The structure and organization of the spatial memory system of Clark's nutcrackers (Nucifraga columbiana) were examined using three different experimental paradigms. The natural history of Clark's nutcrackers implies that they are capable of processing large amounts of spatial information accurately. In Experiments 1 and 2, Clark's nutcrackers were tested for their ability to access spatial information using both stay and shift response strategies in an operant test of spatial memory. Not only were Clark's nutcrackers capable of using the two different response strategies equally well, but subtle differences were discovered in how birds using each strategy coded spatial information into memory. Stay birds appeared to remember serial components from the list of to-be-remembered spatial locations. The spatial configuration of the to-be-remembered spatial locations played more of a role in the ability of shift birds to remember spatial locations. In Experiment 3, a naturalistic study examining the role landmarks play in accurate site identification, Clark's nutcrackers relied heavily on tall ($>$.5m) landmarks and landmarks proximal ($<$.5m) to the to-be-located site. Nutcrackers were also flexible in which landmarks they could use as cues to locate a position in space. Nutcrackers were capable of using separate subsets of a larger configuration of landmarks around a to-be-located site in order to accurately locate the site. In Experiment 4, the area of the brain responsible for spatial information processing (hippocampal complex) was measured in Clark's nutcrackers and three related corvids that are less dependent on stores in the wild. Clark's nutcrackers were found to have a larger hippocampal complex than the other three species. All four experiments support the premise that Clark's nutcrackers are capable of processing spatial information both flexibly and rapidly.

Antibiotic resistance is generally associated with a cost in terms of reduced competitive fitness in the absence of antibiotics. Despite this 'cost of resistance', the cessation of antibiotic treatment does not result in significant reductions in the prevalence of resistance. The maintenance of resistance, in spite of the costs, has been attributed to the rarity of reversion mutations, relative to compensatory mutations at other loci in the genome. However, the large size of bacteria populations, and the potential for migration, suggest that reversion mutations should occasionally be introduced to resistant populations. In this thesis, I show that additional mechanisms can prevent fixation of reversion mutations even if they do occur. Using an experimental evolution approach, with rifampicin resistance in Pseudomonas aeruginosa as a model system, I measured the costs of resistance in several environments and followed the adaptive dynamics of resistant populations where a sensitive lineage had invaded by migration. The results suggest that several additional mechanisms contribute to the maintenance of antibiotic resistance. Most rifampicin resistance mutations are not unconditionally costly in all environments, suggesting that migration between environments could maintain a resistant reservoir population. In environments where resistance is initially costly, the fixation of a revertant is not guaranteed, even if introduced through migration. Revertant fixation was impeded or prevented by clonal interference from adaptation in the resistant strain. Revertants that did successfully replace the resistant strain were forced to adapt to do so. Contrary to assumptions in the existing literature, fitness in the resistant strains was not recovered by general compensatory mutations, but instead by adaptive mutations specific to the environment. The data challenge several assumptions about the maintenance of antibiotic resistance: that resistance mutations are always costly, that the rarity of back mutations prevents the reversion of resistance, and that resistant strains recover fitness by compensatory mutations.

Mammotropes were successfully identified in the anterior pituitary gland of Miniopterus schreibersii using immunocytochemical (ICC) staining at the light and electron microscopy level. Mammotropes were distributed throughout the gland, were polygonal in shape and during secretory activity contained numerous large secretory granules (350 - 800nm). Using double ICC labelling, prolactin and growth hormone were never co-localiszed and found in individual cells only. Plasma prolactin levels were successfully measured on a monthly basis using radioimmunoassay and monthly pituitary prolactin levels were quantified using morphometric analysis of immunogold ICC staining and densitometry with polyacrylamide gels. Seasonal changes in the ultrastructure of mammotropes, and pituitary and plasma prolactin concentrations in female Miniopterus schreibersii indicated that there was an increase in prolactin secretion during the second half of the period of delayed implantation and that prolactin secretion remained elevated during normal embryonic development and lactation. This suggests that prolactin may be part of the luteotropic and lactogenic complex, and that the hormone might be responsible for terminating the period of delayed implantation. The latter is supported by experiments, where exogenous prolactin initiated precocious implantation during early delayed implantation, and treatment with bromocryptine (which inhibits prolactin synthesis) retarded implantation. Activation of mammotropes to synthesise prolactin and an increase of plasma prolactin levels occurred shortly after the winter solstice (21 June), suggesting that increasing daylength may be the environmental cue, which terminates the period of delayed implantation in Miniopterus schreibersii.

Whilst there has been a recent increase in interest in using positive reinforcement training for laboratory-housed primates, there remains a reluctance to put into practice training programmes. Much of this reticence seems to stem from lack of expertise in the running of training programmes, and a perception that training requires a large time investment, with concurrent staff costs. The aim of this thesis was to provide practical recommendations for the use of training programmes in laboratories, providing primate users and carestaff with background information needed to successfully implement training programmes whilst improving the welfare of the animals in their care. Training was carried out with two species, cynomolgus macaques (Macaca fascicularis) and common marmosets (Callithrix jacchus) in three different research laboratories to ensure practicability was as wide ranging as possible. Training success and the time investment required were closely related to the primate's temperament, most notably an individual's willingness to interact with humans, in both common marmosets and cynomolgus macaques. Age and sex however had no effect on an individual's trainability. The training of common marmosets was more successful than that with cynomolgus macaques, possibly due to differences in early experience and socialisation. Positive reinforcement training helped both species to cope with the stress of cage change or cleaning, with the monkeys showing less anxiety-related behaviour following the training programme than before. Involving two trainers in the training process did not affect the speed at which common marmosets learned to cooperate with transport box training, but behavioural observations showed that initial training sessions with a new trainer led to animals experiencing some anxiety. This however was relatively transient. Whilst the training of common marmosets to cooperate with hand capture was possible, there seemed little benefit in doing so as the monkeys did not show a reduced behavioural or physiological stress response to trained capture as compared to hand capture prior to training. However strong evidence was found that following both training and positive human interactions the marmosets coped better with capture and stress was reduced. It is recommended that an increased use of early socialisation would benefit laboratory-housed primates, and would also help improve the success of training. Further, the time investment required shows that training is practicable in the laboratory for both species, and that positive reinforcement training is an important way of improving their welfare likely through reducing boredom and fear.