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The decline in biodiversity over the last decade has motivated researchers to investigate the relationship between species richness (biodiversity) and ecosystem function. Empirical approaches are becoming more realistic as more factors have been included. Spatial heterogeneity is an example. Heterogeneity is an inherent part of the environment and apparent in all habitat types creating a patchy, mosaic of natural landscape. Researchers have reported the extent of heterogeneity in the landscape, but surprisingly not yet included heterogeneity into biodiversity and ecosystem function (BEF) studies. In recent years, empirical studies of marine systems have enhanced the BEF debate. Depauperate estuarine systems are ideal candidates for establishing model systems. In this study, estuarine microphytobenthos (MPB) were used as a response variable since the relationship between MPB and primary productivity is well-known. This relationship was exploited to employ MPB biomass as a proxy for primary productivity. Benthic chambers were used to assess the effect of macrofauna in single species and multi-species treatments on both ecosystem function and net macrofaunal movement. Heterogeneity was created through enriching sediment ‘patches’ with Enteromorpha intestinalis, providing areas of high and low nutrient. Heterogeneity, macrofaunal biomass, species richness, species diversity and flow were all varied in order to assess combined effects on the functioning of the system. Heterogeneity was found to have a significant influence on ecosystem functioning and on macrofaunal movement, however, patch arrangement did not. MPB biomass was highest in patches containing organic enrichment suggesting that nutrients were obtained locally from the sediment/water interface rather than the water column. There was variation in MPB biomass with macrofaunal species, probably resulting from differences in behavioural traits. It was also evident that flow altered species behaviour, as there was a significant difference between static and flow treatments. This work shows the importance of heterogeneity for BEF relationships.

Despite over a century of research, malaria parasites (Plasmodium) still remain a major cause of mortality and morbidity worldwide. In recent years, the application of theoretical principles from ecology and evolutionary biology to the study of these parasites has started to provide insight into variety of fundamental subjects from the evolution of virulence to the facultative strategies (i.e. phenotypic plasticity) that parasites use to maximize their transmission. It is now becoming increasingly clear that to understand and predict population level patterns of virulence and transmission, the processes that occur at the between-host level must be studied in light of the interactions that happen within hosts (between parasites and between parasites and hosts). In this thesis I combine concepts from evolutionary biology and ecology with tools from molecular and cellular biology and evolutionary genetics, which allow me to study rodent malaria parasites at both evolutionary and ecological timescales. The work I present in this thesis has the following four components: 1. Phylogenetics (chapter 2): I applied recently developed phylogenetic methods to a large DNA sequence dataset that I generated, to provide a better understanding of the phylogeny of rodent malaria parasites and investigate how selection has shaped their genomes. I show that all rodent malaria subspecies can be considered species, provide the first time line for the evolution of this group of parasites and demonstrate that most loci are under purifying selection. 2. Hybridization and reproductive isolation (chapter 3): I show that hybridization between two rodent malaria parasites (P. berghei and P. yoelii) can occur, but only occurs at high levels when one of two proteins (P230 or P48/45) is absent from the surface of female gametes, which indicates that these proteins are involved in gamete recognition. I find that P230, P48/45 and P47 (a possible interaction partner) are evolving under positive selection, a feature often observed in gamete recognition proteins of other taxa. Finally, I show that the fertilization success of P. berghei is reduced in the presence of P. yoelii, but not vice-versa, which indicates asymmetric reproductive interference. 3. Sex allocation (chapter 4): I carry the first test of sex allocation’s assumption that immunity impacts on the fertility of Plasmodium male gametocytes/gametes more than on the fertility of females. I show that while the fertility of both males and females is equally affected, males are affected during gametogenesis and females are mostly affected through gamete dysfunction (i.e. gametes can mate but zygotes fail to develop), which is in agreement with the assumptions of theory. In collaboration, I incorporate these effects into sex allocation theory and predict that malaria parasites can minimize the effects of factors that kill gametocytes/gametes by adjusting their sex ratios. On the other hand sex ratio adjustment cannot compensate for gamete dysfunction or zygote death. These results have applied implications for transmission-blocking vaccines. 4. Infection dynamics of mixed-species infections (chapter 5): I develop a series of experiments to test how a focal parasite species (P. yoelii) is affected by competition with heterospecifics (P. chabaudi) and how the interaction between the two species is mediated by immunity and resource availability. I show that P. chabaudi can boost P. yoelii above its single species level (i.e. facilitation) and that this is mediated by resource availability. On the other hand, P. yoelii’s performance can also be hindered in mice that were exposed to a P. chabaudi infection. My results also reveal that host mortality is exacerbated in mixed-species infections of naïve mice, which may be due to an inability of the host to achieve the right balance between the production and the destruction of red blood cells, when dealing with a mixed-species infection. The work I present here tackles fundamental questions concerning the transmission biology and the within-host interactions of malaria parasites The results presented demonstrate the importance of interactions between hosts and parasites and between different parasite species (at the molecular and the whole organism levels) for determining the outcome of transmission, virulence and within-host parasite performance.

The study of animal personality, i.e. consistent individual differences in animal behaviour, is a rapidly growing research field. The construct of personality has been studied in many different scientific disciplines including ethology, behavioural ecology, psychology, animal management and physiology. Studying personality using a comparative framework is important for establishing whether phylogeny and/or ecology are a driving force in personality development. The applied use of personality assessments to aid captive animal management could also have far reaching ramifications, as recent studies have demonstrated that personality has relationships with variables such as health, welfare and breeding success. Within the animal personality literature three main methods of assessing personality have been developed: i) coding behavioural data under natural conditions, ii) coding animals’ responses during novelty tests and iii) rating animals on sets of behaviourally defined traits. In the current study personality was investigated in three primate species, Sulawesi black crested macaques (Macaca nigra), barbary macaques (Macaca sylvanus) and common squirrel monkeys (Saimiri sciureus). The two macaque species are closely related, being from the same genus, but show some differences in their ecology and behaviour while S. sciureus are phylogentically distinct but exhibit some similarities to the two macaque species in certain aspects of their ecology and behaviour. The aims of the study were twofold: i) establish whether phylogeny or socioecology has an impact on the development of personality structure by comparing the study species with other primate species, and ii) evaluate the use of personality assessments as a tool for the management of the study species in captivity. Personality was assessed using the trait rating method. Questionnaires consisting of 38 personality traits, with accompanying definitions, were sent to all European institutions holding any of the study species. Keepers were required to rate animals on each trait using a 1 – 7 interval scale. Personality assessments were tested for inter-observer reliability. For each species a Principal Components Analysis (PCA) was carried out using only traits that exhibited good inter-observer reliability and scores for animals on each of the resulting components (personality dimensions) were calculated. Construct validity of the personality dimensions was assessed by evaluating the relationships between personality dimension scores and, i) behaviour under natural conditions, and ii) behaviour during a novel object test. In order to assess the management implications of personality assessments further analyses were carried out using the personality dimension data, i) a MANOVA was used to assess whether personality dimension scores were affected by Zoo, Age and Sex, ii) Generalised Linear Mixed Models (GLMMs) were used to assess which, if any, specific Zoo variables effect mean personality scores, iii) multiple regression and ANOVA analyses were carried out to establish whether personality dimension scores could predict breeding variables in M. nigra, iv) parent-offspring regressions were used to assess the heritability of personality dimensions in M. nigra, and v) correlation and General Linear Model (GLM) analyses were used to assess whether personality dimension scores effected behavioural measures of enrichment use in aM. nigra group. Twenty four traits in M. nigra (N= 64), 25 traits in M. sylvanus (N= 62) and 18 traits in S. sciureus (N= 69)were rated reliably by human observers. When reliable traits were entered into a PCA for each species, results revealed three personality dimensions for M. nigra, Sociability, Dominance, and Emotionality; four personality dimensions for M. sylvanus, Sociability, Dominance, Emotionality and Human-Animal Sociability (HA-Sociability); and three personality dimensions for S. sciureus, Sociability, Dominance, and Cautiousness. Construct validity of each species personality ratings, in terms of relationships with observable behaviour, was demonstrated for each species. Validity was affected by contextual variables such as Zoo, Age and Sex, which, as personality can vary with the variables (see below) was to be expected. MANOVA results showed that the variable ‘Zoo’ had significant effects on personality dimension scores in all three species. Further investigation using GLMMs revealed that i) in M. nigra mean Sociability scores were higher in groups with a lower mean age, ii) in S. sciureus mean Sociability scores were higher in groups where keepers had a high mean experience (months) working with the animals, and iii) again in S. sciureus mean Cautiousness scores were higher in groups with a small total group size. Multiple regression showed that personality dimension scores could not predict breeding success variables in either male or female M. nigra individuals. Of the three variables that could affect the breeding success of a male/female partnership, Male, Female and Zoo, only Male identity significantly affected breeding success but this could not be assessed against personality.Of the three M. nigra personality dimensions only one, Sociability, appears to have a heritable component. There were no significant correlations between personality dimension scores of individual M. nigra and measures of enrichment use across a range of enrichment devices. Repeated measures GLM revealed that while the individuals did spend significantly different amounts of time interacting with each of the enrichment devices this did not vary as a function of either repetition number or personality. When comparing the three study species with other primate species, the Sociability and Dominance dimensions were comparable with previous research on non-human primates (NHP), except that aggressive-type traits found in other studies were not present in the Dominance dimension in M. nigra and M. sylvanus. This may be attributed to data suggesting they have more tolerant social systems compared to other primate species. The Emotionality dimension was similar across the two macaque species and was comparable to analogous dimensions in other NHP species. The Cautiousness dimension in S. sciureus was found to be similar to dimensions such as fearfulness and bold/shy in other NHP species. The HA-Sociability dimension found in M. sylvanus could not be compared with other primate studies as, to date, there has been limited investigation of human-directed personality dimensions in captive primates. Quantitative analyses using partial Mantel tests were conducted to evaluate if either phylogenetic similarity or similarity in socioecological variables significantly correlated with similarities in personality structure for 11 primate species (including the three study species). The results of this analysis were inconclusive as neither phylogenetic similarity nor socioecological similarity had a significant correlation with personality similarity. However the effect of socioecology was approaching significance, indicating that, selection pressures related to socioecology may play an important role in shaping personality structure but further data collection on a wider range of species is needed to explore these relationships further. In terms of the management of the study species in the current study, it was demonstrated that the captive environment, particularly the social environment and human-animal relationships (HARs), has a significant impact on personality and so personality could prove to be a valuable management tool. Breeding success of M. nigra could not be predicted by personality and this could be an indicator that M. nigra actually adapt to life in captivity relatively well compared to some other species.