Previous work has shown that reproductive success in the blue tit (Parus caeruleus) is largely environmentally determined. In this thesis I explore the roles of human disturbance. habitat quality and parental quality as environmental components of reproductiv~ success. measured in terms of lay date. clutch size, number of offspring fledged and body condition of offspring. I start by quantifying the effects of human disturbance on vocal defence behaviour and reproductive success. -My results show. that blue tits increase their investment in vocal oefence as their chicks age. and quickly become habituated to human disturbance. I found no evidence that reproductive success was significantly related to human disturbance or investment in vocal defence. I then investigate the relative effects of habitat quality and parental quality at the territory level on reproductive success. The prevalence of oaks. the preferred host of the primary food source for breeding blue tits. within estimated territories is measured and relationships with reproductive success explored.. The number of oaks within a blue tit territory is positively associated with reproductive success. leading to advancement of lay date. increased clutch size and greater fledging success. Body condition of offspring. however. is not related to habitat quality. but instead is positively associated with the body condition of both the male and female parents. The mechanism.behind .these relationships are then further examined using data on the phenology of individual oaks in a breeding territory. I found that -oak phenology is a significant determinant of chick condition and survival and that. where blue tits mis-time their reproduction relative the phenology of the oaks. fecundity is reduced. Lastly. I discuss the implications-of my findings in the context of environmental change. and identify..possible directions for future research.

In multicellular organisms, the differentiation program of a group of cells can be conceived of as a sequence· of developmental processes including induction, cell fate acquisition, patterning, cell death and morphogenetic movements. These processes are inter-dependent and need to be coordinated during embryogenesis. Eya and Six genes code for transcription factors that act together in a transcriptional complex. Both factors are required for the differentiation of distinct embryqnic structures such as the kidneys, pituitary gland and inner ear; in humans, mutations in EYAl or SIXl can cause Branchio-ato-Renal syndrome, characterised by otic, branchial arch and kidney defects. In the zebrafish, at 24 hpf, eyal and sixl are expressed in ventral otic epithelium, and interestingly the dog-eared/ eyar j- zebrafish mutant shows a characteristic misshapen ear at this stage: an elongated ·otic vesicle with a thicker dorsal epithelium in comparison to the wildtype. This observation suggests that eyal plays a role during the first !4 hours of otic development. Our results suggest that Eya! is not required for otic induction, and that, functions independently of previously characterised otic induction pathways. Instead, Eya! is required for acquisition of a correct morphology and for refinement of patterning within the otic vesicle as revealed by the expression of tbxl, otxl, pax2a, and snai/2. Eya! also plays a role in the neurogenic program giving rise to the statoacoustic ganglion. We showed that eyal function has a noncell autonomous effect in the regulation of tbxl otic expression. sixl zebrafish morphants phenocopy some of these aspects, such as the dorsal thickening of the otic vesicle at 24hpf, and the mispatterning of certain regions of the otic epithelium, but they also show some additional defects such as a somite phenotype. Nevertheless, six1 morphant otic phenotype is not identical to that of dogeared/ eyal mutant. The data from genetic interactions suggests that eyal genetically acts parallel to six1.

A fundamental variable in cooperative breeding animal species is the degree to which reproduction is partitioned among group members - termed reproductive skew. Understanding the causes for variation in skew contributes to our understanding of social evolution because skew directly impacts on the inclusive fitness gained through cooperation. In this thesis I present a novel model system for investigating skew, by providing detailed sociogenetic data to show a polymorphism in colony social organisation in a species of ant, Leptothorax acervorum. In multiple queen colonies queens reproduce relatively evenly in most populations (polygyny), but I show that skew is particularly high in a Spanish and Japanese population where just one queen out of many monopolises all reproduction (functional monogyny). I further investigated how high skew among queens was maintained in the functionally monogynous Spanish population by undertaking behavioural observations and experiments. In contrast to what is assumed by the majority of skew theory - that control lies with individuals in direct competition over reproduction (queens) - I show that a third party (the workers) plays a principle role in determining which queen reproduces in the colony. Genetic analyses also revealed that workers favour the queen who meets their fitness interest, showing that workers posses both the information and power for their interests to prevail. Furthermore, such worker influence is not observed in polygynous colonies and tellingly multiple queens reproduce. Functional monogyny maintains high relatedness and therefore high indirect fitness benefits among colony members, yet polygyny reduces such benefits because of multiple genetic lineages within the colony. Polygyny is therefore seemingly paradoxical when only considering relatedness, so presumably other parameters are important. Icompared life-history traits and ecological factors associated with each social organisation and discuss the potential importance of habitat patchiness, limited dispersal and queen turnover in shaping the marked contrast in skew between populations. Furthermore, I detected high levels of triploid females in the functionally monogynous populations supporting a high frequency of matched matings between sexuals at the complementary sex determination locus. Importantly, there have been no reports of triploidy in polygynous populations showing that variation in social organisation, along with associated life-history traits and ecological factors, can determine the frequency of matched matings and increase the risk of genetic load. The research presented in this thesis overall highlights two important issues: first,the basic assumptions of skew theory must be tested if skew models are to be applicable,and the gap which has developed between skew theory and associated empirical testingneeds to be bridged. Second, we cannot focus on relatedness alone to explain skew or test kin selection theory, because factors within an ecological parameter are also fundamental.

Nereis acuminata is a polychaete species with a unique life cycle. A male and female form a monogamous pair bond, the female lays eggs and dies. The male then fertilises the egg and undertakes sole parental care until the eggs hatch and larvae leave the parental burrow; the male can then reproduce again. This body of work investigated aggression, pair formation, filial cannibalism, the scent of experience and the occurrence of male parental care for eggs fertilised by another male in the polychaete species Nereis acuminata.Female aggression following egg release was found to be absent when the females were not in the presence of an egg mass, with no aggression displayed towards sexually mature females. Aggression between two males did not have a subsequent effect on the pairing behaviour with a female, although there was slight decrease (not significant) in the time taken for individuals to pair if they had previously formed a pair bond. Males that had previously had an aggressive encounter were fought subsequently to determine if there was recognition for previous opponent but aggression did not change following previous fights, indicating that previous fights between the same opponents does not have an effect on the aggression levels exhibited. Aggression between the populations maintained in the laboratory, Reish (R), Newport (N), San Gabriel (SG), Connecticut (C) and the wild population Los Angeles (LA) were examined. Although there were significant differences in male aggression between the R, N, SG and C populations, and significant differences in female aggression between the R and LA populations, aggressive behaviour was not found to be a strong indicator of population divergence. Observations of pair formation, however, provided a stronger indicator of divergence. Pairing behaviour within each population was found to be significantly different to that between individuals from different populations, with Connecticut individuals failing in the majority of cases to form a pair bond with any of the other three laboratory populations. The LA and R populations, sampled in the same location 44 years apart, did not form pairs with the same frequency as males and females from the same population but interactions between R and LA males and females were found to form a high frequency of pairs, indicating that although the R population may be heavily inbred, females of this population will still form monogamous pairs with males from the LA population. The behavioural and molecular evidence suggests that these populations form a species complex and this is important to note when undertaking ecotoxicology testing as the different populations may respond differently to the same environmental conditions.The occurrence of filial cannibalism was investigated in male N. acuminata, looking at aggressive interactions between males and female mate choice. The presence of a cannibalistic male did not affect the aggression observed between two individuals and it appeared that females could not discriminate between males that had cannibalised their egg mass. Conditioned water was used from various sources to determine if female preference could be altered following an initial selection of male by the female. Water from males caring for eggs and from new experienced males that had just completed egg care was found to change the choice of the female to a pre-treatment loser. Water conditioned from females, juveniles and inexperienced males appeared to enforce the previous choice of the female as in these trials the female chose the previous winner more frequently. The mechanisms related to the scent of experience in terms of physiology and release of the chemical signal however, are still unknown. It is thought that there is a physiological change in the male, for example by release of sperm or by production of ‘new’ sperm that the female can detect and uses to indicate that a male has previously cared for a brood. As the female dies following egg release and the male undertakes sole parental care, an honest indication of the ability of the male to successfully care for eggs is vitally important.Finally, male behaviour towards an egg mass fertilised by another male was investigated. Inexperienced males that had not completed egg care were found to care for the eggs until they hatched whereas experienced males were not, instead cannibalising the egg mass. Inexperienced males were likely to gain from adopting eggs by gaining parental experience and receiving more matings in the future. Experienced males did not gain benefits from caring for unrelated eggs but cannibalising the eggs would benefit the experienced male by providing extra nutrients.Nereis acuminata is an ideal species to use as a model organism to investigate the behavioural and evolutionary processes involved in mate choice, aggression, preference for parental experience and the chemical signalling involved, due to its adaptable life history, short life cycle and ease of maintenance in the laboratory.

Pacifastacus leniusculus and Procambarus clarkii are highly invasive freshwater crayfish and are having detrimental impacts on native species and habitats throughout Europe. The application of pheromone baits have been proposed as a way of increasing trap efficiency for population control, however the chemical identity of crayfish pheromones is unknown. An incomplete understanding of chemical communication has delayed progress in the development of appropriate bioassays. This thesis therefore focused on researching the natural context of chemical signalling by crayfish, including signal delivery and receiver response. Urine release by male and female crayfish was found to coincide with aggressive behaviours rather than reproductive behaviours. Female urine release was essential for initiating mating, with males detecting female receptivity by spying on hormones and metabolites released with threat signals. Physiological indicators of reception included a brief cardiac and ventilatory arrest followed by an increase in rate. Both behavioural and physiological responses formed the basis of a novel assay design. During courtship male crayfish do not appear to advertise by urine signals. This raised the question of whether chemical signals were important for female assessment of the quality of size-matched males. When given a free choice, females could not distinguish dominant and subordinate males through chemical signals alone. This suggests that females either use other criteria (e.g. size) for mate choice or perform cryptic postcopulatory mate choice. Blocking natural urine release of crayfish, which had previously fought to establish dominance, and artificially introducing urinary signals proved an effective bioassay for investigating the mechanisms of dominance hierarchy formation. Urine from the dominant male was the key factor in establishing dominance relationships. In the absence of dominant urine, subordinate males were less likely to retreat from aggressive bouts and fights were more intense. The mechanisms of signal delivery during agonistic encounters were investigated by measuring ventilatory activity. Increased ventilation rate was associated with highly aggressive behaviours and urinary signalling. This indicated crayfish create gill currents to disperse signals and increase transfer efficiency from sender to receiver. This thesis sheds light into the mechanism of chemical communication in crayfish and provides the basis for future bioassay guided purification of crayfish pheromones.

The relationship between male aggressive behaviour and population variables in the bank vole (Clethrionomys glareolus (Schreber, 1730)) was studied using two large (550m2) field enclosures. Known populations were established in each of the enclosures, and followed by live trapping. In an attempt to manipulate the level of aggressive behaviour in one (the experimental) enclosure with respect to the other (the control) a majority of the founding males in the experimental enclosure were castrated. Laboratory arena testing was used to study the behaviour of adult, castrated and immature male voles. It was demonstrated that both castrated and immature male voles were significantly less aggressive than adult males. Adult males were found to fight less with castrated and immature males than with other adults. Castrated males sometimes exhibited retaliatory behaviour when approached by either an adult or immature male, but overt aggressive behaviour rarely resulted. Immature males were very rarely aggressive. Observation of behavioural interactions in the field (at a bait point) showed them to be qualitatively different to those observed in the laboratory arena; voles appeared very wary of each other, and many interactions observed were characterised by mutual avoidance or flight. Oveitaggressive behaviour was rarely seen. It can be inferred that voles do fight in the field, because they commonly exhibit small wounds on rump, tail, and face; these could however, be sustained in the confinement of burrows, where escape and mutual avoidance are less possible than at a bait point, and which may be more closely paralleled by the laboratory arena. Significantly more adult males in the enclosures showed fresh wounds than did castrated or immature males, or adult or immature females. The number of voles in the experimental enclosure increased significantly faster than did the number in the control enclosure; the density in both enclosures was also significantly higher than commonly encountered in the wild. The difference in numbers between the two enclosures was due to a difference in the number of immature animals entering the trappable population; mortality of marked animals in both enclosures was very slight but mortality of infants was significantly higher in the control enclosure than in the experimental. Reproductive inhibition of adult and immature animals of both sexes was observed in both enclosures. At the same time, extremely young animals trapped in the wild populations were found to be sexually mature. The differences in the use of space by different age and sex classes between the two enclosures were also investigated. The study demonstrated that male aggressive behaviour had a significant effect on the population variables of bank voles at the high densities and at the high rates of population growth observed in large enclosures. The findings are discussed in the light of several hypotheses put forward to explain population regulation and cyclic changes in numbers of Microtine rodents.

Vocalizations of the largely nocturnal Japanese Brown Hawk Owl Ninox scutulata japonica were studied, with particular reference to the function of vocal communication. The adult owls were found to have thirteen types of vocalization and three non-vocal sounds with the possible addition of one other vocal sound. Nestlings had four vocal and one non-vocal sound. The development of the vocal repertoire was also studied from captive juveniles. Most of the vocal repertoire was recorded and sonagraphically analysed, and their behavioural contexts were investigated to give an idea of their various functions. The main function of primary calls was in interactions with conspecific birds from a distance. The daily calling of territorial males was not time-related and appeared to be greatly influenced by the intraspecific environment. Seasonal production was concentrated during breeding activity, showing four peaks which are discussed in terms of territorial, sexual and family interactions. The unusual vocal activity of a replacing male was studied and gave valuable additional information. Primary calls were also considered to convey different types of information through variation in their physical structure. From the examination of calls in natural conditions and in aggressive responses to playback, variations of frequency and rate were related to location in the territory, the breeding cycle and the caller's motivational state. There were consistent individual variations in temporal and frequency features of the calls. Playback of neighbour and stranger's calls and that of the mate and other females' calls at various locations in the territory elicited differential responses, suggesting individual recognition by voice. A general description of the species, including their classification, distribution, migration and inter-racial differences, is also given.

The reproductive biology of three strains of Callosobruchus maculatus F. (Coleoptera: Bruchidae), the cowpea-seed beetle, was studied. This beetle is a serious pest of stored legume seeds in the semi-arid tropics. As females aged, energy reserves were depleted and aspects of this decline were related to the number of eggs laid in order to explain the observed daily egg laying pattern of C. macuiatus. Various factors affected the fecundity of females. The initial adult weight of females showed a strong positive relationship with the number of eggs laid. Substances, which could be extracted from cowpeas, were shown to be necessary to allow normal oviposition on an artificial substrate, glass beads. The male contribution to female fecundity was also investigated. Approximately half of the study was concerned with factors which govern a female's choice of oviposition site. The presence of a pheromone which enabled females to distribute their eggs more efficiently among cowpeas was demonstrated. This demonstration necessitated the development of a bioassay using a choice chamber which allowed beetles to choose between cowpeas marked with pheromone and control cowpeas. Using the bioassay, the solubility of the pheromone in different solvents was examined. The persistence of the pheromone over different periods of time was investigated and it was shown that the pheromone can remain active for at least thirty days. In addition to the marking pheromone, the role of physical characteristics of the oviposition substrates was also studied. The surface area and weight of such substrates were shown to affect the choice of oviposition site by females. The results obtained are discussed in the context of previous work on bruchids, particularly models of oviposition behaviour proposed by some workers.

Agonistic activities, that is behaviours associated with aggression and defence were studied in Carcinus maenas. Two particular agonistic interactions which employ the chelipeds were chosen for detailed analysis; the fast strike and threat display behaviours. The fast strike involves rapid flexion of the chelipeds and is completed within 30 to 60 ms. The limb is propelled forwards and downwards from the first two cheliped joints. Calculation of the energy required for a strike revealed that it is necessary for the muscles of the coxa--basi-ischium complex to develop energy before the strike is performed. It is found that this energy is produced by antagonistic muscles contracting together before the strike, allowing isometric tension development. The moments of the coxa promotor and remotor muscles about the thorax-coxa joint give rise to a bistable articulation in which the coxa may be rapidly remoted or promoted in a "flip-flop"? situation. Three of the basi-ischium muscles, the Anterior levator, Anterior and Posterior depressors, have an unusual geometry which gives them more than one function. The contributions of the coxal and basi-ischium muscles during the strike is discussed and a method by which the strike is performed, is suggested. A strike only occurs from a threat display position in which the chelipeds are extended and levated. The threat behaviour was examined to determine the muscle activity which precedes the strike. Characteristic patterns of motor activity correspond to different postures of threat display. Manipulating various stimulus parameters presented to the crab showed that threat displays are most readily released by the rapid approach of large objects. Neural activity recorded from the circumoesophageal connective nerves revealed that the presentation of stimuli representing rapidly approaching objects accompanies high frequency bursts of large spikes. This activity also corresponded to high frequency motor activity in the cheliped muscles which accompanies the adoption of extreme threat display positions.

Sedentary species face a trade-off between the advantages of exploiting food close to their homes and the cost of defending it. Consequently, the net benefit of this lifestyle may be greatest at intermediate productivity. In aquatic systems, it has been suggested that some sedentary grazers can increase the range of circumstances under which they are able to compete with mobile grazers by enhancing food resources within their feeding territories through 'gardening'. This was examined for the retreat-building sedentary larvae of the caddis Tinodes waeneri, which are often dominant in the littoral of lakes. The hypotheses tested were 1) T. waeneri gardens by fertilising its retreat (a fixed 'gallery' on which periphyton grows), and 2) gardening will be more important in lower productivity lakes. Detailed field sampling across a lake productivity gradient was coupled with a laboratory mesocosm study. A natural abundance stable isotope technique was developed to identify gardening. A survey of six populations in the English Lake District indicated that larvae garden as they fertilise gallery biofilm with excreted nitrogen and feed on their galleries. Galleries also contained more food than the epilithon and larval assimilation of galleries was related to food availability. Galleries contained a higher proportion of diatoms than the epilithon, and gallery diatom communities were associated with higher nutrient levels, especially in the lower productivity lakes. Gardening also occurred in the experimental mesocosms. Furthermore, the amount of gardening was related to nutrient levels; more gardening occurred at low nutrients than at high nutrients. Thus, 'gardening' is widespread in T. waeneri populations and may allow this species to be successful in low resource environments. It may also substantially affect ecosystem processes within the littoral of lakes by influencing patterns of nitrogen retention and enhancing overall productivity.