The doctoral studies described in this thesis involve the phenotypic characterization of the tremor rat, an animal model of Canavan disease, and a proof of principle gene transfer study in this model. The phenotype of the tremor rat is examined at the genetic, molecular, cellular, neurochemical, physical and behavioural levels, and tremor mutants are described within the context of Canavan disease. Tremor mutants appear to share many phenotypes with both human patients and to the knock-out mouse model. The deletion of aspartoacylase results in a total loss of the capacity to metabolize N-acetyl-aspartate to acetate and aspartate in brain, leading to elevations in brain N-acetyl-aspartate levels, changes in cell and tissue morphology, and physical and behavioural deficits including mild akinesia and loss of normal motor coordination and balance. Parallel to this work was the development of a gene transfer approach to treat Canavan disease, involving Adeno-associated virus mediated delivery of aspartoacylase to the mammalian central nervous system. Gene transfer was undertaken in tremor rat mutants, and analysis was made of gene expression and function as well as the effect of aspartoacylase expression on improving the phenotypic deficits observed in mutant animals. Gene expression was observed at the RNA and protein level, with recombinant protein observed in cell soma and processes. Although not significant the data suggested a trend of decreased NAA levels after aspartoacylase transfer in comparison to animals injected with a vector encoding green fluorescent protein. Improvement was noted in the rotorod phenotype with mutant animals receiving aspartoacylase gene transfer performing better at tests of balance and coordinated locomotion than animals receiving a control vector. The study provided evidence that Adeno-associated virus mediated aspartoacylase gene transfer to the brain improves some of the deficits in tremor mutants, and supports the rationale of human gene transfer for Canavan disease. / Subscription resource available via Digital Dissertations only.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.

<p dir="ltr">The Leatherback Sea Turtle (<i>Dermochelys coriacea</i>) is a globally vulnerable species suffering from declining populations due to anthropogenic pressures. There are seven recognized Leatherback Sea Turtle regional management units; however, the Southeast Atlantic unit is considered data deficient. Bioko Island, Equatorial Guinea, is a primary nesting rookery for the Southeast Atlantic regional management unit and has some of the world’s highest numbers of nesting Leatherback Sea Turtles. Despite Bioko Island’s importance to the species, little is known about the nesting ecology or post-nesting migratory movement and behaviors of its nesting Leatherback Sea Turtles. Here, I present the findings of two individual research projects on the nesting ecology of Leatherback Sea Turtles on Bioko Island. First, I explored the long-term clutch success rates (i.e., hatching success and emergence success) of <i>in situ</i> Leatherback Sea Turtle nests on Bioko and searched for associated variables. I found significant spatiotemporal variation over nine nesting seasons, likely driven by individual beach characteristics rather than regional climate patterns. Secondly, I described a novel effort to use solar-reliant towable transmitters to track the post-nesting migratory movements and behaviors of Leatherback Sea Turtles nesting on Bioko Island. With the results from each project, I make recommendations to further the current conservation and research initiatives of Leatherback Sea Turtles.</p>

<p dir="ltr">The Northwest Atlantic Ocean, which surrounds the US eastern coastline, is an area rich in marine life. The US eastern coastline is also highly urbanized, resulting in a lot of pollutants (like heavy metals) entering the marine environment. This is of concern for long-lived marine species like sea turtles. Since sea turtles are long-lived and highly migratory, their tissues can often incorporate these pollutants through environmental and dietary exposure. I collected tissue samples from 5 different sea turtle populations in the Northwest Atlantic and analyzed them for concentrations of silver (Ag), aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), selenium (Se) and zinc (Zn) using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The first chapter looks at skin (reflects exposure ~1 year ago) and scute (reflects exposure from 4-6 years ago) samples collected during necropsies of juvenile green (<i>Chelonia mydas</i>) (n=8), Kemp’s ridley (<i>Lepidochelys kempii</i>) (n=30) and loggerhead (<i>Caretta caretta</i>) (n=17) turtles that were found cold-stunned in Cape Cod Bay, Massachusetts. In scute samples, the heavy metal with the highest concentration for green turtles was iron, zinc for loggerhead turtles, and arsenic for Kemp’s ridley turtles. In skin samples, the heavy metal with the highest concentration for green turtles was iron, arsenic for loggerhead turtles, and aluminum for Kemp’s ridley turtles. Overall, I found scute samples to have higher heavy metal concentrations than skin samples. The second chapter looks at scute samples collected from loggerhead turtles of different life stages. These samples were collected during necropsies of cold-stunned loggerhead turtles from Cape Cod Bay, Massachusetts (CCB; n=17), as well as from live loggerhead turtles in the Mid-Atlantic Bight (MAB; n=37) and off the coast of North Carolina (NC; n=9). We also collected commonly known loggerhead turtle prey items including whelk (<i>Buccinum undatum</i>) (n=12), Atlantic scallop (<i>Placopecten magellanicus)</i> (n=10) and Jonah crab (<i>Cancer borealis</i>) (n=5) from the Mid-Atlantic Bight region to study the occurrence of biomagnification through trophic pathways. NC loggerhead turtles had higher heavy metal concentrations than other locations except for cadmium and zinc, where CCB loggerhead turtles were higher. I found that all heavy metals except silver, cadmium, and lead appear to be biomagnified (TTF>1) in loggerhead turtles. These two chapters provided baseline information on heavy metal concentrations in sea turtles in east coast US.</p>

Knowledge of the interactions among species and communities is vital for their management and protection. Increasingly, the role of marine protected areas in this regard is being recognised, primarily because of the potential for previously-harvested species to increase in density and biomass, and the linkages among species to be restored. Monitoring and research was conducted within and surrounding two marine reserves on the east coast of the North Island of New Zealand – Te Tapuwae o Rongokako, near Gisborne, and Te Angiangi, south of Napier. The aim was to describe the biological characteristics of spiny lobsters (Jasus edwardsii) in the absence of fishing, and to describe the effects of fishing and protection on lobster populations and the communities of which they are a component. Diver and pot surveys showed that lobsters were significantly more abundant within the reserves than in the surrounding fisheries and that the populations were comprised of a larger proportion of legal-sized individuals. Higher female fecundity within Te Tapuwae o Rongokako Marine Reserve compared with the surrounding fishery was proposed to be primarily a result of increased availability of large males within the reserve. The impact of the fishery on lobsters was also evidenced in the lower tail width to carapace length ratio of the fished population compared to the population within Te Tapuwae o Rongokako Marine Reserve, due to the minimum legal size for Jasus edwardsii in New Zealand being based on tail width. The largest tagging study ever to be conducted in a New Zealand marine reserve showed that sublegal male lobsters within Te Tapuwae o Rongokako Marine Reserve were growing on average faster than the same sized individuals outside the reserve, potentially as a result of the effects of handling and / or size-selective fishing. A decrease in growth rate over time was recorded in male lobsters within the reserve, which coincided with an increase in catch per unit effort and may indicate that density-dependent effects are operating. Distinct seasonal movements of tagged lobsters were recorded, with the vast majority of movements taking place within reefs. Where the boundaries of the reserve crossed reef habitat, significant movement of lobsters across the boundaries occurred. Lobsters within Te Tapuwae o Rongokako Marine Reserve not only exhibited cannibalistic behaviour but foraged during the day, including on intertidal reef platforms at high tide, potentially as a behavioural response to increased competition for food – behaviour not previously reported for this species. Outside the reserve, lobster bait apparently provided an alternative protein source but despite this supplementation of diet, these lobsters were in poorer nutritional condition, as evidenced by their lower body weights relative to carapace length and tail width for both sexes. Lobsters outside the reserve were also significantly more affected by a bacterial infection associated with handling, than lobsters within the reserve. These findings have significant implications for fisheries management and for the design and management of marine protected areas (MPAs). This study demonstrates that many of the biological parameters used in evaluating harvest strategies in the New Zealand lobster fishery may be biased unless collected from populations with a natural size structure, such as may occur within marine protected areas.

Knowledge of the interactions among species and communities is vital for their management and protection. Increasingly, the role of marine protected areas in this regard is being recognised, primarily because of the potential for previously-harvested species to increase in density and biomass, and the linkages among species to be restored. Monitoring and research was conducted within and surrounding two marine reserves on the east coast of the North Island of New Zealand – Te Tapuwae o Rongokako, near Gisborne, and Te Angiangi, south of Napier. The aim was to describe the biological characteristics of spiny lobsters (Jasus edwardsii) in the absence of fishing, and to describe the effects of fishing and protection on lobster populations and the communities of which they are a component. Diver and pot surveys showed that lobsters were significantly more abundant within the reserves than in the surrounding fisheries and that the populations were comprised of a larger proportion of legal-sized individuals. Higher female fecundity within Te Tapuwae o Rongokako Marine Reserve compared with the surrounding fishery was proposed to be primarily a result of increased availability of large males within the reserve. The impact of the fishery on lobsters was also evidenced in the lower tail width to carapace length ratio of the fished population compared to the population within Te Tapuwae o Rongokako Marine Reserve, due to the minimum legal size for Jasus edwardsii in New Zealand being based on tail width. The largest tagging study ever to be conducted in a New Zealand marine reserve showed that sublegal male lobsters within Te Tapuwae o Rongokako Marine Reserve were growing on average faster than the same sized individuals outside the reserve, potentially as a result of the effects of handling and / or size-selective fishing. A decrease in growth rate over time was recorded in male lobsters within the reserve, which coincided with an increase in catch per unit effort and may indicate that density-dependent effects are operating. Distinct seasonal movements of tagged lobsters were recorded, with the vast majority of movements taking place within reefs. Where the boundaries of the reserve crossed reef habitat, significant movement of lobsters across the boundaries occurred. Lobsters within Te Tapuwae o Rongokako Marine Reserve not only exhibited cannibalistic behaviour but foraged during the day, including on intertidal reef platforms at high tide, potentially as a behavioural response to increased competition for food – behaviour not previously reported for this species. Outside the reserve, lobster bait apparently provided an alternative protein source but despite this supplementation of diet, these lobsters were in poorer nutritional condition, as evidenced by their lower body weights relative to carapace length and tail width for both sexes. Lobsters outside the reserve were also significantly more affected by a bacterial infection associated with handling, than lobsters within the reserve. These findings have significant implications for fisheries management and for the design and management of marine protected areas (MPAs). This study demonstrates that many of the biological parameters used in evaluating harvest strategies in the New Zealand lobster fishery may be biased unless collected from populations with a natural size structure, such as may occur within marine protected areas.

Theoretical research has demonstrated that ecological interactions in sympatry or parapatry can generate disruptive selection that in concert with assortative mating can lead to speciation. However, empirical examples are few and restricted to terrestrial and lacustrine systems. New Zealand triplefin fishes (Family Tripterygiidae) are an ideal model system to study speciation in the sea, as they conform to the criteria of an adaptive radiation, being philopatric, speciose and abundant, and having largely sympatric distributions. This thesis investigates two key aspects of the New Zealand triplefin radiation: 1) which ecological traits are under selection?; and 2) which traits are potentially available for the development of assortative mating? Habitat use was identified as a possible key trait for selection and investigated in detail in this thesis. Habitat use of the majority of New Zealand triplefin species was censused quantitatively throughout most of their latitudinal range and analysed using novel statistical methods. Analyses showed that habitat use was highly divergent between species and thus diversification in habitat may have been a major component in the evolution of this clade. The phylogenetic analysis of habitat characters confirmed that there has been rapid evolution in habitat use among species. Habitat selection at settlement was highly species-specific, indicating that interspecific differences in adult habitat use may be the outcome of active habitat choice established at settlement. These species-specific habitat associations showed no evidence for geographic variation in habitat use. Laboratory trials and field observations of the sister-species pair Ruanoho decemdigitatus and R. whero showed that competition was linked with body size, with R. decemdigitatus being the larger and consequently dominant species. The second part of this thesis investigated which traits may have contributed to prezygotic isolation, and thus to assortative mating. Little evidence was found for divergence in breeding season or male colour patterns. However, divergence in habitat affected breeding habitat choice, as triplefins court and mate in the same territory as that occupied year round. This suggests that assortative mating in New Zealand triplefin species could be the by-product of adaptation to habitat resources. Body size affected mate choice and time at first maturity in the Ruanoho sister-species pair, suggesting that size is important in the maintenance of reproductive isolation in these species. Differences in body size may have also lead to assortative mating in other New Zealand triplefin sister-species pairs, as all sister-species pairs differ in maximum body size. The findings of this thesis invoke a strong role for ecologically-based selection in speciation, and support the hypothesis that adaptation to habitat has been a major factor in speciation in this system. / This PhD was funded by the New Zealand Royal Society (Marsden Fund 02-UOA-005 to Kendall Clements), the Tertiary Education Commission (Top Achiever Doctoral Scholarship), and the University of Auckland (University of Auckland Doctoral Scholarship.

Knowledge of the interactions among species and communities is vital for their management and protection. Increasingly, the role of marine protected areas in this regard is being recognised, primarily because of the potential for previously-harvested species to increase in density and biomass, and the linkages among species to be restored. Monitoring and research was conducted within and surrounding two marine reserves on the east coast of the North Island of New Zealand – Te Tapuwae o Rongokako, near Gisborne, and Te Angiangi, south of Napier. The aim was to describe the biological characteristics of spiny lobsters (Jasus edwardsii) in the absence of fishing, and to describe the effects of fishing and protection on lobster populations and the communities of which they are a component. Diver and pot surveys showed that lobsters were significantly more abundant within the reserves than in the surrounding fisheries and that the populations were comprised of a larger proportion of legal-sized individuals. Higher female fecundity within Te Tapuwae o Rongokako Marine Reserve compared with the surrounding fishery was proposed to be primarily a result of increased availability of large males within the reserve. The impact of the fishery on lobsters was also evidenced in the lower tail width to carapace length ratio of the fished population compared to the population within Te Tapuwae o Rongokako Marine Reserve, due to the minimum legal size for Jasus edwardsii in New Zealand being based on tail width. The largest tagging study ever to be conducted in a New Zealand marine reserve showed that sublegal male lobsters within Te Tapuwae o Rongokako Marine Reserve were growing on average faster than the same sized individuals outside the reserve, potentially as a result of the effects of handling and / or size-selective fishing. A decrease in growth rate over time was recorded in male lobsters within the reserve, which coincided with an increase in catch per unit effort and may indicate that density-dependent effects are operating. Distinct seasonal movements of tagged lobsters were recorded, with the vast majority of movements taking place within reefs. Where the boundaries of the reserve crossed reef habitat, significant movement of lobsters across the boundaries occurred. Lobsters within Te Tapuwae o Rongokako Marine Reserve not only exhibited cannibalistic behaviour but foraged during the day, including on intertidal reef platforms at high tide, potentially as a behavioural response to increased competition for food – behaviour not previously reported for this species. Outside the reserve, lobster bait apparently provided an alternative protein source but despite this supplementation of diet, these lobsters were in poorer nutritional condition, as evidenced by their lower body weights relative to carapace length and tail width for both sexes. Lobsters outside the reserve were also significantly more affected by a bacterial infection associated with handling, than lobsters within the reserve. These findings have significant implications for fisheries management and for the design and management of marine protected areas (MPAs). This study demonstrates that many of the biological parameters used in evaluating harvest strategies in the New Zealand lobster fishery may be biased unless collected from populations with a natural size structure, such as may occur within marine protected areas.

Theoretical research has demonstrated that ecological interactions in sympatry or parapatry can generate disruptive selection that in concert with assortative mating can lead to speciation. However, empirical examples are few and restricted to terrestrial and lacustrine systems. New Zealand triplefin fishes (Family Tripterygiidae) are an ideal model system to study speciation in the sea, as they conform to the criteria of an adaptive radiation, being philopatric, speciose and abundant, and having largely sympatric distributions. This thesis investigates two key aspects of the New Zealand triplefin radiation: 1) which ecological traits are under selection?; and 2) which traits are potentially available for the development of assortative mating? Habitat use was identified as a possible key trait for selection and investigated in detail in this thesis. Habitat use of the majority of New Zealand triplefin species was censused quantitatively throughout most of their latitudinal range and analysed using novel statistical methods. Analyses showed that habitat use was highly divergent between species and thus diversification in habitat may have been a major component in the evolution of this clade. The phylogenetic analysis of habitat characters confirmed that there has been rapid evolution in habitat use among species. Habitat selection at settlement was highly species-specific, indicating that interspecific differences in adult habitat use may be the outcome of active habitat choice established at settlement. These species-specific habitat associations showed no evidence for geographic variation in habitat use. Laboratory trials and field observations of the sister-species pair Ruanoho decemdigitatus and R. whero showed that competition was linked with body size, with R. decemdigitatus being the larger and consequently dominant species. The second part of this thesis investigated which traits may have contributed to prezygotic isolation, and thus to assortative mating. Little evidence was found for divergence in breeding season or male colour patterns. However, divergence in habitat affected breeding habitat choice, as triplefins court and mate in the same territory as that occupied year round. This suggests that assortative mating in New Zealand triplefin species could be the by-product of adaptation to habitat resources. Body size affected mate choice and time at first maturity in the Ruanoho sister-species pair, suggesting that size is important in the maintenance of reproductive isolation in these species. Differences in body size may have also lead to assortative mating in other New Zealand triplefin sister-species pairs, as all sister-species pairs differ in maximum body size. The findings of this thesis invoke a strong role for ecologically-based selection in speciation, and support the hypothesis that adaptation to habitat has been a major factor in speciation in this system. / This PhD was funded by the New Zealand Royal Society (Marsden Fund 02-UOA-005 to Kendall Clements), the Tertiary Education Commission (Top Achiever Doctoral Scholarship), and the University of Auckland (University of Auckland Doctoral Scholarship.

Knowledge of the interactions among species and communities is vital for their management and protection. Increasingly, the role of marine protected areas in this regard is being recognised, primarily because of the potential for previously-harvested species to increase in density and biomass, and the linkages among species to be restored. Monitoring and research was conducted within and surrounding two marine reserves on the east coast of the North Island of New Zealand – Te Tapuwae o Rongokako, near Gisborne, and Te Angiangi, south of Napier. The aim was to describe the biological characteristics of spiny lobsters (Jasus edwardsii) in the absence of fishing, and to describe the effects of fishing and protection on lobster populations and the communities of which they are a component. Diver and pot surveys showed that lobsters were significantly more abundant within the reserves than in the surrounding fisheries and that the populations were comprised of a larger proportion of legal-sized individuals. Higher female fecundity within Te Tapuwae o Rongokako Marine Reserve compared with the surrounding fishery was proposed to be primarily a result of increased availability of large males within the reserve. The impact of the fishery on lobsters was also evidenced in the lower tail width to carapace length ratio of the fished population compared to the population within Te Tapuwae o Rongokako Marine Reserve, due to the minimum legal size for Jasus edwardsii in New Zealand being based on tail width. The largest tagging study ever to be conducted in a New Zealand marine reserve showed that sublegal male lobsters within Te Tapuwae o Rongokako Marine Reserve were growing on average faster than the same sized individuals outside the reserve, potentially as a result of the effects of handling and / or size-selective fishing. A decrease in growth rate over time was recorded in male lobsters within the reserve, which coincided with an increase in catch per unit effort and may indicate that density-dependent effects are operating. Distinct seasonal movements of tagged lobsters were recorded, with the vast majority of movements taking place within reefs. Where the boundaries of the reserve crossed reef habitat, significant movement of lobsters across the boundaries occurred. Lobsters within Te Tapuwae o Rongokako Marine Reserve not only exhibited cannibalistic behaviour but foraged during the day, including on intertidal reef platforms at high tide, potentially as a behavioural response to increased competition for food – behaviour not previously reported for this species. Outside the reserve, lobster bait apparently provided an alternative protein source but despite this supplementation of diet, these lobsters were in poorer nutritional condition, as evidenced by their lower body weights relative to carapace length and tail width for both sexes. Lobsters outside the reserve were also significantly more affected by a bacterial infection associated with handling, than lobsters within the reserve. These findings have significant implications for fisheries management and for the design and management of marine protected areas (MPAs). This study demonstrates that many of the biological parameters used in evaluating harvest strategies in the New Zealand lobster fishery may be biased unless collected from populations with a natural size structure, such as may occur within marine protected areas.