The biology of malaria parasites, Plasmodium spp., may be influenced by the presence of genetically distinct conspecific clones within a single infection, resulting in competition for host resources and transmission, and increased virulence for the vertebrate host. The extent of within host diversity, however, may be limited because overall clonal diversity could be reduced by the transmission biology of Plasmodium and variation in local prevalence. I examined clonal diversity of a natural malaria parasitehost association, P. mexicanum in its hosts, the western fence lizard, Sceloporus occidentalis, and sandflies, Lutzomyia vexator and L. stewarti, at a site in California ("Hopland"). Using microsatellite markers I characterized for the parasite, I examined (i) diversity within and among infections over time and space, (ii) transmission success of clones into both vector and lizard, (iii) the effects of clonal diversity on the parasite's infection dynamics and virulence for the lizard. From 1996 to 2006, clonal diversity varied both temporally and spatially, with slightly more multiclonal infections detected during years of high vs. low parasite prevalence (88% vs. 78% for sites with the highest prevalence at Hopland). Spatially, low prevalence sites (< 1% of lizards infected) had fewer multiclone infections (50%). Thus, even when prevalence drops over time, or at sites with chronically low prevalence, clonal diversity of the parasite remains high. Using natural and induced infections in the lizard, I found that multiclonal infections are no more infectious to vectors than single-clone infections, and almost all clones transfer successfully when the insect takes a blood meal. A competition experiment demonstrated that infections block new genotypes from entering a lizard host. Thus, multiclone infections are likely to be established when vectors feed on a complex infection and transmit those parasite clones to an uninfected lizard. The transmission biology of Plasmodium thus allows for the maintenance of genetic diversity in the parasite population. Finally, I examined the effects of multiclonality on the parasite's infection dynamics and virulence to the lizard host. Induced infections harboring a single or multiple clones had similar overall growth rates and maximal parasitemia, but multiclonal infections had significantly higher investment in gametocytes, suggesting competition for transmission. In addition, variation in parasite growth and density was greater for multiclonal infections, with approximately 1/3 displaying high replication rates and final parasitemia. Virulence measures indicated that weight change and proportion of immature erythrocytes was consistent for infections with 1, 2, 3 or > 3 clones, but the highly diverse infections had greater blood hemoglobin and glucose and more rapid clotting rates. Compared with the noninfected control lizards, highly diverse infections (3+) had higher blood glucose levels but similar hemoglobin levels. I have found that genetic diversity of the malaria parasite Plasmodium mexicanum varies both temporally and spatially, although overall diversity remains high. The transmission dynamics of the parasite maintains high genetic diversity within infections. Additionally, diversity within hosts plays a significant role in variation of infection dynamics and virulence.

Canyon shaped reservoirs are characteristic by specific environmental horizontal gradients, so they enable existence of several species of the Daphnia longispina complex in one water body. Due to preference of distinct environmental conditions Daphnia species occurre in the different localities. The aim of my thesis was to analyze detail taxonomical and clonal structure of Daphnia longispina group by ten microsatellite markers on longitudinal gradient and compare it between two consecutive seasons. Simultaneously I received newly discovered divergent mitochondrial lineage from Želivka reservoir. It was confirmed, that the distribution of species and their hybrids in water reservoir was non-concidental and the taxonomic spatial distribution is in two consecutive seasons relatively constant. On the contrary the spatial and temporal distribution of clones was very heterogeneous. Clonal diversity in the interspecific hybrids was lower than in the coexisting parental species. This finding supports the hypothesis, that there exist reproductive barriers between parental genomes. Most of the clones were substantively variable, but several clones that occurred in both seasons in similar localities were found. It is possible that some clones are able of overwintering in hypolimnion and in the spring...

The Florida Keys National Marine Sanctuary (FKNMS) encompasses North America's only living coral barrier reef and the third longest barrier reef in the world, making it a unique national treasure of international notoriety (FKNMS, 2005). Recent evidence of environmental decline within the sanctuary has created a sense of urgency to understand and protect the valuable resources within. This thesis contributed to the understanding of habitat connectivity to aid managers and decision makers in the creation of additional Marine Protected Areas (MPAs) in the FKNMS to help prevent further environmental decline. This research specifically focused on modeling larval transport and larval connectivity among Acropora palmata (Lamarck, 1816) populations, coral habitats and MPAs in the upper and middle FKNMS. The transport of larvae in relation to ocean currents is a very limited area of research, and the analytic modeling results may serve as powerful guides to decisions about the relative importance of individual coral habitats and MPAs in the study area.Larval transport was modeled with ArcGIS and TauDEM using SoFLA-HYCOM simulated ocean currents during the A. palmata spawning season. This model allowed for the assessment of coral habitat and A. palmata population larval connectivity. The dependence of three distant A. palmata test populations on other upstream coral habitats and A. palmata populations significantly differed (Kruskal-Wallis test, P less than 0.0001). The clonally diverse Sand Island Reef A. palmata population's larval connectivity was significantly higher compared to other distant monoclonal populations (Mann-Whitney test, P less than 0.0001). Compared to the clonal structure of each test population determined by Baums, Miller, and Hellberg (2006), results indicated simulated larval connectivity may be a determinant of A. palmata population clonal diversity.By modeling MPA and coral habitat connectivity, this study also identified unprotected and distant coral habitat areas with the greatest downstream influence on MPAs; these may serve as potential coral larvae sources. It is recommended that establishing these areas as no-take MPAs would improve overall coral habitat and MPA network connectivity.

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