M.Sc. / Please refer to full text to view abstract

Behaviour and space utilisation of rock-dwelling cichlids were observed at Thumbi East Island, Lake Malawi. 1. Males of five species of the mbuna complex held long-term territories. Pseudotropheus elongatus "aggressive" vigorously defended a feeding area and sometimes a spawning site interspecifically, but did not feed in the peripheral part of their territory. Spawning sites of Pseudotropheus zebra, Pseudotropheus tropheops "orange chest", Labeotropheus fuelleborni, and Petrotilapia nigra were interspecifically-defended, while larger mating territories were defended against conspecific neighbours. Feeding areas were shared with many fish and often extended beyond the defended area. There was considerable variation in behaviour and space use within and between species and between times of day. 2. Non-territorial P. zebra used larger ranges than territorial conspecifics, and fed more on plankton, but individuals had preferred benthic feeding areas, often in conspecific territories. These 'floaters' were often aggressive. Both size and relative brightness independently predicted the outcome of aggressive interactions between floaters, and a site-specific dominance hierarchy was suggested, with some individuals appearing to be semi-territorial. 3. Males and females of 21 and 13 species respectively were found to establish temporary breeding territories. Overall breeding seasonality was bimodal, but reproductive timing and territory characteristics differed among species. Temporary territories had a considerable impact on the behaviour and habitat use of all resident mbuna species, even causing abandonment of territories. 4. Non-breeding Protomelas taeniolatus had limited home ranges, and showed little aggression. During the highly-synchronised reproductive season, males defended spawning sites and females fry-guarding territories. Most chases were directed towards the commonest fish, but predators were chased further and faster. Female behaviour changed over the guarding period. Females generally continued territorial defence after the brood had disappeared. Most broods contained fry of different sizes and species. Significant benefits were found for guarding females with clustered territories, but females did not appear to choose sites adjacent to conspecific parental females. 5. Territoriality in fish is taxonomically widespread and may serve several functions according to species, sex and developmental stage. It also varies according to genotype- and phenotype-limited strategies and short term costs and benefits. Territories may be simultaneously multifunctional.

A lek-breeding cichlid fish Pseudocrenilabrus philander was studied experimentally. Females in choice-chamber experiments showed no active choice for male size and colour, or for other male attributes, but preferred males which courted most actively. In a laboratory lek, the significant determinants of the strongly skewed mating success in males were territory size, side-shake and female chasing frequency. Together these three variables explained 79% of the variation in male mating success, with territory size alone accounting for 75% of the variation and the other two variables each accounting for 2% of the remaining variation. As there was no difference in territory quality in the laboratory lek, territory size became the principal measure of the effect of male-male competition since it was directly related to dominance. Both side-shake and female chasing could be identified as the basic factors influencing female choice, as they had an immediate effect on the display-response mating system of females. Thus, the relative importance of these three variables indicated that sexual selection in this particular lek mating species operated chiefly through the agency of intrasexual competition for dominance. However, both female behaviour and their requirement for a prolonged pre-spawning courtship had the effect of promoting male rivalry and favouring mating with dominant males. Although the intense male competition excluded subordinate males from practising normal courtship behaviour, competitively inferior males might "make the best of a bad situation" by facultatively adopting an alternative sneaking tactic to gain access to females. Spawning intrusions by females to steal freshly-laid eggs also occurred frequently. However, territorial males appeared to be relatively more tolerant of female intruders than male sneakers. Interference during spawning could lead to a longer pre-spawning courtship and even multiple-mating by females. The results of the present study and the behavioural evidence shown by males and females did not support the ʺrunaway selection modelʺ of the mating pattern in terms of sexual selection in leks, but conformed to the rival ʺwar propaganda modelʺ

La construction de cartes de génomes consiste à baliser les chromosomes par des repères : les marqueurs. Plus une carte est dense en marqueurs régulièrement espacés, plus elle est informative et donc plus les applications ultérieures sont nombreuses. Parmi les différentes stratégies de cartographie, celle exploitant les hybrides d'irradiation dite carte RH, présente de nombreux avantages. Ainsi, des marqueurs polymorphes tels que les microsatellites, utiles pour les analyses de liaisons génétiques et des marqueurs de gènes, polymorphes ou non polymorphes permettant d'établir des cartes comparées avec d'autres génomes et définir des zones de conservation ou de rupture de synténie, peuvent être localisés sur une carte RH. Ces cartes comparées sont utiles non seulement pour l'identification de gènes d'intérêts mais également pour l'étude de l'évolution des génomes. Parmi les nombreux vertébrés d’intérêt, nous nous sommes particulièrement attachés à la construction de cartes RH de poissons et de cichlidés en particulier. Ceux-ci constituent en effet un modèle génétique très intéressant du point de vue économique et évolutif. La réalisation de cartes des génomes de plusieurs poissons devrait aider à l'identification de gènes impliqués dans des traits phénotypiques ou pathologiques voire même des marqueurs liés aux stress et à la reproduction. Mon travail de thèse a consisté à construire une carte du génome du bar, un panel RH de tilapia et la carte RH attenante qui a été utilisée dans la phase finale de l’assemblage des données de séquence du génome de Tilapia. Par ailleurs nous avons construit un panel RH d’esturgeon et un autre d’huitre. La cartographie du génome de tilapia, réalisée dans le cadre d’un consortium international, nous a donné un accès privilégié aux données de séquences des génomes de cinq cichlidés (O. niloticus, P. nyererei, H. burtoni, N. brichardi et M. zebra) et nous a permis de participer à l’annotation de ces séquences génomiques en nous intéressant plus particulièrement à l’identification des répertoires des gènes codant pour les récepteurs olfactifs (OR) et les récepteurs connus sous le vocable de TAAR pour ‘ Trace Amine-Associated Receptors’. C’est ainsi que nous avons identifié et caractérisé 158, 88, 90, 69, 102 gènes OR et 45, 19, 23, 12, 20 gènes TAAR dans les génomes de ces cinq poissons (O. niloticus, P. nyererei, H. burtoni, N. brichardi et M. zebra) / The construction of genome maps consists in placing tags, called markers, on the chromosomes. The denser in evenly spaced markers is a map, the more it is informative, leading to the development of more future applications. Among the different mapping strategies, those using radiation hybrids (RH) have numerous advantages. Indeed, polymorphic markers such as microsatellites, useful for linkage analyses, as well as gene markers, polymorphic or not and allowing comparative mapping with other genomes and definition of synteny breaks and conservation, can be localized on a RH map. Not only these maps are useful to identify genes of interest but they are also essential tools to study genome evolution. Among numerous vertebrates of interest, we constructed RH maps of fishes and cichlids in particular. Indeed these fishes constitute interesting genetic models from economical and evolution points of view. Having genome maps of several of these fishes would help to identify genes implicated in phenotypical or pathological traits, or even markers linked to stress and reproduction. My thesis work consisted in the construction of a genome map of the sea bass, a tilapia RH panel and its RH map, a sturgeon RH panel as well as an oyster RH panel. The tilapia map was used for the assembly of the sequencing data of the tilapia genome. Thanks to this last work realized with an international consortium we had a privileged access to the sequencing data of five cichlid genomes (O. niloticus, P. nyererei, H. burtoni, N. brichardi and M. zebra). We then participated to the annotation of these genomic sequences. In particular we have identified and characterized the olfactory receptor gene (OR) repertoires and of the trace amine-associated receptor (TAAR) gene repertoires of these five cichlids. Which are then made of 158, 88, 90, 69, 102 OR genes and 45, 19, 23, 12, 20 TAAR genes respectively.

" In this study, I investigated the ritualized fights of male Nannacara anomala to show that each distinct phase (lateral display, tail beating, and mouth wrestling) of the fight is used to assess a different aspect of resource holding potential (aggressiveness, body size and swimming performance). When animals go into an agonistic encounter, they often have little or no previous knowledge of their opponent's fighting ability (or resource holding potential). Assessment is the process by which strangers gain information about each other through repetition of informative behaviors. Generally fights are ritualized so that specific behaviors are associated with distinct phases within the fight. Aggressiveness of fish was established by measuring response time to an aggressive conspecific. Weight was used as a measure of body size. Swimming performance (stamina and maximum swimming speed) was determined by swimming each fish in a variable speed flow tank. If all fights are taken into consideration, weight is the only factor for which winners were significantly different from losers (p = 0.009). However, if the fights are classified by the phase in which they ended, fights ending in tail beating have larger winners (p = 0.003) and fights ending in mouth wrestling have faster winners (p = 0.008). Opponents are using early stages of fights to assess body size and escalated stages to assess performance characteristics."

Vision plays a key role in life of many vertebrates, and the performance of visual system is often adapted to specific environments inhabited by individual species. Fish colonized a wide range of habitats and adjusted their visual abilities to maximize their success rates in hunting, reproduction and predator avoidance. This thesis is focused on molecular mechanism of visual system, namely on genes for photoreceptor proteins, opsins, of two major groups of teleost fishes: African riverine cichlids (family Cichlidae, order Cichliformes, part of larger taxa Percomorpha), and European freshwater cyprinids (family Cyprinidae, order Cypriniformes, part of larger taxa Ostariophysi). Two types of photoreceptor cells are present on retina: the cones and the rods. Actinopterygian fishes in general have four cone opsin types (SWS1, SWS2, RH2 and LWS) used for colour (photopic) vision, and one rod opsin type (rhodopsins) for vision in deteriorated light conditions (scotopic vision). In the present thesis, I focus on 1) DNA sequence and amino acid substitutions of the opsin genes, and on 2) gene expression levels of opsins sensitive to various wavelengths of light spectrum. The results of my work show that both cichlids (family Cichlidae) and cyprinids (family Cyprinidae) have a complete set of opsin genes in...

Work has the aim to describe charakteristics of scales selected species fish from the Central America and evaluace relationship with view on the group and compare scalimetric evolutional tree with molecular. Relationship between Heroini and Cichlasomatini is really close and Heroini constitute the second largest tribe of neotropical cichlids. These fish are very varied. Heroini is considered as monofyletic group. Development of the tribe in two branches. Theoretic part of this work is focused on phylogenetic knowledge from the other authors and group description. In the part with own issues there are characteristics of scales, microphotographs.

M.Sc. / The upper catchment of the Olifants River, from its origin near Bethal, to its confluence with the Wilge River, north of Witbank, as well as it tributaries, are being subjected to increasing afforestation, mining, power generation, irrigation, domestic and industrial activities. These activities have a profound effect on the water quality and the major point sources of pollution in this area include mines, industries and very importantly, combined sewage purification works, located alongside the river, which, in addition to oxidizable material contains detergents, nutrients, and metals. It was therefore necessary to determine the extent to which these activities affect the water quality of the system. The impact of these activities was therefore addressed by a Water Research Commision Project namely "Lethal and sublethal effects of metals on the physiology of fish" of which the present study investigated effects at two localities, namely in the Olifants River (locality OR1) before its confluence with the Klein Olifants River and a locality in the Klein Olifants River (locality KOR1). Apart from the field study, toxicity tests were also performed in a laboratory, in order to determine the effects of low pH and elevated aluminium concentrations on the haematology, osmoregulation and carbohydrate metabolism of the Mozambique Tilapia, Oreochromis mossambicus as the acidification of soil systems may cause the transfer of aluminium into aqueous solutions, where it may be present in different forms. During the field study, the chemical and physical characteristics of the river water were evaluated, with special attention to the concentrations of certain metals (manganese, copper, chromium, lead, nickel, zinc, iron and aluminium) in the water and sediment, as well as in fish, which are known to accumulate the elements supra and are therefore valuable as indicators of these pollutants. The two fish species used for the investigations were the African sharptooth catfish, Clarias gariepinus and the moggel, Labeo umbratus. Four tissue types were dissected, namely the muscle, liver, skin and gill tissues. The metal concentrations in these organs/tissues, as well as in the water and sediment, were determined in a laboratory with an atomic absorption spectrophotometer. Statistical analyses were performed on the results obtained from this study and the order and extent of bioaccumulation of these metals in the water and sediment were determined, as well as in the fish organs/tissues. Its dependence on the size, sex and species of the fish and the localities and seasons were investigated.

Ph.D. / Members of Cichlidogyrus are monogenean ectoparasites occurring on the gill filaments of mainly cichlid fishes. An overview of the taxonomic background of the genus and motivation for the study is provided. In this study, existing information on their distribution is organised in a comprehensive table which includes 85 species, their taxonomic authors, hosts and localities from which they have been recorded. Representatives of this genus occur mainly in Africa, but have been found on cichlids as far as Mexico. Host specificity of members of the group is discussed. During the present investigation specimens of the genus Cichlidogyrus were found parasitising Pseudocrenilabrus philander philander, in the Padda Dam in Johannesburg, Gauteng, South Africa. Specimens were examined and identified as Cichlidogyrus philander, previously described from the same host, from Lake Kariba, in Zimbabwe. The morphology was studied utilizing light – and scanning electron microscopy. Specimens were stained with Horen‟s trichrome and photographed. Furthermore 100 whole mounted specimens, which were fixed and mounted in glycerine-ammonium-picrate, were measured. Larval specimens, and mature individuals with eggs in situ, were examined. The investigation of the ecology entailed monthly surveys during which a total of 245 fish specimens were collected with the aid of hand nets, over a period of 14 months (from March 2006 to June 2007). The fish were transported to the laboratory and killed by severing the spinal cord. Gills of specimens of P. p. philander (111), Gambusia affinis (105), Tilapia sparmanii (28) and one (1) 2 specimen of Cyprinus carpio were inspected, for the presence of monogeneans, with the aid of a dissection microscope. Only members of P. p. philander were parasitised by C. philander, indicating strict host specificity. The number of specimens varied from 0 to 184 per fish. The highest mean intensity of 91.6 occurred in the winter month of June 2007, although no significant correlation between season and the occurrence of this parasite was recorded. The prevalence was 100 % for ten of the fifteen surveys and no preference for host sex was recorded. The intensity of the infection correlates positively to the total length of the host, i.e. larger hosts harbour more worms. A positive correlation between condition factor and the total number of worms was found, indicating that more parasites are found on fish with a normal condition factor. No significant difference occurred between the numbers of parasites collected from gill arches on the left or right sides of fish. Statistical analysis of data showed that parasites disperse across the four gill arches with a higher proportion of parasites on the third and second gill arch. The highest proportion of the collected parasites occurred on the dorsal regions and on the distal ends of the gill filaments. Water quality variables do not significantly correlate to the prevalence, abundance or mean intensity of this parasite. This is the first ecological study conducted on specimens of C. philander, worldwide.

Made available in DSpace on 2016-01-26T18:55:35Z (GMT). No. of bitstreams: 1 Alini Soriano.pdf: 205994 bytes, checksum: 47ab15d5ec56c365d78a16b0973e250d (MD5) Previous issue date: 2012-09-27 / The toxocariasis is a disease of worldwide distribution, caused by nematodes Toxocara canis and T. cati, parasites whose definitive hosts are dogs and cats, respectively. These agents can also infect humans, and their larvae can migrate through the body, causing the syndrome of visceral larva migrans (visceral toxocariasis) or ocular (ocular toxocariasis). Consumption of raw or undercooked meat of animals such as ruminants and poultry has been considered as one of the routes of transmission of the disease to humans. Evaluation of the migration of larvae Toxocara spp. in fish is scarce in the literature. This study aimed to evaluate the ability of Toxocara canis to infect and migrate through the tissues of experimentally infected fish. Forty-nine Nile tilapia (Oreochromis niloticus, Linnaeus 1757) were evaluated. Two groups were formed for the assessment of infection. Group I consisted of 35 animals infected by oral gavage with 1,000 T. canis-embryonated eggs (IG). The second group contained 14 animals that received 1.0 ml PBS by oral gavage and served as a control group (CG). To recover the larvae, 5 animals from IG and two animals from CG were euthanised at 1, 2, 5, 10, 15, 30 and 60 days post-infection. Samples of the liver, brain, gills, muscle and intestinal content were collected and subjected to acid digestion and the modified Baermann method. There were no T. canis larvae detected at any time point during this experiment, but embryonated eggs were found in the intestinal contents. Our findings suggest that tilapia could serve as a disseminating vehicle of Toxocara spp. in aquatic environments. / A toxocaríase é uma doença de distribuição mundial, causada pelos nematódeos Toxocara canis e T. cati, parasitos cujos hospedeiros definitivos são os cães e os gatos, respectivamente. Esses agentes podem também infectar seres humanos, e suas larvas podem migrar pelo organismo, ocasionando a síndrome de larva migrans visceral (toxocaríase visceral) ou ocular (toxocaríase ocular). O consumo de carne crua ou mal cozida de animais, como ruminantes e aves, tem sido considerado como uma das vias de transmissão da doença para o ser humano. A avaliação da migração de larvas de Toxocara spp. em peixes é escasso na literatura. Com objetivo de criar um modelo experimental e avaliar a viabilidade da infecção e migração tecidual de Toxocara canis em peixes, foram utilizadas 49 tilápias (Oreochromis niloticus), com peso aproximado de 100 a 150 g, obtidas de uma central de piscicultura. Dois grupos foram formados para avaliação da infecção. O Grupo I (GI) composto por 35 animais infectados oralmente, por gavagem, com 1000 ovos larvados de T. canis diluídos em 1,0 mL de solução salina tamponada (PBS pH 7,0). O segundo grupo (GII) constituído por 14 animais, que receberam, pela mesma via, 1,0 mL de PBS, e serviram como controle. Os peixes foram mantidos em caixas plásticas, com fluxo de água contínuo, e alimentados com ração comercial para peixes duas vezes/dia. Nos dias 1, 2, 5, 10, 15, 30 e 60 pós-infecção, cinco animais do GI e dois do GII foram sacrificados, e amostras de fígado, sistema nervoso central, arcos branquiais, musculatura (filé) e o conteúdo intestinal foram coletados e submetidos ao processo de digestão em ácido clorídrico 0,5% e ao método de Baermann, modificado, para recuperação das larvas. Não foram encontradas larvas de T. canis em nenhum dos momentos deste experimento. No conteúdo intestinal, foram encontrados ovos larvados (5 ovos em média), em todas as tilápias infectadas. Os ovos de T. canis podem ser dispersados no ambiente aquático pela tilápia.