Whole Document restricted for copyright reasons. / The Ouvea Parakeet Eunymphicus cornutus uvaeensis, is an endangered bird endemic to Ouvea, Loyalty Islands, in the New Caledonian archipelago. Its population is estimated to be 300-600 birds, mainly in patches of forest in the north, with few parakeets in the centre and the south of the island. Its main habitat is high forest mixed with Melanesian fields. Within habitat distribution is very patchy, with an apparent site attachment during the breeding season. Radio tracking revealed that the home range of juveniles was small, and no dispersal was observed. The diet of the parakeets comprises the seeds and fruits of more than 23 plant species, including Ficus spp., Carica papaya and Rhamnella vitiensis. These plants have a long and asynchronous fruiting season, leading to an apparent abundance of food during the year. The number of breeding pairs was correlated with the density of potential nest sites in the three study areas, suggesting a nest site limitation. The length of the breeding season (August until January) allows the occurrence of double clutches. The parakeets nest in secondary cavities of only five species of trees (90% n Syzygium pseudopinnatum and Mimusops elengii). The clutch size is 2.9 eggs (range 2-4), of which on average 2.6 chicks hatch, 1.65 fledge, but only 0.75 per breeding pair is still alive 30 days after fledging. The main causes of loss are starvation of the third sibling due to hatching asynchrony, human harvest, and raptor predation after fledging. Ouvea is free of Ship Rat Rattus rattus and Norway Rat R. norvegicus. Kiore R. exulans, the rat present, is responsible for only a few predations at nests. The main predators are the Brown Goshawk Accipiter fasciatus, and humans that capture chicks to sell them as pets. 15-30 chicks are still captured every year and sold outside Ouvea. A population viability analysis of the Ouvea Parakeet shows that, with the current carrying capacity, this harvest is not sustainable and would eventually lead to extinction. Long-term survival would be best secured by establishing another population of 4-500 birds in the south of Ouvea, by increasing carrying capacity through habitat protection, nest site provision and restoration, decreasing the harvest and preventing the introduction of Ship Rat in Ouvea.

The first aim of this thesis is an introduction to some basic aspects of multivariate control theory which are relevant to the question of how the brain controls movements. A regulator is a device which forces a system to follow a specified trajectory in the presence of perturbations which might cause it to diverge from that trajectory. Regulation involves constructing an additional control input which depends upon the difference between the actual system state and the desired state. This requires the construction of a state estimate from raw data about system input and output. For effective state estimation, the sensor input gain to the state estimator needs to be time-varying. Under certain assumptions, the appropriate input gain can be specified analytically. The feedback regulation signal can then be constructed as a function of the state estimate. For effective regulation, the gain of the feedback function has to vary during maneuvers. Under certain assumptions an appropriate feedback gain can be specified analytically. The state observer input gain equations have a simple relationship to the feedback gain equations, so that gain specification is essentially the same task in each case. Cerebellar research has been dominated for the past 25 years by the theories of James Albus and David Marr. These mathematicians proposed similar models in which certain synapses in the cerebellar cortex are continuously modified by experience in such a way that movements which are consistently repeated under a given set of circumstances come to be performed automatically by the cerebellum. Much experimental work has focussed on the role of the vestibulo-cerebellum in fine control and learning of the vestibulo-ocular reflex. The state of the art along this line is formally described by Fujita's adaptive filter model of the cerebellar cortex. In chapter 4 it is shown that a basic feature of Fujita's model is inconsistent with available evidence. The 'Tensorial theory of brain function' is discussed in chapter 5. This is a novel theory of brain function which has been used in an attempt two explain cerebellar function. The attempt is a failure, based on sophistocated misconceptions and flawed by poor reasoning and clumsy analysis. The approach serves to confuse rather than clarify the question of cerebellar function. The final chapter of the first part of the thesis presents a basis for a new approach to cerebellar function based on the engineering theory of control of multivariate dynamical systems. It is proposed that the cerebellum is involved in movement regulation by controlling the gains of brainstem motor pathways, and in mapping the animal's environment by controlling the gains of sensory inputs to the midbrain. While learning undoubtedly does occur in the cerebellar cortex, this is not specifically a 'learning device', as commonly conceived. The second part of the thesis is concerned with the development and application of a method of system identification for characterising the dynamics of the vestibulo-ocular reflex and its components in an elasmobranch. The chosen method involves pulse-rate modulated bilateral electrical stimulation of the horizontal semicircular canal ampullary nerves. This produces a synthetic vestibulo-ocular reflex in a stationary preparation. The stimulus pattern is a pseudorandom binary sequence of pulse rates, so that cross-correlation of the stimulus pattern with the response signal gives a Unit Impulse Response dynamic signature for the system. Computer software for signal generation, recording, analysis and display was written by the author. The identification system was applied first to characterise the dynamics of the eye movement response to horizontal canal ampullary nerve stimulation, and compare this to the dynamics of the eye motor plant alone. The eye motor preparation acts as a first order low-pass filter with a time constant of about 0.2 seconds (16°C), while the ampullary preparation acts as a second order low-pass filter with a dominant time constant of about 0.75 seconds (16°C). Central pathways of the elasmobranch vestibulo-ocular reflex extend the time constant of the motor plant by a factor of 3-4, as in other animals. Eye movements predicted by fitted linear models accurately mimic eye movements recorded during experiments, suggesting both that central pathways of the reflex operate normally during this somewhat un-naturally evoked response and that the identification procedure is effective. Furthermore, combination of the ampullary nerve to eye movement transfer function obtained in this study, with head rotation to ampullary nerve transfer functions obtained by other workers, gives a consistent picture of elasmobranch vestibulo-ocular reflex function predicting compensatory eye movements in the band 0.2 - 4.0 Hz., and perhaps higher. The identification method has also been applied to produce models of vestibulocerebellar Purkinje cell dynamics during electrically evoked vestibular eye movements. Linear identification gives a poor characterisation of Purkinje cell activity during the high frequency vestibulo-ocular reflex. This is incompatible with linear phase-compensator models of the cerebellar cortex, but consistent with the reflex gain modulation theory of cerebellar function advocated in the first part of the thesis.

Preferred orientation in the eggshells of the crocodiles, turtles and birds is shown by X-ray diffractometry to develop throughout shell deposition. In all shells, the texture that develops is one in which the (001) plane of the unit cell tends to lie parallel to the shell surface. The degree of texture varies from being high in the calcite of the ratite and tinamou shells and the aragonite of the turtle shells to low in the calcite of the crocodilian and carinate shells. A model is proposed for the deposition of the entire eggshell. This model explains the observed textures and fracture morphologies of the shells. In each shell column, crystal deposition is initiated at a single location, from which growth fans out at all angles to the shell normal. In both calcitic and aragonitic shells, growth is in the [001] direction, resulting in an increase in the degree of (001) preferred orientation with distance from nucleation. Where there is unhindered crystal growth, the shells show a crystalline fracture morphology, and the degree of texture that develops is a simple function of the column radius. This type of growth makes up the whole of the turtle shell, the inner 0.3 to 0.4 of the thick ratite shells and the cone layer of the other avian shells. At the start of the central layer of the avian shell, the onset of protein deposition coincides with a hindrance to texture development, which thereafter proceeds at a lower rate. A further hindrance occurs about half-way through the shell, probably caused by a change in the physical characteristics of the protein network. The degree of texture that develops in the avian shell is a function of the column radius and the degree of physical hindrance presented by the protein network. The central layer of the avian shell has a composite fracture morphology resulting from the intermingling of the network with the inorganic phase. The organic component does not appear to control crystal growth as previously believed, but instead acts as a reinforcing fibrous network.

Experiments on the responses to osmotic stress and desiccation are reported for several species of New Zealand littoral chitons. Qualitative and quantitative studies on the ecology of the common Auckland species have been undertaken, with special reference to microhabitat conditions. The micro-anatomy of the dorsal sensory organs has been studied, and related to the comparative responses to light stimuli, and experiments involving interference with these organs. Sypharochiton pelliserpentis was found t o be an osmo-conformer, showing only limited volume regulation but a wide tolerance to salinity fluctuations. Size of the animal had a negligible effect on the osmotic response, and it is likely that other chitons are osmo-conformers but with less tolerance of osmotic stress. Animals of this species were better able to resist the effects of desiccation than several other chitons. This resulted from a kinetic behaviour pattern in response to low humidities causing aggregation in the laboratory, and a well developed tolerance of extreme water loss, Sypharochiton Pelliserpentis colonises a wide rage of microhabitats on rock surfaces, some exposed to wide salinity changes (13.28°/oo to 45 .80°/ooS) between tides, and others exposed t o drying. Population size structures indicate that exposure t o desiccation is likely t o be more important than osmotic stress in controlling populations, and microhabitat more important than tidal level. The other chitons studied were restricted to pools, beneath boulders or to wave-splashed situations which did not dry. One very fast-moving chiton, Ischnochiton maorianus exhibited photo-negative orientation and the 'shadow response', the full range of reactions to light stimuli yet reported in chitons. It possesses only the megalaesthete type of dorsel sensory receptor. Experiments showed masking or abrading these organs to affect the rate of response, and it is concluded that at least one of their functions is light reception. Hithochiton neglectus, a species possessing well developed extra-pigmental ocelli, did not show such clear responses to light. Problems of the structure and function of these organs are discussed.

The skua (Family Stercorariidae) are a group of large, gull-like, predatory seabirds. Two skua species are found in the Antarctic region; the south polar skua (Catharacta maccormicki) and the brown skua (C. lonnbergi). The breeding distribution of the former, is restricted to the Antarctic continent and nearby islands, while the latter has a circumpolar distribution which extends northward from the Antarctic Peninsula and includes many of the Southern Ocean islands. The south polar skua is strictly monogamous, while in contrast, a number of populations of brown skua are comprised in part of communally breeding groups. The brown skua represents the only known example of a communally breeding seabird. In every skua species, breeding females are on average larger and heavier than males. However, in most skua species this dimorphism is relatively small and is of only limited use in sexing individuals. The discovery of sex-specific fragments in the DNA fingerprints of the south polar skua is reported. The multilocus probe pV47-2 hybridised to Hae III restriction fragments which were present exclusively in females and therefore presumably W-linked. The presence of these sex-specific fragments were used to identify female adults and chicks. In addition, the use of these fragments as potentially informative maternal markers is discussed. The parentage of the 13 families from two populations from Ross Island, Antarctica, determined by DNA fingerprinting, revealed a single instance of extra-pair paternity and a single instance of a chick which was parented by neither resident adult. The most likely explanation for the latter is the 'adoption' of a chick from a neighbouring territory. Similarly, DNA fingerprinting was used to assign the sex of individuals of brown skua from a population which breeds on the Chatham Islands, New Zealand. A large proportion of the Chatham Islands population breed in communal groups. Each communal group was shown to be comprised of a single female and two or more males. Consequently, the overall sex ratio amongst breeding birds was biased, with almost twice the number of males as females. In contrast the sex ratio amongst fledgling chicks did not differ significantly from 1:1. The patterns of reproductive success in breeding pairs and communal groups of the brown skua from the Chatham Islands population were determined using multilocus DNA fingerprinting. Sixteen breeding groups were examined, the parentage of 45 chicks produced over three breeding seasons was established using the probes 33.15 and 33.6. No evidence was found of either extra-pair paternity or extra-group fertilisation and there was no evidence of egg dumping by females in any breeding group. These results suggest that long-term banding records for breeding pairs and communal groups accurately reflect the overall reproductive success of these individual groups. In addition, preliminary band sharing analysis indicated that adult members of communal groups were not closely related. These findings are also supported by banding records and are in contrast to the findings of the majority of communally breeding species studied. In the 10 communally breeding groups examined, multiple paternity within a clutch was recorded on two of the 12 occasions in which two chicks were reared. Furthermore, analysis of parentage of the chicks belonging to communal groups in which the adults had remained unchanged for two or more seasons showed that some males had variable reproductive success in different seasons. These records suggest that estimates of reproductive success of individuals based on a single season's data can be misleading. Should temporal changes in paternity (and/or maternity) be shown to be common phenomena in other species, this would have major implications for the interpretation of many parentage studies. The explanation of altruistic behaviour is one of the central issues in contemporary evolutionary theory and behavioural ecology. One of the best known examples of apparent altruism is the helping behaviour which occurs in communal breeding groups such as those found in the brown skua. Within these groups individuals often help to raise offspring which are not their own. This behaviour is an apparent enigma in a world in which organisms are assumed to act in a selfish manner. Consequently, this behaviour has become a focal example at the centre of much evolutionary debate. A variety of theories have been suggested to explain helping behaviour, the most recent is that helping is an unselected consequence of the evolution of communal breeding. This hypothesis is discussed in relation to the recent literature and it is concluded that it does little to advance the current debate. An alternative theoretical approach to helping behaviour is outlined. In conclusion the general findings from the investigation of communal breeding in the brown skua are summarised and these findings are discussed. Finally, possible areas of future research are outlined. / Whole document restricted, but available by request, use the feedback form to request access.

The Pinnotheridae is a family of decapod crustaceans comprising more than 120 mostly microphagous and commensal species. As symbionts of a variety of aquatic invertebrates, pinnotherids typically live in an intimate association with their host depending on it for an almost lifelong source of nourishment and shelter, together with a site for mating. The New Zealand pinnotherid fauna was thought to comprise only one species, Pinnotheres novaezelandiae Filhol, associated with a multitude of hosts. Recently, however, a separate species, P. atrinicola Page, has been described which is regarded as being host specific to the horse mussel Atrina zelandica Gray. In this context, the relationship between pea crabs and their hosts is of special interest, and is the focus of this thesis. An investigation into the population dynamics of the symbiotic relationship between P novaezelandiae and its host, the green-lip mussel Perna canaliculus, at Westmere Reef, Auckland between May 1986 and July 1988 is reported. Ovigerous females and Stage I males and females were found throughout the sampling period, indicating that reproduction is continuous in this species. The developmental composition of the pea crab population reveals that soft-shelled males, usually regarded as an anomalous instar, formed a significant component of the pea crab population at all times. It is suggested that these individuals represent a distinct facies, analogous to the Stage II female instar. The presence of a pea crab was found to have a highly significant detrimental effect on mussel condition. Analysis of the distribution of pea crabs among the mussel population indicates mature crabs display a repulsed distribution favouring to live a solitary existence, whereas younger (pre-hard and Stage I) crabs showed a random distribution in broad agreement with a theoretical Poisson distribution. The biological status of the two described taxa was investigated by a survey of electrophoretically detectable genetic variation of populations from throughout the North Island of New Zealand. Pea crabs from 18 host populations from nine geographically disparate localities were subjected to cellulose acetate and poly-acrylamide electrophoresis. Forty-one enzyme systems were screened for polymorphism. Clearly resolved enzyme phenotypes were obtained at 23 presumptive loci, of which l5 exhibited polymorphism. An analysis of electromorph frequency data revealed that both taxa are highly genetically structured and typified by high levels of polymorphism and heterozygosity; results atypical of brachyuran crabs. P- atrinicola was found to exhibit strong patterns of geographic differentiation and clinal variation in electromorph frequency. Of particular significance is the pattern of genetic differentiation observed among populations of p. novaezelandiae. Hierarchical F-statistics indicated that the preponderance of inter-population differentiation can be attributed to differences in electromorph frequency among host-associated populations of P. novaezelandiae within a sampling locality. Geographic differentiation was a comparatively insignificant factor in the structuring of the sampled P. novaezelandiae populations. Individuals belonging to two genetically very distinct units were found within a newly recorded host species, Mactra ovata ovata Gray at Green and Wood Bays, Manukau Harbour. Hardy-Weinberg analyses indicate the host-associated populations of P. novaezelandiae exhibit such a pronounced pattern of homozygote excess and disturbance from genetic equilibrium in sympatry that it is unreasonable to consider them as a single panmictic population. It is concluded that significant biological discontinuities based on host origin exist within the currently recognised taxon. Such a conclusion is supported by data presented on qualitative differences in host recognition observed between different host-associated populations of P. novaezelandiae. Conservatively these discontinuities indicate host race development, although a viable alternate hypothesis would be the presence of cryptic, host-specific biological species within P. novaezelandiae. Hostrace development as found here is a well recognised phenomenon in insect-host and parasitoid-host relationships, although little studied in marine symbiotic relationships. Such a phenomenon has important implications for ecological, behavioural and physiological studies on marine symbionts in general.

The acid-mucopolysaccharides (AMPs) found within the Demospongiae have been identified by electrophoresis, and their localization within adult tissues, aggregates and metamorphosing larvae have been examined by histological and ultrastructural techniques. Electrophoresis of the AMPs extracted from a selection of Demospongiae showed that most of the AMPs typical of vertebrate connective tissues were present. No evidence was found in this study to suggest a possible role whereby the presence or absence of sulphated AMPs could be of use in sponge taxonomy. Histochemical studies on the cytological localization of AMPs in both adult tissues and developing larvae also failed to provide any evidence to support the previous hypothesis that AMP localization could be used as an aid in the classification of the Demospongiae. Ultrastructural studies on the localization of AMPs indicated several mechanisms whereby AMPs could contribute to sponge cohesion. The AMPs associated with collagen fibrils were found to be arranged in a way essentially similar to that already described for mammals, and various other lines of evidence confirm the similarity of the sponge mesohyl to vertebrate connective tissue. There is, however, no need to imply a direct evolutionary relationship. The possible role of AMPs in both cell-cell and cell-substrate adhesion has been examined in detail. Evidence is presented for the existence of an aggregation factor in Microciona coccinea. The factor has been shown to be a proteoglycan in a closely related species of sponge, and although conclusive evidence on the role of factor is lacking it is interpreted by many workers to be a surface attached molecule involved in adhesion. No evidence was obtained in this study to confirm localization of the factor at the sponge cell surface, but this may be a result of limitations in present ultrastructural techniques. Initial cell contact in cell-cell adhesion during aggregation was seen to occur in the regions of narrow extensions of the plasmalemmae termed membrane bridges. Structures of this sort have been proposed on physical grounds as one means by which cells may overcome the electric repulsive barrier between them to make adhesion by ionic bridging. Adhesion to the substrate in metamorphosing sponge larvae was seen to be mediated by a groundmat which is believed to be secreted by the larva, and which contains a granular component as well as collagen and fine filaments. The role of junctions in cell-cell adhesion was examined in detail in adult sponges and in aggregated cells. The presence of the cell junctions characteristic of other organisms could not be convincingly demonstrated in sponge tissues, and it seems probable that structures other than the typical cell junctions may be involved in communication and adhesion within sponges. An unusual AMP surface coat – the larval coat – is described from the surface of the T-pinacocytes in metamorphosing larvae of Halichondria moorei. The similarity of this coat in some respects to the fuzzy surface coat of amoebae is noted, and some of its possible functions are discussed.

The New Zealand glowworm Arachnocampa luminosa (Diptera: Mycetophilidae) provides the national tourist industry with a unique attraction. The Glowworm Cave at Waitomo has an international reputation for the bioluminescent display produced by A. luminosa. The aim of the present study was to investigate glowworm ecology in the tourist caves at Waitomo, the results to provide factual information so that scientifically sound management procedures could be devised to ensure the long term survival of the population. The literature on all aspects of A. luminosa is reviewed. A continuous cycle of development occurs with most stages present throughout the year. However, the majority of the larval population pupates in late winter/early spring, producing a new generation in spring/early summer. There are five larval instars; the time for individual development in the Glowworm Cave varies considerably but is estimated to take 5 months on average. Distribution of glowworms is dependent on an adequate food supply, cool, moist climate and a suitable horizontal rock surface. Their diet consists of chironomids with some tipulids, ephemeropterans and trichopterans, most of which emerge inside the cave. Factors likely to influence distribution and productivity of benthic fauna in the cave are reviewed, including the importance of flooding and stream drift fauna in restocking the cave. Mortality is caused by two species of opiliones, cannibalism and a fungal pathogen identified as Tolypocladium sp. (Moniliales). Preliminary experiments with Tolypocladium indicate that the higher temperatures of the Glowworm Cave may be responsible for the prevalence of the fungus compared with non-tourist caves in the district. Observations on cave climate showed that the Glowworm Cave now has a higher range of temperature and relative humidity compared with earlier records and non-tourist caves at Waitomo. This is attributed in part to the free flow of air that occurs between the two entrances of the cave and the outside atmosphere. Reasons for the decline in the glowworm display that has occurred in the past few years are discussed. The installation of an open grille on the Top Entrance of the Glowworm Cave in 1975 is suggested as one of the main factors responsible. Future research projects are mentioned, together with recommendations for cave management related to glowworm ecology.

The structure and function of septate junctions have been studied by ultrastructural techniques in a wide range of invertebrate phyla. Techniques have included conventional and tracer impregnated tissue thin sectioning, and freeze-fracture of both fixed and unfixed tissue. Standard and goniometer stage transmission electron microscopy has been used. Work in this study has been concentrated mainly on the lower invertebrate phyla in which the simplest forms of junction might be seen, and on the higher invertebrate phyla. This latter group is of special interest in the transition region between the invertebrate and vertebrate phyla. Six new types of septate junction and a form of tight junction have been found in invertebrate phyla and are described. Two of these new septate junctions occur in each of the phyla Coelenterata, Echinodermata and Hemichordata. The tight junction occurs in the phylum Tunicata. Further data has also been obtained on five of the six previously described types of septate junction. The distribution of all twelve types within the invertebrates and their phylogenetic relationships are discussed. Work with the goniometer stage has aided in interpreting junctional structures. The results have revealed several features of the septate junction that support the idea that it has a mainly occluding function analogous to that of the vertebrate tight junction. In addition, an anastomosing septate junction has been found in the Echinodermata which is postulated to be a structural intermediate between the invertebrate septate junction and the vertebrate tight junction. A hypothesis is proposed suggesting how the septate junction might have evolved into the vertebrate tight junction. Tricellular junctional regions of most of the septate junction types are noted and briefly described.

In her classic review of the echinoderms, Hyman (1955), describes the ophiuroids as "the most successful echinoderm group living today". This success has largely been attributed to both their smaller size and their remarkable agility. Many authors have commented on their great importance in the bionomics of the sea; various species participate in food chains involving demersal fish and many others serve as agents for the disposal and recycling of organic materials on the benthos. Their wide occurrence in the marine environment, coupled with their dense numbers, has led to their inclusion in the nomenclature of benthic communities and sub-comnunities, particularly in European waters. Some 1,900 extant species, being referred to 255 genera, have no been described (Fell, 1960).