Trygonorrhina fasciata (Rhinobatidae) specimens naturally infected by three monogenean species were captured and maintained in marine aquaria to promote a continuous parasite load. Monogenean eggs recovered from aquaria provided larvae for descriptions and life history experiments. I describe the adult, larva and post-larval development of a new species of hexabothriid, Branchotenthes octohamatus, from the gills. This is the first monogenean larva described with only eight hooklets. This character may be useful to help resolve problematic relationships within the Hexabothriidae and offers insight into more general hypotheses about relationships within the Monogenea. I also redescribe the adult of Calicotyle australis (Monocotylidae) from the cloaca and describe the larva. The number and arrangement of larval ciliated epidermal cells and sensilla was revealed using silver nitrate. I redescribe Pseudoleptobothrium aptychotremae (Microbothriidae) adults from the skin of T. fasciata, representing a new host and locality record. Larval anatomy and post-larval development are also documented. The presence of six needle-like spicules in the larval haptor is confirmed, supporting an earlier theory that spicules are ancestral vestiges. My studies revealed three different egg hatching, host finding strategies and larval ‘types’. Branchotenthes octohamatus has a ‘sit-and-wait’ strategy, entirely dependent on mechanical disturbance to stimulate eggs to hatch. Larvae are unciliated, cannot swim, lack pigmented eyespots and show no photo-response but may survive for more than two days after hatching at 22ºC. In contrast, eggs of C. australis hatch spontaneously with a strong diurnal rhythm in the first few hours of daylight when exposed to a LD12:12 illumination regime. Larvae are ciliated and can swim, have pigmented eyespots, are photo-positive and can remain active and survive for up to 24 h after hatching at 22ºC. Eggs of P. aptychotremae may have a ‘bet-hedging’ strategy. Some eggs hatch spontaneously and rhythmically in an LD12:12 regime during the last few hours of daylight but their low hatching success rate suggests that other eggs may require a different cue provided by the host. Larvae are ciliated, can swim, lack pigmented eyespots, show no photo-response and remain active for only a few hours at 22ºC. Experiments using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) revealed B. octohamatus on gills of T. fasciata within 30 min of exposure to the host. This provides strong evidence that larvae invade the gills directly via the host’s inhalant respiratory current and do not migrate after initial attachment elsewhere. Five rhinobatid species (Aptychotrema vincentiana, T. fasciata, Trygonorrhina sp. A, A. rostrata and Rhinobatos typus), with overlapping distributions spanning west, south and east Australian coastal waters were surveyed for monogeneans at four locations between Fremantle, Western Australia and Stradbroke Island, Queensland. Genetic homogeneity, using the mitochrondrial gene Cytochrome b (cytb) and the nuclear marker, Elongation factor-1 alpha (EF1a), was observed for all Branchotenthes and Calicotyle specimens irrespective of collection locality or rhinobatid species. Genetic homogeneity was observed for Pseudoleptobothrium specimens collected in western and southern Australia. However, local genetic heterogeneity was apparent among Pseudoleptobothrium specimens collected from two sympatric host species in New South Wales. Analyses revealed a highly divergent clade, indicating a morphologically cryptic, ancestral species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1323070 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Trygonorrhina fasciata (Rhinobatidae) specimens naturally infected by three monogenean species were captured and maintained in marine aquaria to promote a continuous parasite load. Monogenean eggs recovered from aquaria provided larvae for descriptions and life history experiments. I describe the adult, larva and post-larval development of a new species of hexabothriid, Branchotenthes octohamatus, from the gills. This is the first monogenean larva described with only eight hooklets. This character may be useful to help resolve problematic relationships within the Hexabothriidae and offers insight into more general hypotheses about relationships within the Monogenea. I also redescribe the adult of Calicotyle australis (Monocotylidae) from the cloaca and describe the larva. The number and arrangement of larval ciliated epidermal cells and sensilla was revealed using silver nitrate. I redescribe Pseudoleptobothrium aptychotremae (Microbothriidae) adults from the skin of T. fasciata, representing a new host and locality record. Larval anatomy and post-larval development are also documented. The presence of six needle-like spicules in the larval haptor is confirmed, supporting an earlier theory that spicules are ancestral vestiges. My studies revealed three different egg hatching, host finding strategies and larval ‘types’. Branchotenthes octohamatus has a ‘sit-and-wait’ strategy, entirely dependent on mechanical disturbance to stimulate eggs to hatch. Larvae are unciliated, cannot swim, lack pigmented eyespots and show no photo-response but may survive for more than two days after hatching at 22ºC. In contrast, eggs of C. australis hatch spontaneously with a strong diurnal rhythm in the first few hours of daylight when exposed to a LD12:12 illumination regime. Larvae are ciliated and can swim, have pigmented eyespots, are photo-positive and can remain active and survive for up to 24 h after hatching at 22ºC. Eggs of P. aptychotremae may have a ‘bet-hedging’ strategy. Some eggs hatch spontaneously and rhythmically in an LD12:12 regime during the last few hours of daylight but their low hatching success rate suggests that other eggs may require a different cue provided by the host. Larvae are ciliated, can swim, lack pigmented eyespots, show no photo-response and remain active for only a few hours at 22ºC. Experiments using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) revealed B. octohamatus on gills of T. fasciata within 30 min of exposure to the host. This provides strong evidence that larvae invade the gills directly via the host’s inhalant respiratory current and do not migrate after initial attachment elsewhere. Five rhinobatid species (Aptychotrema vincentiana, T. fasciata, Trygonorrhina sp. A, A. rostrata and Rhinobatos typus), with overlapping distributions spanning west, south and east Australian coastal waters were surveyed for monogeneans at four locations between Fremantle, Western Australia and Stradbroke Island, Queensland. Genetic homogeneity, using the mitochrondrial gene Cytochrome b (cytb) and the nuclear marker, Elongation factor-1 alpha (EF1a), was observed for all Branchotenthes and Calicotyle specimens irrespective of collection locality or rhinobatid species. Genetic homogeneity was observed for Pseudoleptobothrium specimens collected in western and southern Australia. However, local genetic heterogeneity was apparent among Pseudoleptobothrium specimens collected from two sympatric host species in New South Wales. Analyses revealed a highly divergent clade, indicating a morphologically cryptic, ancestral species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1323070 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Ce travail s’est intéressé aux liens existant entre la stratégie d’exploitation développée par un crustacé ectoparasite et son comportement reproductif. Le crabe Pinnotheridae Dissodactylus<p>primitivus exploite deux espèces Spatangidae vivant dans la Mer des Caraïbes, Meoma<p>ventricosa et Plagiobrissus grandis. Des approches comportementales, démographiques et<p>génétiques ont été adoptées afin de mettre en lumière le fonctionnement et la biologie de cette<p>symbiose. Par son comportement alimentaire, le crabe occasionne des lésions tégumentaires<p>sur ses hôtes. Celles-ci affectent la fitness de M. ventricosa, au travers de son développement<p>gonadique. Dissodactylus primitivus exploite ses deux espèces hôtes de façon asymétrique. La<p>reproduction des parasites se déroule sur les deux hôtes, alors que le recrutement ne s’effectue<p>que sur M. ventricosa. Ce cycle vital asymétrique du crabe serait stabilisé par la qualité et la<p>rareté de P. grandis. En outre, Le comportement sexuel du crabe sur M. ventricosa répondrait<p>aux critères de la polygynandrie à femelles mobiles. Selon ce modèle, les mâles et les<p>femelles se déplacent entre les hôtes à la recherche de partenaires multiples. Lors de ces<p>déplacements, le crabe s’aiderait de son aptitude à localiser chimiquement ses hôtes.<p>Néanmoins, ce mécanisme s’avère plastique et pourrait refléter l’asymétrie du cycle vital. En<p>effet, cette différence n’a pas d’origine génétique, car les crabes vivant au sein du site d’étude constituent la même population quelle que soit l’espèce hôte considérée. Les marqueurs<p>moléculaires microsatellites mis au point dans ce travail permettront lors de futurs travaux<p>d’affiner les observations sur les modalités d’accouplement du crabe et d’estimer sa capacité<p>de dispersion.<p><p>This work aimed to highlight the relationships between the host exploitation strategy of an<p>ectoparasite crustacean and its mating system. The pea crab Dissodactylus primitivus exploits<p>two Spatangidae species living in the Caribbean Sea, Meoma ventricosa and Plagiobrissus<p>grandis. Behavioural, demographic and genetic approaches have been conducted to examine<p>the functioning and biology of this symbiosis. Owing to its feeding behaviour, the crab<p>wounds the host tegument. The wounds negatively affect M. ventricosa's fitness through its<p>gonadic development. Dissodactylus primitivus asymmetrically exploits its two host species.<p>The reproduction of the parasites happens on each host, but the recruitment only takes place<p>on M. ventricosa. The asymmetrical life cycle would be stabilised par the quality and the<p>scarcity of P. grandis. The mating system of crabs living on M. ventricosa would correspond<p>to the Pure-search polygynandry of mobile females criteria. According to this model, the<p>males and the females practice the host switching behaviour to find several sexual partners.<p>During these movements, the crab could use its chemodetection ability to locate its hosts.<p>However, this mechanism is plastic and presumably reflects the asymmetrical life cycle of the<p>crab. This difference has indeed not a genetic cause because the crabs living inside the<p>investigated region belong to the same population, whatever the regarded host species. In<p>future studies, the microsatellites markers developed for this work could be used to test the<p>mating system of D. primitivus and to estimate its dispersion ability. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

L’évolution divergente est un processus clef générant de la biodiversité. Elle peut avoir lieu entre localités, via la réduction des flux de gènes, et au sein des localités via la spécialisation écologique. Dans le cas des systèmes parasitaires multi-hôtes, l’adaptation dépend des taux relatifs de flux de gènes des hôtes et des parasites entre différentes localités, ainsi que des échanges locaux de parasites entre différents types d’hôtes. En combinant génétique des populations et expérimentations sur le système composé de la puce Ceratophyllus gallinae et deux de ses hôtes, la mésange charbonnière Parus major et le gobe-mouche à collier Ficedula albicollis dans un habitat fragmenté, nous avons examiné comment l’adaptation et l’isolation génétique façonnent l’évolution des parasites. Nous avons aussi testé comment les choix d’habitat des hôtes pouvaient influencer la rencontre avec des populations de parasites spécialisées. Les analyses de microsatellites révèlent que les populations de puce sont différenciées à une échelle spatiale fine, et fréquemment entre espèces hôtes. De plus, des populations de parasites semblent adaptées à chaque type d’hôte. Cependant, aucune variation dans les choix d’habitats par rapport aux parasites n’a été observée chez les hôtes. Enfin, la réponse des hôtes aux parasites variait entre nos deux zones réplica ; l’histoire des populations d’hôtes pourrait donc influer sur la coevolution avec leurs parasites. Ce système semble donc localement façonné à la fois par une isolation génétique et une sélection par différents hôtes. L’étude de nouveaux sites permettraient d’évaluer si cette évolution divergente peut être génératrice de biodiversité / Divergent evolution is a key process generating biodiversity. This can occur between localities, through reduced gene flow followed by local adaptation or genetic drift, and within localities through ecological specialization. In the case of multi-host parasite systems, adaptation can be driven by the relative rate of host-parasite gene flow among spatially isolated populations, and the amount of parasite exchange among local host types. Combining population genetics and field experiments, we examined how adaptation and genetic isolation shape parasite evolution. Focusing on the hen flea Ceratophyllus gallinae, a presumed host generalist, and two of its hosts, the great tit Parus major and the collared flycatcher Ficedula albicollis, we investigated parasite population structure and adaptation within a fragmented landscape. Additionally, we tested how hosts can influence encounter rates with specialized flea populations through their habitat choice. Neutral markers analyses show that flea populations are genetically differentiated at fine spatial scales, and frequently between the two host species. Evidence for parasite adaptation to each host type were also observed. Host specialization may therefore be ongoing in hen fleas. However, birds did not show specific habitat choice strategies regarding flea-infested nests. Host responses differed between two replicate sites, indicating that local population history may impact parasite evolution. Both isolation and host-based selection are therefore acting on hen flea populations at a local scale. Investigations in new localities will help to assess to what extend this divergent evolution may generate biodiversity