The ecology and behaviour of naked mole-rats were studied for two years in Tsavo National Park (West) in Kenya, backed up by captive work on these blind colonial bathyergid rodents. 14 colonies captured contained 70-80 animals on average. In each colony. only a single breeding female reproduced, producing litters of 5-13 young year-round. Analysis of capture data and a mark-recapture programme provided evidence for a tendency towards defensive behaviour by large animals and worker behaviour by small animals. The production of mole-hills was found to be strongly associated with seasonal rainfall. One colony produced 400-500 mole-hills per year, equivalent to 3.6-4.5 tonnes of soil or 2.3-2.9 kilometres of new burrows. The digging efficiency of individuals and cooperative teams of mole-rats was found to be limited by extremely hard. dry soils, and reduced in saturated soils. 20 individuals from one colony were radio-tracked. The complete burrow system was found to be exceedingly complex and over 3 kilometres in length. Individual activity and foraging behaviour were inversely related to size. Activity levels were closely correlated with surface burrow temperatures. Most mole-rat food consisted of large. randomly distributed tubers found deep down, and small tubers in dense. well-defined and widely dispersed patches near the surface. Radio-tagged animals apparently burrowed for the large tubers and patches at random. but used area restricted searching within patches of small tubers. Predation by snakes in surface burrow networks was observed. and anti-predator behaviour of mole-rats recorded. It was concluded that Heterocephalus colonies are limited by the distribution and biomass of food resources, and the energetic and tooth-wear costs of locating them: this requires group-living. Inbreeding and kin selection in isolated groups contribute to the development of eusociality in Heterocephalus.

Vocal production: Guinea pigs (GP) are gregarious animals with a well-characterised repertoire of 11 vocalisations. These are context dependent, communicating information about danger, identity and emotional state. Vocalisations have previously been produced by electrical stimulation of three areas in the GP brain: anterior cingulate, hypothalamus and periaqueductal grey. These vocalisations were reported as natural-sounding, but with little or no spectral analysis to support this assertion. I elicited calls from urethane-anaesthetised GP by stimulating all the above areas, and from the amygdala and several thalamic nuclei. The spectrotemporal properties of these vocalisations were analysed and eight distinct vocal patterns were identified. For comparison, recordings of spontaneous calls from the same colony (Grimsley et al., 2012) were analysed in the same way, then used to name the electrically elicited calls. For six call types the matches between electrically elicited and spontaneous calls were unambiguous. The remaining two elicited calls were identified as being slightly unnatural versions of one spontaneous call. Five calls were produced during the (1.6 s) electrical stimulation and three were produced after the stimulation, lasting up to 30 s. Concurrent bilateral stimulation of loci producing post-stimulus calls always had an additive effect, whereas stimulation of two loci giving during-stimulus calls was more complex. Auditory representation of vocalisations: To date, eight functional areas of GP auditory cortex have been identified using electrophysiology, and their responses to vocalisations has been investigated previously. I have discovered a new area, ventral to those currently described, which was named deep ventrorostral belt (dVRB). It is unresponsive to a broad range of puretone auditory stimuli, yet is highly selective to conspecific vocalisations. Single neuron recordings were taken from dVRB and the primary auditory region (AI) during the audio-vocal study. Audio-vocal interactions: The vocal production system communicates the expected sensory consequences of its action. This allows the auditory system to discriminate between self-produced and external sounds. These sensorimotor connections originate in premotor areas of the midbrain as well as motor planning areas of neo- and paleocortex. The basal amygdala (BA) – an emotion-mediating structure – yields vocalisations in GP when stimulated, and is involved in the affective prosody of human speech. It was hypothesised, therefore, that BA would also have an audio-vocal role. A protocol was developed to combine electrical stimulation in BA with auditory presentation of a range of GP vocalisations, whilst recording neural activity in AI and dVRB. In both cortical areas, single-neuron responses demonstrated a complex interaction of electrical and auditory stimuli; showing both enhanced or suppressed responses, depending on call type.

As anthropogenic factors have threaten species worldwide, conservation of a species through ex situ (i. e. captive breeding, reintroduction) provides one of the most powerful tools for species conservation. However, baseline genetic data prior to reintroduction of captive-bred individuals is essential for guiding such efforts, but this has not been gathered previously in the common dormouse, Muscardinus avellanarius. Thus, this thesis provides the first comprehensive study of spatial and temporal patterns of genetic diversity of populations of M. avellanarius in UK, with specific reference to investigate the breeding structure and contemporary and historical patterns of gene flow, both in natural and reintroduced populations. Additionally, this thesis analysed patterns of variation at two regions of mitochondrial DNA (mtDNA) to broader geographic divergence among UK populations of M avellanarius. The main findings in this thesis are: (1) reproductive behaviour of reintroduced M avellanarius population was retained as in the wild population despite enforced bottleneck during captivity that could change behaviour of a species, (2) both ecological and molecular genetic data provide broadly congruent estimates about the dispersal characteristics of M avellanarius in a large, continuous habitat. A significant isolation-by-distance (IBD) pattern at a fine scale (less than 1 km) was apparent within continuous populations with males more mobile than females (male-biased dispersal), (3) gene flow was generally restricted among separate populations (i. e. between habitat patches) at a scale of 1-10 km, (4) using mtDNA sequence data, three divergent phylogenetic lineages (Northwestern, Central and Southern) were recognized in the UK, implying colonization of the UK from separate refugia (e. g. continental Europe), that probably diverged during the Pleistocene period but prior to the last Ice Age. Interestingly, genealogical evidence revealed that the source populations of captive bred M avellanarius that were released in Wych (northern England) are from the southern UK, thus highlighting the use of genetics for conservation. The results of these studies will not only contribute to the understanding of dispersal characteristics and how this process has structured the populations at small and large scales, but also add significantly to biological and evolutionary understanding on M avellanarius, which can be directly applied to the ongoing conservation and management of this species.

No description available.

No description available.

Three series of experiments are described. In the first two, young female mice of the T.O. strain were exposed before weaning to the indirect physical presence of 12 adult males, 12 adult females or, in the control group, to the absence of any adult conspecifics other than the mother. It was found that young female mice exposed to adult males developed more rapidly than mice in the other two groups. They weighed more, physical features of development such as the opening of the auditory canal and of the eyes occurred earlier and this difference in the pace of development was also reflected in the ages at which certain reflexes and early responses developed and then dropped out of the animal's repertoire, Females exposed to adult males became sexually mature at an earlier age, bore litters earlier and were also found to be more active in an open field when tested as adults. In the third study, young female mice were exposed to the odours of soiled sawdust from cages housing 12 adult males or 12 adult females. Control groups were exposed to; odours from clean damp sawdust. In this study the behaviour of the mothers was also investigated but no clear-cut differences were found between treatment groups which would indicate that the effects are more likely to be directly on the young. This time no consistent differences in weight were found between the mice in the different treatment groups and few differences in the ages at which developmental features occurred. Differences were found, however, in activity and in sexual development, The young female mice exposed to odours of adult males were more active than the mice in the other treatment groups tooth at 21 days of age and when tested in an open field as adults. They also matured sexually earlier, bore their litters at an earlier age and reared pups which were heavier at weaning. It would appear, therefore, that at least some of the effects oh development and behaviour can be produced in response to olfactory cues although the effects are greater when physical contact between young females and adults is possible, even if this is only indirect. These effects are not immediate, becoming manifest towards the end of the second week of life but do appear to be long lasting.

The maintenance of genetic variation is a general conservation concern for endangered species, such as the British hazel dormouse (Muscardinus avellanarius). The structuring of genetic variation at multiple hierarchical levels, from individual through to the total population, can provide insights into within-population processes, such as inbreeding and social behaviour, and help understand the causes of population partitioning, both current and historical. Investigating the processes that shape and alter levels of genetic variation within hazel dormouse populations will highlight any factors that may influence their continued persistence and inform on appropriate management strategies. The current thesis aimed to address whether a) microbial-mediated odour could be a mechanism for kin discrimination, inbreeding avoidance and social cooperation; b) the hazel dormouse displays social structuring and, as a result, evidence for inbreeding avoidance; c) there is within and among population structuring, resulting from identified physical features that restrict gene flow and d) current patterns of genetic variation inform us about historic dispersal. Captive bred individuals of known pedigree were used to assess the relationship between bacterial community composition and relatedness. Microsatellite markers were used to generate relatedness estimates and analyse levels of genetic variation at the individual, social group and sub-population levels on samples obtained from Sussex and the Isle of Wight. Mitochondrial markers were used to infer patterns of genetic variation at the total population level, including samples obtained from all over the species range. F-statistics were then used to infer any deviations from Hardy-Weinberg equilibrium that could imply for example inbreeding or gene flow. The main findings of the thesis are that 1) microbial composition correlates with genetic relatedness in the hazel dormouse, indicating that microbial-mediated odour could be a mechanism for kin discrimination; 2) inbreeding levels are not significantly high, even though both male and female close relatives are in close proximity, with neither sex exclusively practising natal philopatry or dispersal; 3) no identified habitat features appeared to influence gene flow and levels of genetic variation did not differ between sites, regardless of the habitat features; 4) on the basis of mtDNA, the British dormouse population is likely to have been founded by a relatively recent colonisation event, rather than be a remnant of a more ancient indigenous species. The results of this study contribute to our understanding of how social and dispersal mechanisms determine a population’s composition and hence provide some indicators of how the species has evolved. It is intended that knowledge of the species’ social structure and, in particular, details of their inbreeding avoidance behaviour and tolerance of close relatives, will help optimise population survival in future reintroduction programs.

No description available.

The energy assimilated by a small population of Arvicola terrestris amphibius (L.) occupying a 380m stretch of stream in south Durham was calculated by quantifying the parameters of population respiration and tissue production and was subsequently related to the available food supply. The changes in population density, size and age structure were monitored by frequent live-trapping over the entire calendar year and an assessment was made of the population structure and tissue production over consecutive periods of twenty days. The temperature - and above-ground activity experience of representatives of the population were investigated implementing artificial burrow systems built into outdoor enclosures under simulated stream conditions. The pattern of day to day activity was monitored by recording thermo graphs which registered the temperature changes in vole nests caused by the intermittent presence of the animal's body heat. Nest chamber and soil surface temperatures were recorded concurrently. The patterns of vole activity were analysed and related to conditions of social inter-reaction and to variations in weather parameters. The oxygen consumption of representative members of the population was investigated at a range of experimental temperature during periods of both rest and activity by means of a closed-circuit respirometer. The population respiration demand was estimated over consecutive periods of 20 days with corrections included for the seasonal variation in population size and age structure, ambient temperature and the proportion and quality of above-ground activity. The available food supply was estimated by regular sampling of the vegetation within the feeding range in conjunction with an investigation of the rate of plant decomposition. The feeding preferences of the population were examined and the energy flow between primary and secondary production deduced.

No description available.