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This thesis investigated behaviour and behavioural phenotypes in the Mucopolysaccharide (MPS) disorders. The MPS disorders are a group of rare lysosomal storage disorders which are characterised by a period of normal development followed by gradual cognitive and/or physical decline.Paper 1 describes a systematic review of the extant literature on cognitive, motor, social, linguistic and behavioural presentation in all of the MPS disorders. 25 papers were reviewed and the methodology they employed was assessed. Sleep disturbance was found to be part of the behavioural phenotype of MPS III. In MPS I and II fearfulness and sleep problems occurred in most cases. In MPS II participants with the mild form were found to have relatively normal development and few or no behavioural problems, while those with the severe form had behavioural problems, delayed speech, delayed development and limited motor function. High rates of challenging behaviour, most commonly associated with aggression, hyperactivity, orality, unusual affect and temper tantrums were consistently observed in children with MPS III.Paper 2 describes an empirical study investigating the behavioural phenotype of MPS III, Sanfilippo syndrome. Parents of 20 children with MPS III, 5 adults with MPS III and 25 children with Intellectual Disability (ID) completed questionnaires relating to their son/daughter’s behaviour and adaptive skills. The frequency of challenging behaviours displayed by children aged 2-9 years with MPS III and ID were high but not significantly different. Behaviours associated with hyperactivity, orality, body movements and inattention were seen significantly more frequently in 2-9 year olds with MPS III than ID. The frequency of challenging behaviours displayed by children with MPS III and their adaptive skills was found to decrease with age. Children age 10-15 years with MPS III displayed significantly fewer problem behaviours than children of the same age with ID. It is recommended that parents with a child with MPS III aged 2-9 years are offered clinical services to support them with managing challenging behaviour while those with a child of 10 years or over are offered support with managing health concerns and end of life care.The third Paper, provides an evaluation of the strengths and limitations of the literature review and the empirical study. The findings and clinical implications from both studies are discussed. The process of conducting research into rare, life limiting, genetic syndromes is reflected upon and recommendations for replication and further research are made.

We investigated the behavioural mechanism underlying the recently discovered latitudinal variation in the social structure of the spider Anelosimus studiosus through population censuses, behavioural interaction trials, reciprocal nest transplants to different temperature environments and breeding experiments. Nest censuses completed at replicated sites at 2° changes in latitude between south Florida (26°) and east Tennessee (36°) indicated that the dominant social structure is a solitary female nest. Multifemale nests consisting of cooperative females and their young first appeared in the populations at 30° latitude and increased in frequency of representation with further increases in latitude as did number of females within multifemale nests. Interaction trials showed that communication and physical contact underlie the two social structures. Females from solitary female nests and F1 offspring reared in the laboratory demanded space (asocial phenotype), whereas individuals of multifemale nest origin (from same and foreign nests) were attracted to one another (social phenotype). Field experiments further showed that (1) individuals that dispersed from multifemale nests dispersed shorter distances and (2) nest coalescence was observed only at the higher latitudes, coincident with the presence of multifemale nests. Habitat transplants suggested that the behaviour underlying social structure is not plastic in this system, and breeding experiments eliminated a cryptic species alternative to the presence of different social structure phenotypes. Although both asocial and social phenotypes were present at all latitudes, the frequency of the social phenotype was rare at lower latitudes.