by Aulacoseira Spp. diatoms. This lake formed due to a phreatomagmatic eruption as part of the Waipiata volcanic field, and accumulated during the Langhian Age (~15.2 Ma; Middle Miocene) in the Otago region of New Zealand. A high-resolution multi-proxy analysis was conducted on a 10.8-m-long core of this annually resolved lake sediment, which varve thicknesses suggest represents 7600 years of deposition. Gamma density, magnetic susceptibility, CIELAB L*a*b* colour, particle size, compositional data and petrographic images were collected. Compositional data included biogenic silica, total organic carbon and schist, determined using Fourier transform infrared spectroscopy.
Principal components analysis of these variables enabled the identification of underlying processes which I interpret to represent precipitation, wind speed and temperature. Aulacoseira Spp. diatoms are highly sensitive to variations in wind speed, and thus most changes in lake productivity reflect wind strength changes relating to underlying cyclicity. In addition, electrofacies analysis is used to identify six reoccurring and persisting paleoenvironmental states. Based on electrofacies analysis of principal component factor scores, a high resolution reconstruction is proposed and related to the underlying cyclical factors.
It is suggested that wind strength on this time scale during the Middle Miocene may partially respond to the interaction of two solar cycles and one orbital cycle. These are the DeVries cycle (200 years), the Hallstatt cycle (2300 years) and precession (~26000 years). These cycles and others were identified using a combination of sum of sinusoidal signal analysis, Tukey-Hamming spectral analysis and wavelet transformations. Peaks in these cycles thus likely generated warm conditions, causing prevailing westerly winds to move northwards and intensify, whilst troughs correspond to a decline in oceanic temperatures and wind speeds. This investigation therefore demonstrates the influence of sub-Milankovitch scale cycles and solar forcing on conditions during the Miocene Climatic Optimum for the first time in the Southern Hemisphere.

year: 2017

title: The effect of population density on mating dynamics and the interaction between pre- and post-copulatory selection in the New Zealand giraffe weevil

authors: Lambert, Michaela

subjects: Ecology

abstract: Sexual selection is thought to be the main driver for the evolution of pre-copulatory traits (e.g., weapons and ornaments) used to gain access to mates, and post-copulatory traits (e.g., sperm form and function) used to maximize fertilisation success. Individuals that have a greater ability to acquire resources from their environment may be able to invest in both types of traits equally, and therefore may have a competitive advantage during mate acquisition and sperm competition. For males that are competitively inferior, they may choose to invest more into one type of trait, resulting in a trade-off between the investment in one trait over another.  The New Zealand giraffe weevil, Lasiorhynchus barbicornis, provides an ideal study system to explore size-dependent investment in sexual traits. Males show extreme size variability, leading to differences in mating success between males of different body sizes. Large males are better at acquiring mates and winning fights and as a result, small males have adopted a sneaking tactic to avoid pre-copulatory competition with larger rivals. Therefore, small males may choose to invest more into their post-copulatory traits. Further, giraffe weevils form large aggregations on host trees during the summer months, making them an ideal subject to explore how demographic factors can influence the mating success of males. In giraffe weevils, how body size and population density interact to influence mating success is not well understood. In this study, I used an experimental behavioural assay and morphometrics to investigate how males of different body sizes may be investing into their pre- and post-copulatory traits to engage or avoid sperm competition.  I found that small males may be investing more into post-copulatory traits than large males. However, I found no evidence of a phenotypic trade-off between pre- and post-copulatory traits. I also used an observational dataset collected from a natural population to explore how population density, among other demographic factors, interact with body size to influence male mating success. I found that male giraffe weevils have density-dependent mating success, with small males doing best at high densities, and large males at low densities. My research will contribute to a growing body of work looking at how sexual selection can shape the life-history traits of insects.

text: The effect of population density on mating dynamics and the interaction between pre- and post-copulatory selection in the New Zealand giraffe weevil Sexual selection is thought to be the main driver for the evolution of pre-copulatory traits (e.g., weapons and ornaments) used to gain access to mates, and post-copulatory traits (e.g., sperm form and function) used to maximize fertilisation success. Individuals that have a greater ability to acquire resources from their environment may be able to invest in both types of traits equally, and therefore may have a competitive advantage during mate acquisition and sperm competition. For males that are competitively inferior, they may choose to invest more into one type of trait, resulting in a trade-off between the investment in one trait over another.  The New Zealand giraffe weevil, Lasiorhynchus barbicornis, provides an ideal study system to explore size-dependent investment in sexual traits. Males show extreme size variability, leading to differences in mating success between males of different body sizes. Large males are better at acquiring mates and winning fights and as a result, small males have adopted a sneaking tactic to avoid pre-copulatory competition with larger rivals. Therefore, small males may choose to invest more into their post-copulatory traits. Further, giraffe weevils form large aggregations on host trees during the summer months, making them an ideal subject to explore how demographic factors can influence the mating success of males. In giraffe weevils, how body size and population density interact to influence mating success is not well understood. In this study, I used an experimental behavioural assay and morphometrics to investigate how males of different body sizes may be investing into their pre- and post-copulatory traits to engage or avoid sperm competition.  I found that small males may be investing more into post-copulatory traits than large males. However, I found no evidence of a phenotypic trade-off between pre- and post-copulatory traits. I also used an observational dataset collected from a natural population to explore how population density, among other demographic factors, interact with body size to influence male mating success. I found that male giraffe weevils have density-dependent mating success, with small males doing best at high densities, and large males at low densities. My research will contribute to a growing body of work looking at how sexual selection can shape the life-history traits of insects.

year: 2021

title: A case study of using the He Pikinga Waiora Implementation Framework: Challenges and successes in implementing a twelve-week lifestyle intervention to reduce weight in Māori men at risk of diabetes, cardiovascular disease and obesity

authors: Oetzel, John G.

subjects: Science & Technology

abstract: BACKGROUND: Māori men have stark health inequities around non-communicable diseases. This study describes the case of a partnership attempting to develop and implement a culturally centred intervention through a collaborative partnership to potentially address the inequities. In particular, the partnership followed a participatory, co-design approach using the He Pikinga Waiora (HPW) Implementation Framework; the study presents lessons learnt in addressing health inequities following this framework. METHODS: The partnership involved a university research team and a Māori community health provider. They engaged with other stakeholders and several cohorts of Māori men through a co-design process to adapt a 12-week lifestyle intervention. The co-design process was documented through meeting notes and interviews with partners. Two cohorts participated in separate single group pre-intervention/post-intervention designs with multi-method data collection. Key outcome measures included weight loss, self-reported health, physical activity, and nutrition. Post-intervention data collection included qualitative data. RESULTS: The co-design process resulted in a strong and engaged partnership between the university team and the provider. There were significant challenges in implementing the intervention including having two additional partner organisations dropping out of the partnership just after the initial implementation phase. However, a flexible and adaptable partnership resulted in developing two distinct lifestyle interventions run with 32 Māori men (in two different cohorts of 8 and 24). All but one in the first cohort completed the programme. The first cohort had a modest although statistically insignificant improvement in weight loss (d = 1.04) and body mass index (BMI; d = 1.08). The second cohort had a significant reduction in weight loss (d = 1.16) and BMI (d = 1.15). They also had a significant increase in health-related quality of life (d = 1.7) and self-rated health (d = 2.0). CONCLUSION: The HPW Framework appears to be well suited to advance implementation science for Indigenous communities in general and Māori in particular. The framework has promise as a policy and planning tool to evaluate and design interventions for chronic disease prevention in Indigenous communities. Despite this promise, there are structural challenges in developing and implementing interventions to address health inequities. TRIAL REGISTRATION: Retrospectively registered, Australia New Zealand Clinical Trials Registry, ACTRN12619001783112.

text: A case study of using the He Pikinga Waiora Implementation Framework: Challenges and successes in implementing a twelve-week lifestyle intervention to reduce weight in Māori men at risk of diabetes, cardiovascular disease and obesity BACKGROUND: Māori men have stark health inequities around non-communicable diseases. This study describes the case of a partnership attempting to develop and implement a culturally centred intervention through a collaborative partnership to potentially address the inequities. In particular, the partnership followed a participatory, co-design approach using the He Pikinga Waiora (HPW) Implementation Framework; the study presents lessons learnt in addressing health inequities following this framework. METHODS: The partnership involved a university research team and a Māori community health provider. They engaged with other stakeholders and several cohorts of Māori men through a co-design process to adapt a 12-week lifestyle intervention. The co-design process was documented through meeting notes and interviews with partners. Two cohorts participated in separate single group pre-intervention/post-intervention designs with multi-method data collection. Key outcome measures included weight loss, self-reported health, physical activity, and nutrition. Post-intervention data collection included qualitative data. RESULTS: The co-design process resulted in a strong and engaged partnership between the university team and the provider. There were significant challenges in implementing the intervention including having two additional partner organisations dropping out of the partnership just after the initial implementation phase. However, a flexible and adaptable partnership resulted in developing two distinct lifestyle interventions run with 32 Māori men (in two different cohorts of 8 and 24). All but one in the first cohort completed the programme. The first cohort had a modest although statistically insignificant improvement in weight loss (d = 1.04) and body mass index (BMI; d = 1.08). The second cohort had a significant reduction in weight loss (d = 1.16) and BMI (d = 1.15). They also had a significant increase in health-related quality of life (d = 1.7) and self-rated health (d = 2.0). CONCLUSION: The HPW Framework appears to be well suited to advance implementation science for Indigenous communities in general and Māori in particular. The framework has promise as a policy and planning tool to evaluate and design interventions for chronic disease prevention in Indigenous communities. Despite this promise, there are structural challenges in developing and implementing interventions to address health inequities. TRIAL REGISTRATION: Retrospectively registered, Australia New Zealand Clinical Trials Registry, ACTRN12619001783112.

year: 2020