Fylogenetická diverzita rodu Phyllosiphon (Trebouxiophyceae, Chlorophyta) v Evropě

Rod Phyllosiphon (Trebouxiophceae) zahrnuje unikátní a málo známé fototrofní želené řasy, které vytvářejí endofytní sifonální stádia uvnitř zástupců čeledi Araceae. Dosud bylo popsáno šest parazitických druhů rodu Phyllosiphon z listů áronovitých rostlin, avšak jediné známé DNA sekvence byly získány z P. arisari, druhu, který napadá listy Arisarum vulgare rostoucí ve Středomoří. Environmentální sekvence blízce příbuzné s těmi získanými z P. arisari byly překvapivě nedávno objeveny ve vzorcích fototrofních biofilmů rostoucích na pískovcových substrátech v Německu a Severním Irsku. Tyto studie však neposkytly žádné informace o morfologii těchto řas. V této práci jsem hledala parazity rodu Phyllosiphon v listech suchozemských zástupců Araceae rostoucí v mediteránní Evropě za účelem zjištění, zda jsou parazitické řasy rodu Phyllosiphon izolované z různých taxonů čeledi Araceae fylogeneticky odlišené, anebo vytvářejí jednu linii uvnitř Watanabea kladu z třídy Trebouxiophyceae. Kromě toho byly odebrány vzorky kortikoidních biofilmů z různých lokalit v Evropě, s cílem zaznamenat přítomnost buněk rodu Phyllosiphon mimo jejich hostitele. Parazitické stélky a chlorelloidní stádia rodu Phyllosiphon izolované z kortikolních biofilmů byly kultivovány za úřelem pochopení jejich životních cyklů. Jednořasové...Abstact The trebouxiophycean genus Phyllosiphon includes unique and little known phototrophic green algae that form endophytic siphonous stages within the members of Araceae. In total, six parasitic species of the genus Phyllosiphon were originally described from the leaves of Araceae, but the only known DNA sequences were acquired from P. arisari, a species that infects leaves of Arisarum vulgare growing in the Mediterranean region. Surprisingly, the environmental sequences closely related to those obtained from P. arisari were recently detected in samples of phototrophic biofilms thriving on sandstone substrates in Germany and Northern Ireland. However, these studies did not provide any information about morphology of these microalgae. In this thesis, I was looking for Phyllosiphon parasites in the leaves of terrestrial members of the Araceae growing in the Mediterranean Europe in order to find out whether parasitic algae of the Phyllosiphon isolated from different taxa of the Araceae are phylogenetically differentiated, or they form a single lineage within the Watanabea clade of Trebouxiophyceae. In addition, corticolous biofilms from various localities in Europe were sampled in order to detect any presence of Phyllosiphon cells outside their hosts. Both the parasitic thalli and chlorelloid unicells of...Katedra botanikyDepartment of BotanyPřírodovědecká fakultaFaculty of Scienc

The influence of isolation on the dynamics of populations and communities

Isolation is defined as the separation in time or space of individuals, populations, or of species within a community. Though isolation can be the result of many ecological processes, its role in affecting the structure and dynamics of populations and communities is not often acknowledged directly. For example, spatial heterogeneity is a frequently recognized as a significant ecological factor, but the effects of spatial heterogeneity are manifested through the isolation that heterogeneity imposes on the focal populations or communities. Isolation is an important, but hidden, component of many other ecological theories and frameworks as well. In this dissertation, I explore the role of isolation per se as an organizing theme in ecology by studying the effects of isolation in time and in space on both populations and communities. Chapter 1 explores how isolation in time among individuals in a population may affect the population's dynamics and risk of extinction. Through a combination of modeling and meta-analysis, Chapter 1 demonstrates that reproductive asynchrony, a form of temporal isolation, can have profound negative effects at the population level in species that feature annual lifecycles. Chapter 2 reviews and synthesizes the literature on habitat connectivity, the inverse of spatial isolation, and lays out a novel framework for organizing and understanding the different metrics used to measure the connectivity. Chapter 3 examines the role of spatial isolation among species in an assemblage of Costa Rican bark beetles in mediating species interactions. The chapter uses a combination of modeling and field-collected observational data to test the hypothesis that isolation among species in this bark beetle assemblage results in a community that behaves neutrally. The studies presented in this dissertation represent a broad sweep of the ways in which the concept of isolation may be applied to better understand the dynamics of populations and communities. Individually, each chapter is an original contribution to the ecology literature. Taken together, these papers demonstrate the power of isolation as an organizing theme in ecology and will hopefully stimulate increased research effort and theoretical development around the concept of isolation

Phylogenetic study in the "Rhizocarpon geographicum" group (Lichens, Rhizocarpaceae, Ascomycota). Contrasting analysis of morphological characters and biogeographic patterns

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Farmacia, Departamento de Biología Vegetal II, leída el 26/04/2013Depto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEunpu

Use of Bomb-14C to investigate the growth and carbon turnover rates of a crustose lichen

The reliability of lichenometric dating is dependent on a good understanding of lichen growth rates. The growth rate of lichens can be determined from direct measurement of growing lichens or indirect methods by measuring lichens growing on surfaces of known age, although there are limitations to both approaches. Radiocarbon (14C) analysis has previously been used in only a handful of studies to determine lichen growth rates of two species from a small area of North America. These studies have produced mixed results; a small amount of carbon turnover appears to occur in one of the species (Caloplaca spp.) previously investigated introducing uncertainty in the growth rate, while much higher carbon cycling occurred in another (Rhizocarpon geographicum), making the 14C approach unsuitable for estimating growth rates in the species most commonly used in lichenometric dating. We investigated the use of bomb-14C analysis to determine the growth rate of a different crustose species (Pertusaria pseudocorallina) common to Northern Europe. 14C-based growth rates were considerably higher than growth rates of morphologically similar species based on direct measurement made at locations nearby and elsewhere in the UK. This observation strongly suggests that a degree of carbon turnover probably occurs in Pertusaria pseudocorallina, and that bomb-14C analysis alone cannot be used to determine lichen age or absolute growth rates in this lichen species

Growth of crustose lichens : a review

Crustose species are the slowest growing of all lichens. Their slow growth and longevity, especially of the yellow-green Rhizocarpon group, has made them important for surface-exposure dating (lichenometry). This review considers various aspects of the growth of crustose lichens revealed by direct measurement including: 1) early growth and development; 2) radial growth rates (RGR, mm yr−1); 3) the growth rate–size curve; and 4) the influence of environmental factors. Many crustose species comprise discrete areolae that contain the algal partner growing on the surface of a non-lichenized fungal hypothallus. Recent data suggest that 'primary' areolae may develop from free-living algal cells on the substratum while 'secondary' areolae develop from zoospores produced within the thallus. In more extreme environments, the RGR of crustose species may be exceptionally slow but considerably faster rates of growth have been recorded under more favourable conditions. The growth curves of crustose lichens with a marginal hypothallus may differ from the 'asymptotic' type of curve recorded in foliose and placodioid species; the latter are characterized by a phase of increasing RGR to a maximum and may be followed by a phase of decreasing growth. The decline in RGR in larger thalli may be attributable to a reduction in the efficiency of translocation of carbohydrate to the thallus margin or to an increased allocation of carbon to support mature 'reproductive' areolae. Crustose species have a low RGR accompanied by a low demand for nutrients and an increased allocation of carbon for stress resistance; therefore enabling colonization of more extreme environments