Using An Agent-Based Model To Study The Effect Of Reproductive Skew On Mongoose Populations

Reproductive skew is the name given to the unequal partitioning of breeding within social groups. Within these groups a mating hierarchy emerges wherein one dominant mating pair holds an unproportional majority of the group\u27s reproductive benefit, while other members mate infrequently, yet allocate energy and resources toward the offspring of the dominant group members. In this paper, we use an agent-based model, which mimics dwarf and banded mongoose populations, to investigate how reproductive skew aftects the speed natural selection, and thus how reproductive skew affects fitness. The results of the model show that due to the geometric structure of skewed breeding colonies, reproductive skew does increase the rate of natural selection. This result is consistent with the constructal law theory. Our results shed some light on skew theory and additionally have possible implications in conservation biology and artificial intelligence, through the genetic algorithm

Individual differences and variation in the reproductive strategies of cooperative breeders

Ecological differences are instrumental to the evolution of cooperative breeding, because they mean that the costs and benefits of forming a group and sharing reproduction differ between individuals and environments. Current evolutionary models do not fully explain the diversity of cooperative breeders' strategies, which suggests that these models neglect important ecological factors and are insufficiently complex. The goal of this PhD is to understand the factors that influence the evolution of cooperative-breeding strategies. My thesis incorporates some of the overlooked individual variation and uncertainty into models of skew, to get further insights into the reproductive games of cooperative breeders. I combine theoretical and empirical approaches, including a cross-species comparison and a dataset analysis. We first develop a model which reveals that the link between subordinate outside options and their effect on group productivity shapes skew and group formation. Using a meta-analysis I find that relatedness correlates positively with skew within species, suggesting that kin forego reproduction because the indirect benefits of helping are sufficient. We then develop a theoretical model to explore the effect of uncertainty which predicts that dominants should evolve to acquire information about the outside options of subordinates, but not their relatedness to those subordinates. Another key facet of variation is sex differences in life histories, which might select for different response rules for costly cooperative behaviours and reproductive strategies. While parental conflict and reproductive conflict both influence group productivity in theoretical models, my work shows that combining these two games does not change their predictions, which suggests that they can be studied separately. Using data from wild dwarf mongooses (Helogale parvula), I uncovered an interaction between sex and period in contributions to costly sentinel activity, with males contributing more than females in the second fortnight after individuals acquire dominance. Empirical studies testing the predictions of this thesis are needed to determine whether their hold true. Future studies should investigate how variation and uncertainty about other factors influence evolutionary games, to define what influences animals’ strategies.NER

Do maternal effects influence phenotypic traits in a cooperatively breeding mammal?

Animals within populations show considerable variation in physiological and behavioural traits. These phenotypic differences can be profoundly influenced by the ecological and social conditions experienced in early life. Usually, adverse early life conditions, such as low food availability, will constrain offspring development. However, recent studies suggest that in some contexts suboptimal developmental conditions may be associated with fitness benefits. In this thesis I consider the ultimate and proximate mechanisms underlying individual variation in a cooperatively breeding mammal. I use hormone samples and the long-term dataset from the banded mongoose research project to investigate the social factors that influence early life stress and how patterns of reproductive investment change with maternal age. In chapter one I review current theories on the function of glucocorticoid (GC) hormones and give an overview of maternal stress and its effect on offspring development and physiology. In addition, I discuss the influence of maternal effects on cooperatively breeding systems. In chapter two, I introduce the study population and provide a general outline of the methods used in data collection and analysis. In chapter three, I test how maternal effects, specifically maternal rank, influence GC concentrations in banded mongoose pups and whether elevated early life GC is associated with mortality risk. I also consider whether the amount of cooperative care received by offspring in early life affects their GC concentrations. In chapter four, I use a larger dataset to consider how maternal effects influence adult life- history traits. I examine the influence that maternal age has on offspring survival, longevity and reproductive success and consider whether any effects might be sex- specific. I also ask whether age-related optimal maternal investment strategies can influence offspring sex ratios. In chapter five, I synthesis my findings and attempt to draw on the wider implications and make suggestions for future study

Odour signals contain multi-modal information in the banded mongoose (Mungos mungo).

Communication can be crucial to the profitability of reproduction by allowing individuals to attract and select an appropriate mate. Across mammals, successful reproduction can depend on the ability of individuals to gain information such as relatedness, health parameters and breeding status from potential mates. Although visual and auditory signals are utilised, scent is a crucial and ancient form of communication yet, with the exception of certain model systems, we understand little of how it functions in wild mammals. This thesis will focus on the mechanistic role of odour signals: what information they contain and how they may facilitate reproductive decision-making in the banded mongoose (Mungos mungo). I use a wild but habituated population to conduct experimental odour presentations showing these mammals are capable of discriminating scents based on sex, familiarity, relatedness and female reproductive state. The ability of odours to encode such multi-modal information suggests they may facilitate key behavioural processes such as kin recognition, mate-choice and competitive interactions. However, the discrimination of pregnancy specifically implies scent cues function within reproductive decision-making, attracting males to receptive mates. The gastro-intestinal parasite community of this banded mongoose population was also screened, allowing the ability of odour cues to advertise parasitic infection to be tested. Observations show highly parasitised individuals scent-mark less frequently, suggesting marking behaviour indicates quality in terms of parasite burdens. Furthermore, experimental odour presentations show that banded mongooses exhibit behavioural aversions toward odours of heavily infected individuals. Scent cues, in the banded mongoose system, thus appear to encode a multitude of information relevant to reproduction

Modelling sociality in carnivores

Ph. D. ThesisMany theories have been put forward as potential explanations for social behaviour in carnivores, yet there is little consensus as to the factors that drive the formation of groups and social behaviours. Traditionally two selection pressures have been postulated to explain why animals are social; the exploitation of resources and avoidance of predation. Much of the work investigating sociality has focussed on single factors to explain group formation. However, many of these factors such as life history, diet, predation risk, and habitat use are confounded, operating at different temporal and spatial scales but interacting nonetheless. Thus it is important to investigate sociality in the context of multiple factors to understand how their complexity may influence social behaviours. This work investigates factors affecting sociality across narrowing scales to test hypotheses of the factors driving the formation of social groups and the resulting social behaviours. Topic modelling of descriptive data was used to understand behavioural similarities between species. Formalising the hypotheses of sociality as models and testing them with quantitative data demonstrated the relative importance of life history and environmental factors on the formation of social groups in different species. At a population level this interaction between the group and their environment is demonstrated to influence the demography of the group in a socially plastic species. Within populations individual based models show support for the hypothesis that the formation of social groupings is driven by energetic demands. Understanding the conditions that favour sociality within a species or population beyond predation and resource exploitation could prove useful for informing the management and conservation of carnivores, many of which are under threat. This thesis has evidenced, through multiple modelling approaches, the importance of integrating life history data and environmental information when considering the conditions under which social behaviours are exhibited

Cooperation and competition in wild male Barbary macaques (Macaca sylvanus) in Morocco

Männliche Säugetiere konkurrieren um eine nicht-teilbare Ressource (empfängnisbereite Weibchen) und sind üblicherweise das abwandernde Geschlecht, weshalb Kooperation zwischen Männchen der Intuition zu widersprechen scheint. Wenn die Kooperation jedoch für beide Partner vorteilhaft ist, indem sich z.B. ihr Paarungs-/Fortpflanzungserfolg erhöht, kann Kooperation eine plausible Strategie sein. Koalitionen können opportunistisch sein, also kurzfristig einen direkten Nutzen bieten, oder für einen zukünftigen Fortpflanzungserfolg und Aufstieg in der Rangordnung sorgen. Welche Art von Koalition auftritt, hängt von dem Konkurrenzpotential innerhalb einer Gruppe ab, das von der Fähigkeit des alpha-Männchen, rezeptive Weibchen zu monopolisieren, bestimmt wird. Es wird davon ausgegangen, dass Männchen den Rang bzw. die Stärke von potentiellen Koalitionspartnern und Kontrahenten abwägen müssen, um einen Partner zu rekrutieren, so dass die gemeinsame intrinsische Kampfkraft ausreicht um den Kontrahenten zu besiegen. Alternativ können Männchen vorherige Erfahrungen mit Gruppenmitgliedern nutzen, um zu entscheiden wen sie rekrutieren ("attitudinal partner choice") und verlässliche Partner wählen. Unter solchen Bedingungen kann die Wahl des Koalitionspartners durch Sozialbeziehungen beeinflusst werden. Diese Doktorarbeit sollte Aufschluss geben über die Kooperation zwischen Männchen, indem die Paarungskonkurrenz und Sozialbeziehungen von Männchen und der Einfluss von Koalitionen in einer gruppenlebenden, wilden Primatenart, dem Berberaffen (Macaca sylvanus), untersucht wurden. Dazu habe ich einen Bottom-Up-Ansatz genutzt, indem ich die vollständige Folge von Ereignissen analysierte, die zu Kooperation zwischen Männchen führte. Ich habe bestimmt, inwiefern Männchen den reproduktiven Zustand von Weibchen feststellen können, um das Potential zur Paarungskonkurrenz innerhalb von Gruppen empirisch abschätzen zu können. Ich habe das "Priority-of-Access"-Modell als Grundlage für eine Erforschung der männlichen Paarungskonkurrenz genutzt und habe die Faktoren untersucht, die zu Abweichungen von den Vorhersagen des Modells führen, vornehmlich das Verhalten der Weibchen und die männliche Koalitionsbildung. Die artspezifische Messung der Konkurrenz zwischen Männchen erlaubte eine kritische Evaluation eines mathematischen Modells, das konzipiert wurde, um verschiedene Typen von Koalitionsbildung innerhalb von Gruppen vorherzusagen (Pandit/van Schaik-Koalitionsmodell). Im Besonderen habe ich untersucht, wie die Vorhersagen des Modells zu empirischen Daten zweier Arten mit variablem Konkurrenzpotential (Berberaffen und Assam-Makaken, M. assamensis) passen. Die Sozialbeziehungen von Männchen wurden analysiert, um festzustellen, ob Berberaffen selbst in Zeiten intensiver Konkurrenz (während der Paarungszeit) langfristige Beziehungen formen. Schlussendlich wurde die Stärke männlicher Sozialbeziehungen untersucht um zu ermitteln, ob sie einen Anpassungswert durch die Kooperation in der Koalitionsbildung bieten, oder ob Koalitionspartner allein aufgrund ihres Dominanzstatus ausgewählt wurden. Es wurden Daten zweier Gruppen freilebender Berberaffen im Mittleren Atlasgebirge Marokkos von September 2009 bis August 2011 gesammelt. Ich habe über 2000 Stunden Verhaltensdaten aller Männchen in beiden Gruppen nach der Focus-Tier-Methode sowie ad libitum gesammelt, und 549 Koalitionen verschiedener Größe und unterschiedlichen Erfolges beobachtet. Zusätzlich wurden 155 weibliche Kotproben analysiert, um das Datum der Empfängnis mittels Enzymimmunassays von Gestagenmetaboliten festzustellen. Außerdem wurden weibliche Sexualschwellungen visuell eingestuft, um die Synchronität der Empfängnisse zu ermitteln. Die Analyse der weiblichen Hormonkonzentrationen zeigt, dass die Ovulation am wahrscheinlichsten im Zeitraum maximaler Sexualschwellung standfand. Allerdings konzentrierte sich das männliche Paarungsverhalten stärker auf die fertile Phase, was impliziert, das Männchen mehr als nur die Schwellungen an sich als Information nutzen können. Die Paarungshäufigkeit der Männchen stieg im Einklang mit dem sexualen Sozialverhalten der Weibchen. Bemerkenswerterweise zeigen meine Ergebnisse, dass Männchen gleichermaßen in Paarungen während der fertilen und nicht-fertilen (d.h. nach der Empfängnis) Phasen der Sexualschwellungen investieren. Obwohl diese zusätzlichen Sexualschwellungen das Monopolisierungspotential hochrangiger Männchen verringern, waren Paarungen zu Gunsten hochrangiger Männchen verschoben. Hochrangige Männchen haben aber keinen so großen Anteil der Paarungen erzielt, wie vom "Priority-of-Access"-Modell vorhergesagt wird. Weibchen haben regelmäßig Paarungen initiiert, in erster Linie mit mittelrangigen Männchen, was deren Paarungserfolg erhöhte, während Koaltionsbildung von Männchen deren Paarungserfolg unabhängig davon erhöhte. Regelmäßige Assoziationen mit Weibchen waren kostspielig für Männchen, da sie Ziele überbrückender Koalitionen ("bridging coalitions") wurden, was ihre zukünftigen Paarungsmöglichkeiten einschränkte. Hochrangige Männchen haben ihren Paarungserfolg nicht direkt mittels überbrückender Koalitionen ("bridging coalitions") erhöht, minderten aber den Einfluss des weiblichen Verhaltens. Außerdem bildeten Berberaffenmännchen langfristige Sozialbeziehungen die durch die höchst kompetitiven Paarungzeiten hindurch bestehen blieben. Männchen mit einer starken sozialen Bindung wurden mit höherer Wahrscheinlichkeit als Koalitionspartner rekrutiert, was nahe legt, dass für Männchen mehr als nur der Rang der verfügbaren Partner ausschlaggebend ist. Eine Prüfung des Pandit/van Schaik-Koalitionsmodells zeigte, dass unter hohem Konkurrenzpotential opportunistische Koalitionen genutzt werden sollten, um Zugang zu Weibchen zu gewinnen, die von hochrangigen Männchen monopolisiert sind. Indessen stimmten die empirischen Daten nicht mit den Vorhersagen unter mittlerem bis niedrigem Konkurrenzpotentials überein, bei dem männliche Affiliationen Rang-verändernde Koalitionen erleichtern könnten. Für diese werden vertrauenswürdige Partner benötigt, um die höherrangige Position zu verteidigen, sobald sie gewonnen wurde. Demnach können enge soziale Bindungen zwischen Männchen sowohl kurz- als auch langfristige Vorteile liefern, indem die Wahrscheinlichkeit, dass der Partner während einer Koalition abtrünnig wird, verringert wird. Zudem steht ein langfristiger Partner zur Verfügung, der erfolgreiche Rangveränderungen erleichtert wodurch enge soziale Bindungen letzlich sowohl den Status als auch den Paarungs-/Fortpflanzungserfolg erhöhen. Zusammenfassend erweitert meine Doktorarbeit die derzeitige Literatur über den Zusammenhang zwischen männlichen Fortpflanzungsstrategien, Sozialbeziehungen und Kooperation innerhalb von gruppenlebenden Säugetieren mit abwandernden Männchen. Durch die Untersuchung der vollständigen Beweiskette vom zwischenmännlichem Konkurrenzkampf hin zu Paarungserfolg und Kooperation durch das Schließen enger zwischenmännlicher Sozialbindungen, ergibt diese Studie ein umfassendes Bild mehrerer unabhängiger Forschungsansätze und könnte eine Vorlage für zukünftige Forschungsarbeiten bilden. Koalitionsbildung kann mutualistische Vorteile für beide Partner liefern, was nahelegt, dass Kooperation durch vorherige affiliative Interaktionen mit Gruppenmitgliedern durch "attitudinal partner choice" bestimmt sein könnte.Mammalian males compete for a non-sharable resource (receptive females) and are typically the dispersing sex, thus cooperation between males may appear counterintuitive. However, if both partners gain mutual benefits from cooperating, such as an increase in mating/reproductive success, then cooperation can become a feasible strategy. Coalitions can be opportunistic, in the short-term providing direct benefits or can function to increase rank positions and provide future reproductive payoffs. These coalition types are predicted to occur at different levels of within group contest potential predicted by the monopolization potential of the alpha male over access to receptive females. It has been suggested males must weigh-up the rank/strength of the potential allies and the target to recruit a partner who will provide enough combined intrinsic fighting ability to defeat the target. Alternatively, males may base partner recruitment decisions on past experiences with group members (attitudinal partner choice) and regularly recruit reliable partners. Coalitionary partner choice may be mediated via social bonds under such circumstances.  The aim of this thesis was to shed light on male cooperation by examining male mating competition and social relationships and how these are influenced by coalitionary activity in a group living, wild, primate with male dispersal, the Barbary macaque (Macaca sylvanus). To this end I used a bottom-up approach, by examining the complete chain of events which led to male-male cooperation. I determined what males can ascertain about female reproductive state to gain an empirical estimate of mating contest potential within the groups. I utilised the Priority of Access model as a platform to investigate male mating competition and I examined the factors which led to deviation from the models predictions, namely female behaviour and male coalition formation. Species specific measures of male contest allowed for a critical evaluation of a mathematical model designed to predict different types of within group coalition formation (Pandit/van Schaik coalition model). Specifically, I examined how the model’s predictions fitted to empirical data across two species with variable contest potentials (Barbary and Assamese macaques, M. assamensis). Male social relationships were analysed to determine if Barbary macaque males formed long-term social relationships, even during intense periods of competition (mating seasons). Finally, male social bond strength was examined to identify if they provided an adaptive benefit in terms of cooperation through coalition formation or if coalition partners were selected by hierarchal status alone.  Data were collected on two groups of wild Barbary macaques in the Middle Atlas Mountains, Morocco (Sept. 2009-Aug. 2011). I collected over 2,000 hours of behavioural focal observations on all male subjects in the two groups as well as ad libitum data and 549 coalition bouts were observed of various size and success. Additionally, 155 female faecal samples were analysed to assess dates of conception using enzyme immune assays of progestogen metabolites, as well as visual monitoring of female sexual swelling size to determine receptive synchrony.  Analysis of female hormone concentrations revealed ovulation was most likely to occur during the maximum swelling period. However, male mating behaviour was further concentrated around the fertile phase implying that males infer information from more than swelling size alone. Male mating frequency increased in line with female socio-sexual behaviour. Most strikingly my results showed that males invested equally in mating during fertile and non-fertile, i.e. post-conception, maximum swelling phases. Despite these additional swelling periods reducing monopolisation potential of high ranked males mating was still skewed up the hierarchy but high ranked males did not gain as large a share as expected by the Priority of Access model. Females frequently initiated sexual encounters, predominantly with mid-ranked males, increasing their mating success while male coalitionary activity independently increased mating success. Frequent associations with females were costly to males as they were the targets of bridging coalitions, decreasing future mating opportunities for the targets. High-ranking males did not increase their mating success directly through bridging coalitions but acted to dilute the effects of female mating behaviour. Furthermore, Barbary macaque males formed long-term social bonds enduring through highly competitive mating seasons. Males who shared strong social bonds were more likely to be recruited as coalition partners suggesting that males use more than merely rank position of available partners when recruiting. Examination of the Pandit/van Schaik coalition model showed that at high contest potential opportunistic coalitions should be utilized to gain access to females monopolised by high ranked males. Whereas the empirical data did not match the predictions at mid-low contest potential where male affiliation may play a role in facilitating rank-changing coalitions which require reliable partners to defend higher rank positions once obtained. Thus, strong social bonds can provide both short- and long-term benefits by reducing the likelihood of partner defection during coalitions and providing a long-term partner to facilitate successful rank-changes and ultimately increase both status and mating/reproductive success. In sum, my thesis adds to the current literature on the links between male reproductive strategies, social bonding and cooperation in group living mammalian societies, with male dispersal. Through investigation of the complete chain of evidence from male contest competition to mating success and cooperation via male social bonding, this study united several previously separate pieces of research into one comprehensive picture and may provide a template for future research. Coalitionary activity can provide mutual benefits for both partners suggesting that cooperation may be based on previous affiliative interactions with group members brought about by attitudinal partner choice

Models of conflict and voluntary cooperation between individuals in non-egalitarian social groups

This thesis broadly investigates the evolution of voluntary cooperative behaviour among individuals in conflict in non-egalitarian social groups. This work is partitioned into three sections. In the first section, we explore the emergence of non-egalitarian social groups to better understand the evolutionary incentives for voluntary participation in groups with unequal distributions of resources. In the second section, we study several scenarios in which genetically related individuals with unequal control over resources cooperate despite being in conflict. The evolution of parent-offspring conflict over provisioning, offspring signals, and alloparental care are each addressed in this section. In the last section, we investigate cooperative behaviours between unrelated individuals in conflict by modelling the evolution of coalitionary behaviour

Life on the edge: exploring the effects of urbanisation on the foraging ecology and ecotoxicology of caracals

The continuing loss of natural habitat to a broad range of human activities is one of the main drivers of biodiversity decline worldwide and a defining feature of the Anthropocene. However, some opportunistic, generalist species may benefit from transformed landscapes through, for example, the absence of apex predators or access to human-subsidised food resources. These benefits may thus offset the higher mortality and health risks typically associated with human-dominated landscapes. To understand the cost-benefit trade-offs of life on the urban edge, I investigated the foraging ecology and ecotoxicology of a highly adaptable medium-sized carnivore, the caracal (Caracal caracal), utilising both natural and transformed landscapes around the rapidly growing city of Cape Town, South Africa. Through a combination of scat analysis (n = 654 scats) and prey remains located at 677 GPS clusters, I quantified dietary resource use of 26 collared individuals, as well as opportunistically sampled caracals. Using a range of gut transit times, I estimated whether scat at cluster sites was from the same or an earlier feeding event, thereby increasing the overall detection of individual-specific feeding events by > 50%. While most feeding events occurred within 200 m of the urban edge of Cape Town, I found that caracals have flexible diets that largely comprise medium- to small-sized wild prey (60%), followed by human-associated species (27%), and introduced or domestic species (13%). Using a subset of the feeding and resting events (n = 326 prey remains, n = 384 scat, n = 177 resting sites) that were associated with known individuals (n = 17), I then investigated caracal resource selection using both anthropogenic and environmental factors. Additionally, I examined the behaviour of caracal at feeding clusters to determine if they respond to spatial and temporal risks associated with anthropogenic factors. I found divergent resource selection patterns based on the level of exposure to urbanisation: caracals living in the urban-dominated region of the Peninsula (n = 14; 548 feeding events) select for the urban edge, while caracals in the wildland-dominated region (n = 3; 162 feeding events) strongly avoid it. I argue that in the more urbanised region, caracals forage on or close to the urban edge because this is where the remaining low-lying wildland habitat is most productive and attractive. Consequently, caracals in heavily transformed areas, which might otherwise tend to avoid human disturbance, have habituated to human presence but reduce their risk of detection by remaining cryptic, prolonging handling time, and maintaining high feeding site fidelity where cover is available. To quantify the consequences of peri-urban foraging, I use an ecotoxicological approach to assess environmental contamination and its potential effects on caracals. It is widely reported that persistent organic pollutants (POPs), including organochlorines (OCs) such as PCBs and DDT and its metabolites, are extremely toxic, causing adverse effects on wildlife and human health. I tested blood and adipose tissues of caracals, with different diets utilising a range of natural and transformed landscapes, for exposure to commonly detected OCs. Despite restrictions on their use, I found extensive OC burdens, with 100% of adipose samples exposed to both DDT and PCBs, and 100% and 83% of blood samples exposed to DDT and PCBs respectively. Caracals using areas with a higher density of people and electrical transformers, and those using areas close to informal settlements, had higher exposure to OCs. Additionally, the use of vineyards and wetlands and a diet with a greater proportion of higher trophic level or exotic prey correlated with a higher risk of exposure to OC pollutants. Full blood analyses revealed that exposure levels to OCs were also associated with higher counts of infection-fighting cells, suggesting these compounds may affect the immune response of individuals. With time, these detrimental effects may have population-level repercussions through impacts on reproductive success and fitness. Together these findings reveal that while caracals and other medium-sized adaptable carnivores may persist within or adjacent to human transformed habitats, they still prefer natural habitat and pay a significant cost for foraging on prey species that have been contaminated by pollutants associated with urban and rural land uses. Urban edges may thus be an ecotoxicological trap, threatening the health and long-term persistence of caracals and other wildlife in this and other biodiversity hotspots. Reducing environmental contamination and limiting habitat loss to urban sprawl would benefit wildlife living on the transformed edges but requires significant improvements to both the legislation governing pollutants and the spatial planning of cities

The tuber-feeding weevil Listronotus frontalis as a candidate biological control agent for the invasive semi-aquatic plant Sagittaria platyphylla within South Africa

Sagittaria platyphylla (Engelm.) J.G.Sm. (Alismataceae) is an invasive, aquatic macrophyte originating in the southern United States of America. In South Africa, the plant was first detected in Krantzkloof Nature Reserve, KwaZulu-Natal Province in 2008, and due to its known impact in other countries, it was listed as a Category 1a invader species under the National Environmental Management: Biodiversity Act 2004 (NEM:BA). This invasive plant has proved difficult to manage due to its varied growth forms and reproductive strategies, such as prolific seed and below ground tuber production. Due to the limitations of conventional control mechanisms, biological control is currently being considered as a potential control option. The tuber feeding weevil Listronotus frontalis LeConte (Coleoptera: Curculionidae) has been identified as a candidate biological control agent for this invasive species. The aims of this study were twofold; to firstly determine the importance of tubers to S. platyphylla populations growing in South Africa; and secondly, to determine the biology and suitability of L. frontalis, a tuber feeder, as a candidate biological control agent. Surveys of S. platyphylla populations in South Africa showed that tubers were found in all sampled sites, except for Krantzkloof Nature reserve in KwaZulu-Natal Province. The highest number of tubers was 97.75 ± 10.62 (SE) m-2 recorded at Jonkershoek in the Western Cape Province. Monthly sampling from two sites in the Eastern Cape Province, the Makana Botanical Gardens and Maden Dam showed that neither season nor water depth affected tuber production. However, the mean number of tubers as well as mass of tubers sampled, were consistently higher (F(1,179) = 20.9542, P < 0.0001) and heavier (F(1, 857) = 585.7293, P < 0.0001) at the Botanical Gardens than at Maden Dam, respectively. The study showed that tubers are an important life stage of S. platyphylla populations and may vary in size and abundance between and within sites. The tuber feeding weevil was shown to develop from egg to ovipositing adult within just over 40 days. Females were recorded to lay up to 48 eggs within a period of one week. Impact studies showed that adult feeding led to a reduction in all but one of the 11 measured plant growth and developmental measurements, including a reduction in the mean mass of the above-ground plant material (F(2,2743) = 12.05, P = 0.002) as well as a reduction in size and abundance of tubers (F(2,58.47) = 9.756, P = 0.0006) and stolons(F(14.943) = 8.7577, P = 0.003). These results are encouraging and suggest that if the insect is released in South Africa, it may prove to be a valuable biocontrol agent. It is concluded that, until suitable biological control options become available in South Africa, the chemical and mechanical control measures currently implemented should continue, however, controlling tubers should be considered during the planning and implementation of these strategies.Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 202

Application of genetic techniques to conservation of the Critically Endangered Grenada Dove Leptotila wellsi

The Grenada Dove Leptotila wellsi is a Critically Endangered species endemic to the island of Grenada. It exists in two geographically isolated populations across the island. As an endemic on a small island with a limited and decreasing population, this species is at risk from genetic deterioration. Particular risks include inbreeding depression and accelerated loss of genetic diversity resulting from ongoing habitat fragmentation and population isolation. The work reported in this thesis aimed to provide the first genetic data for the Grenada Dove, assess its genetic status and determine what conservation management recommendations can be made to help ensure its long-term survival. A systematic literature review revealed geographical bias in how genetic approaches have been applied to the conservation of island bird species, under-representation of threatened species and highlighted a gap between genetic research and active conservation management. A protocol for obtaining usable genetic material from moulted plumulaceous feather samples was developed and showed that samples collected non-invasively in the field, that were kept in non-optimal conditions for deoxyribonucleic acid (DNA) extraction, can be used effectively to sequence informative regions of mitochondrial DNA (mtDNA) for genetic analysis. The evolutionary and life history of the Grenada Dove were investigated by estimating its phylogenetic placement and using phylogenetic comparative methods for estimating unknown life history traits. The Grey-Chested Dove Leptotila cassinii was identified as the species with which the Grenada Dove shares the most recent common ancestor, with an estimated divergence of approximately 2.53 million years ago. Life history trait values were predicted for the Grenada Dove and suggest this species will be slow to recover after a major population decline. The mitochondrial genetic diversity of Grenada Dove populations was assessed for the two areas of occupancy. Two haplotypes were identified with one haplotype unique to the population in the West. Selective neutrality tests Fu’s Fs=0.78 and Tajima’s D=0.83 were positive and not significant, with an FST value = 0.71 suggesting a marked genetic divergence between the two populations. This study showed low mitochondrial genetic diversity, a non-expanding population and iii | iii clear evidence for genetically isolated populations. Population viability analysis (PVA) was used to evaluate extinction risk and the potential for conservation management for the two populations of the Grenada Dove. This PVA identified that loss of forest habitat to commercial development is likely to have the biggest impact on extant populations and that conservation management to increase productivity is likely be the most effective conservation strategy. This thesis contributes novel information regarding evolutionary history, life history, population genetics and future population trajectories to inform long-term conservation actions for the Critically Endangered Grenada Dove