The larvae of many Lepidoptera of the family Noctuidae have both green and brown forms. This trait had never been studied in depth. (Chapter 1) Larvae of Phlogophora meticulosa exhibit considerable colour variation. A method was developed to score larval colour. (Chapter 2) Eight colour types were defined, these being named "early green", "3rd instar green", and the main colour types "green, olive, brown, plain yellow, yellow-green and yellow-brown". Larval colour in the 1st, 2nd and sometimes 3rd instars is determined by foodplant colour. The seven colour types found in the late in stars, (3rd instar green is replaced by the green main colour type in subsequent instars), are controlled by five unlinked major genes which have a total of eleven alleles. The system involves a complex arrangement of dominance and epistatic effects. (Chapter 3) The change from foodplant to genetic control of larval colour is correlated with a change from a positive to a negative phototactic response. (Chapter 4) Study of allelic and phenotypic frequencies in wild populations has indicated that the genetic polymorphism is balanced from year to year, although the frequencies of some alleles show seasonal variation. (Chapter 5) Tests to determine the nature of the selective forces, which maintain the polymorphism, have indicated that choice of mate is random. Heterozygote advantage is implicated in the maintenance of at least two of the genes. (Chapter 6) Selection due to viral infection and parasitism both affect the maintenance of at least one gene, and beetle and small mammal predation may also do so. (Chapter 7) Experiments on the effects of bird predation have uncovered a complicated system of bird-larval morph relationships. (Chapter 8) Arguments are put forward to explain the switch from foodplant to genetic control of colour, and to explain the lack of linkage between the five major genes controlling larval colour. The relative importance of the selective agencies scrutinised is considered. It is suggested that bird predation is extremely important in the maintenance of the genetic system. The degree to which larval morphs are exposed to differential predation by birds is determined by the cryptic qualities of the larvae, and, because birds select apostatically to some extent, their abundance. Further lines of research are suggested (Chapter 9).

This thesis comprises a study of the physiological characteristics of the haemoglobins of several worms in relation to their habitats and life-styles. A method for measuring oxygen-equilibrium in microlitre quantities of whole blood is described. Equilibrium data were determined for the vascular bloods of the polychaetes Cirriformia tentaculata, Terebella lapidaria, Arenicola marina, and Neoamphitrite figulus. Coelomic haemoglobins were studied in T. lapidaria, Notomastus latericeus, Capitella capitata and the echiuroid Thalassemia neptuni. These bloods differed in oxygen affinity (p50) and the shape of the equilibrium curve (N). Magelona is unique in the annelids in having haemerythrin and some physico-chemical properties are compared with the sipunculid pigment in Golfingia elongata. Some physico-chemical properties of chlorocruorin, a pigment peculiar to polychaetes, were obtained from Sabella penicillus, Mercierella enigmatica, and Pherusa plumosa and their properties compared. Assumptions of in vivo pH values were critically examined and large intra-and interspecific differences were measured, some being outside the pH range used in Bohr shift studies. Carbonic anhydrase kinetics of Arenicola marina blood were compared with a bovine preparation. Inhibition with acetazolamide suggested participation in the removal of metabolic CO₂. The enzyme was looked for in several other polychaete tissues using a micro method developed for this study. The possibility of a storage function of a coelomic haemoglobin was examined in T. lapidaria. Aerial respiration rates in CO₂-free and 2.5% CO₂ atmospheres at several temperatures were determined. The use of CO₂ buffers is thought to be an innovation. The effect of temperature on the p50's of T. lapidaria, A. marina, and Neanthes virens haemoglobins was analysed according to the van't Hoff integration. No molecular adaptations reducing temperature sensitivity were found. The emergent theme was that the polychaetes studied were not so much adapted to a range of environmental variables (since they often created their own environment) but rather to a way of life.

This work is concerned with processes of thermal acclimation in the freshwater pulmonate, Lymnaea stagnalis. Three physiological functions were studied: heart rate, rate of oxygen consumption and assimilation efficiency, Seasonal changes in rate-temperature curves of the first two processes were investigated and compared with alterations induced by exposure to constant temperatures in the laboratory. Simple comparisons were made to determine whether season affected assimilation efficiency. The aims of the investigation were to show whether the measured physiological functions exhibited acclimatory responses to determine the precise nature and interrelationship of any such adaptations, and to suggest possible mechanisms responsible for the changes. It was found that changes in the heart rate-temperature relation were induced both by season and by laboratory acclimation. Results of the seasonal study showed apparent capacity adaptations, so that winter animals had a higher heart rate than summer animals at temperatures between 15 and 25 degrees C, and also resistance adaptations, which gave summer animals increased resistance to heat and winter animals greater tolerance of cold. Laboratory acclimation induced resistance adaptations at both temperature extremes but capacity adaptation was absent. Observed bimodality in heart rate-temperature curves of both studies indicated that control of heart rate is complex. These results are discussed further with reference to changes in physiological mechanisms. Seasonal changes occurred in the size-rate regression for oxygen consumption and in the general shape of the rate temporature curves. There was evidence for a 'reverse acclimation' in response to seasonal changes in temperature. These seasonal responses were not produced, however, by exposure to constant temperature in the laboratory. It is proposed that the observed changes resulted essentially from reproductive activity and seasonal changes in dietary conditions. Hormonal influences are thought to be most important in mediating these changes. No significant differences were found in the assimilation efficiencies of winter and summer snails. Results of this and other studies suggest that the assimilation function does not show acclimatory changes in response to either temperature or season. The results are discussed in relation to the known biology of Lymnaea stagnalis and with reference to fundamental temperature acclimation.

The subject of this thesis is the identification and functional characterization of sea urchin neuropeptides. Neuropeptides are important mediators of neural signalling in all known animals with a nervous system, including bilaterians, ctenophorans, and cnidarians. Sea urchin neuropeptides are of particular interest for three significant reasons; echinoderms have a radically different secondarily-derived pentaradial body structure, sea urchins have served as model organisms for research into embryonic development, and thirdly because the genome of a sea urchin, the purple sea urchin Strongylocentrotus purpuratus (Stimpson, 1857) has been sequenced (Sodergren et al., 2006). Only one family of neuropeptides, the SALMFamides, has previously been characterized in all classes of the phylum Echinodermata. The thesis reports the identification of putative neuropeptide GPCRs and at least seven novel sea urchin neuropeptide genes using genomic and Expressed Sequence Tag (EST) analysis. The novel sea urchin neuropeptides identified include putative homologues of vasotocin, the sea cucumber neuropeptide NGIWYamide, thyrotropin-releasing hormone, gonadotropin-releasing hormone, and calcitonin. A further three peptide precursor genes encoding peptides lacking strong homology to any known peptides were also identified and the peptides have been named GKamides and Pedal Peptide-like Neuropeptides. Two of the peptide precursor genes, those encoding peptides homologous to vasotocin and NGIWYamide, also each encode neurophysin domains, which have previously only been identified in association with vasopressin/oxytocin-like peptides. Biochemical and pharmacological techniques were employed to investigate the occurrence and functions of the putative neuropeptides identified. These included mass spectroscopy and in vitro bioassays, the former to detect the putative novel neuropeptides identified in this study and the latter to investigate bioactivity of the peptides in sea urchins. The thesis provides evidence of the neural expression and bioactivity of novel sea urchin neuropeptides and contributes to our understanding of the role of neuropeptides in echinoderm physiology and behaviour.

In order to understand how the environment, parental environment and inbreeding influence immune function and life history traits, I carried out a series of experiments using the Indian meal moth, Plodia interpunctella, as a model organism. Past studies have focused mainly on one aspect of environmental fluctuation at a time, so, to study the nature of the interactions between environmental variables in determining immunity, temperature, food quality and density were all varied together. There were interaction effects on immunity between all three environmental variables. The effect of density, for example, can be reversed if diet is changed from high- to low-quality. Diet quality has been shown to affect many life-history traits and an interesting question arising from this is whether these effects carry on to the next generation. I showed that the negative effects of a poor diet can be seen in the offspring of those affected but that a good quality diet given to the offspring goes some way to ameliorate these effects. Some of these effects on offspring could be mediated by maternal investment in their eggs; for example, when females were mated to a male that had received a poor quality diet, egg sized showed a strong effect of maternal size, with smaller females laying smaller eggs. Finally, I addressed the question of how inbreeding affects immune function using P. interpunctella derived from Australian stocks as well as a UK culture and I showed that there are some high costs to be paid in terms of larval size, egg size, larval survival, protein content of the haemolymph and immune function. There were also strong effects of origin, for example Australian males showed a very marked reduction in PO activity with inbreeding, but Australian females and both sexes from the UK lines did not show a great reduction with inbreeding.

Most organisms display circadian rhythms of approximately 24 hours in many aspects of their physiology and behaviour. The synchronization between their internal rhythm and the environmental light-dark cycles is essential for an organism’s survival and fitness. In the fruit fly, Drosophila melanogaster, circadian locomotor activity is controlled by central pacemaker neurons, in which the circadian oscillation of the molecular clock is built on the negative feedback regulation of period (per) and timeless (tim) gene expression. After transcription and translation, PER and TIM proteins form stable heterodimers in the cytoplasm and transfer into the nucleus to suppress their own transcription. Whether other processes including PER homodimerisation and nuclear trafficking are involved in circadian feedback control remains largely unknown. To study the functions of these processes, I attempted to specifically disrupt PER homodimers and nuclear export sequences (NES). I found that PER homodimers are required for PER nuclear translocation, period transcriptional repression, and normal circadian behaviour in flies. I also demonstrated that the potential NES of PER contributes to the repressor activity of PER and temperature compensation of the circadian clock. Light can phase-shift and even disrupt the molecular clock by degrading TIM. Light-dependent TIM degradation in Drosophila is mainly mediated by the photoreceptor CRYPTOCHROME (CRY). However, CRY-independent light-input pathways are also utilized by the Drosophila circadian clock. To explore these pathways, I investigated the function of a novel gene quasimodo (qsm) and found that QSM is a light-responsive protein. In constant light, qsm mutants maintain oscillation of clock proteins and show abnormal behavioral rhythms, indicating impaired photoreception. 6 Functional analysis suggests that qsm may mediate TIM degradation in the absence of CRY, and constitutes part of a novel light-input pathway to the clock. In addition, I found that in conjunction with a functional circadian clock QSM may suppress light induced ultradian rhythms.

Despite the marked deceleration in the amount of ozone lost at the poles each year, high levels of solar ultraviolet radiation (UVR) continue to reach our biosphere, potentially threatening living organisms, which owing to their life-histories and physiological constraints, are unable to avoid exposure to UVR. I aimed to demonstrate that cetaceans are affected by UVR and that they have adaptive mechanisms against exposure. Using histological analyses of skin biopsies and high-quality photographs, I characterized and quantified UVR-induced lesions in 184 blue, fin and sperm whales sampled in the Gulf of California, Mexico, and estimated indices of skin pigmentation for each individual. To examine the molecular pathways by which whales counteract UVR-induced damage, levels of expression of genes involved in genotoxic stress pathways (heat shock protein 70: HSP70, tumour protein 53: P53, and KIN protein genes: KIN) and melanogenesis (tyrosinase gene: TYR) were quantified. I not only detected evidence of sun-induced cellular and molecular damage but also showed that lesions were more prevalent in blue whales, the study species with lightest pigmentation, and sperm whales, the species that spends longest periods at the surface. Furthermore, within species, darker whales exhibited fewer lesions and more apoptotic cells, suggesting that darker pigmentation is advantageous. When accounting for interspecific differences in melanocyte abundance, sperm and blue whales presented similar amounts of melanin, although sperm whales overexpressed HSP70 and KIN. This suggests that sperm whales may have limited melanin production capacity, but have molecular responses to counteract more sustained exposure to UVR. By contrast, increased UVR in the study area led to increases in melanin concentration and melanocyte abundance of blue whales, suggesting tanning capacity in this species. My study provides insights into the mechanisms with which cetaceans respond to UVR and reveals the central role played by pigmentation and DNA-repair mechanisms in cetaceans.

Vanadium is present in natural waters predominantly as the orthovanadate anion V03/4- in concentrations of about 10⁻⁸M. Orthovanadate perfused through the gills of fresh water or sea water adapted eels induces vasoconstriction at concentrations as low as 5 x 10⁻⁸M. The pillar cells of the respiratory lamellae and the afferent and efferent blood vessels of the gill filament are affected by orthovanadate. If orthovanadate 5 x 10⁻⁸M is perfused through the gills of sea water adapted eels, the outfluxes of Na+ and Cl- are significantly reduced. Vanadium is taken up by young eels (elvers) in a manner dependent on the concentration of orthovanadate in the environment over the range 10⁻⁸-10⁻⁵M. Vanadium is deposited in the kidney, liver, bone, blood and skeletal muscle. An environmental concentration of 10⁻⁴M orthovanadate is rapidly toxic to elvers causing death within 7-26 days of exposure. Elvers loaded with vanadium through 2 months exposure to 10⁻⁵M orthovanadate show little sign of depleting their vanadium burden after 5 weeks exposure to 10⁻⁸M orthovanadate. The eel intestine is the main site of entry of vanadium into the eel, gill contributes <5% of the total uptake of orthovanadate by the eel. The influx of orthovanadate across eel intestine is dependent on the concentration of orthovanadate in the external environment. The results are discussed in relation to the published literature on the physiological and biochemical actions of vanadium and the extent to which vanadium might be an environmental hazard is assessed.

The effects of thermal environments from 20oC. to 40oC. at high and low humidities on the physiological reactions of young calves.

Telomeres, the repetitive DNA sequences that cap eukaryotic chromosomes, are thought to play an important role in linking life conditions and senescence. In vertebrate somatic cells, telomeres shorten at each cell division, and the rate at which they do so has been linked to cellular and organismal senescence. Although telomeres generally shorten with age in vertebrates, in most species studied there is considerable variation between same age individuals. In this thesis, I examined the telomere dynamics of various avian species, investigating both the causes of variation in telomere length among individuals and what effect this variation has on attributes such as survival rates. Previous studies have shown that most telomere loss occurs in young individuals and it thus makes sense that early life conditions are responsible for much of the inter-individual variation in telomere length. I investigated this idea by studying chick telomere dynamics in a wild population of lesser black-backed gulls Larus fuscus. There was considerable variation in hatching telomere length among individuals and much of this variation was related to circumstances during embryonic growth. Larger hatchlings had shorter telomere lengths, suggesting that embryonic growth rate could have affected telomere attrition. Independent of this trend, males had longer telomeres at hatching than females. Although telomere length did decrease with age post-hatching, these initial variations remained consistent during the initial post-hatching period. The relationship between early life conditions and telomere length was investigated further with a longitudinal study of telomere length in chicks of the European shag Phalacrocorax aritotelis. A previous study on this population of birds had shown that telomere length declines with age within individuals over a period of several years. However no change in telomere length was detected over a period of 11-13 days during the chick period. Body size had no effect on telomere length, but males did have longer telomere than females. These initial chapters investigate telomere length in chicks; however there are very few studies that investigate telomere length over the entire lifespan of long-lived species. I thus next examined the telomere dynamics of two species of long-lived seabird, the northern and southern giant petrels (Macronectes spp.). In both giant petrel species, telomeres were shorter in adults than chicks, but there was no trend for adult telomere length to decrease with age. In southern giant petrels, there was a significant relationship (independent of age and sex) between an individuals telomere length and whether it was still alive 8 years after it was initially sampled. This relationship was not present in northern giant petrels, possibly due to a smaller sample size. The results thus support both the idea that most telomere loss occurs in young individuals and that telomere length may be an indicator of life expectancy. Various methods exist to measure telomeres. As the number of taxa whose telomere dynamics are being studied increases, it becomes increasingly important to know which methods are the best to use and to what extent these methods are applicable across species. These questions were investigated in relation to work conducted on the telomere dynamics of the blue-footed booby Sula nebouxxi. Both the TRF and qPCR techniques were used to measure booby telomeres, but problems arose with both methods. It is possible that these problems occurred because blue-footed boobies have a particularly large amount of interstitial telomeric DNA, although a more detailed analysis of booby telomeres would be necessary to determine this. These findings suggest that standardised methods to measure telomeres cannot necessarily be applied to every new species whose telomere dynamics are studied. The evidence presented here suggests that the study of telomere dynamics can be a very powerful tool for behavioural ecologists. It now seems possible that telomeres might provide both a way of measuring the long-term costs of early life-conditions and a way to measure the quality of an individual. However, further research is still needed to fill in the considerable gaps in our knowledge and fully exploit the potential telomeres have for behavioural ecology.