No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

<p>This thesis deals with physical factors and biological interactions affecting the distribution of two fucoid species, <i>Fucus vesiculosus</i> and <i>F. serratus</i>, in the Baltic Sea. Studies have been carried out in two quite different environments: an archipelago, and an open rocky coast. The archipelago has an extremely long coastline with a heterogeneous submerged landscape of different substrate types, slopes, water qualities, and degrees of wave exposure. The factors influencing<i> F. vesiculosus</i> distribution, morphology and epiphyte composition were studied in the Stockholm archipelago using field surveys and spatial modelling in Geographic information systems (GIS). A GIS-method to estimate wave exposure was developed and validated by comparing the result to an index based on vertical zonation of lichens. Wave exposure was considered an important factor for predicting the distribution of <i>F. vesiculosus </i>by its ability to clean hard surfaces from silt, and a predictive model was constructed based on the information of wave exposure and slope of the shore. It is suggested that the lower distribution boundary of attached <i>F. vesiculosus</i> is set by sediment in sheltered parts of the archipelago, and by light availability in highly wave exposed parts. The morphology of <i>F. vesiculosus</i> was studied over a wave exposure gradient, and several characters responded in accordance with earlier studies. However, when separating effects of wave exposure from effects of other confounding water property parameters, only thallus width was significantly different. Several water property parameters were shown to be correlated with wave exposure in the Stockholm archipelago, and the mechanism responsible for the effects on <i>F. vesiculosus</i> morphology is discussed. The composition of epiphytes on <i>F. vesiculosus</i> varied over a wave exposure gradient with a positive correlation to <i>Elachista fucicola</i>, and a negative to <i>Chorda filum</i>. </p><p>At an open coast the physical environment is much less heterogeneous compared to an archipelago. The distributions of <i>F. vesiculosus</i>, <i>F. serratus</i>, turf-forming algae, and the seafloor substrate, were surveyed along the open coasts of Öland and Gotland. Turf-forming algae dominated all hard substrates in the area, and <i>Polysiphonia fucoides</i> was most abundant. At the Gotland coast <i>F. vesiculosus</i> was less abundant than at the Öland coast, and <i>F. serratus</i> occurred only in the southern-most part. <i>Fucus serratus </i>was increasingly more common towards south which was interpreted as an effect mainly of the Baltic salinity gradient, or the variation of salinity that has occurred in the past. The effects of turf-forming algae and sediment on <i>F. serratus</i> recruitment at 7 m depth off the Öland east coast were studied in the field, and by laboratory experiments. Almost no recruits were found in the algal turf outside the <i>F. serratus</i> patches. More fine sediment was found in the turf than in the <i>F. serratus</i> patches, suggesting that the turf accumulates sediment by decreasing resuspension. Both filamentous algae and sediment decreased the attachment ability of <i>F. serratus</i> zygotes and survival of recruits, and sediment had the strongest effect. It is therefore suggested that <i>F. serratus</i> has difficulties recruiting outside its patches, and that these difficulties are enforced by the eutrophication of the Baltic Sea, which has favoured growth of filamentous algae and increased sedimentation. An overall conclusion is that <i>Fucus</i> distribution is affected by large-scale-factors, such as the eutrophication and salinity changes of the Baltic Sea, as well as by small-scale variation in wave exposure, substrate and slope, and by surface competition with neighbouring species. </p>

Gonolobus Michx. (Apocynaceae: Asclepiadoideae) is a New World genus comprising an estimated 100?150 species. The degree of variation in estimated species numbers is largely the result of still poorly known tropical taxa and differences regarding generic limits. Characters historically used to delimit genera such as Gonolobus within Gonolobinae?such as laminar dorsal anther appendages and various follicle morphologies?have been controversial and their evolution remains unknown, not having been explored in a phylogenetic framework. The primary objectives of the current research were to (1) test the monophyly of Gonolobus in the context of a phylogeny of New World Asclepiadeae and (2) explore the evolution of laminar dorsal anther appendages and winged follicles with respect to their potential utility in generic circumscription. Secondary objectives were to revise a tractable monophyletic group as borne out by the phylogenetic analyses and to provide typifications and new combinations as appropriate for Gonolobinae in the West Indies (ca. 50 spp.). Evidence from the chloroplast (trnL-F, rps16) and nuclear genomes (Leafy) presented here supports the monophyly of both the subtribe and the genus Gonolobus in a narrow or broad sense. A transversion in the trnL-F spacer is shown synapomorphic for Gonolobus s.s. Two indels in Leafy, as well as winged follicles, are shown synapomorphic for Gonolobus s.l. Several earlier subgeneric circumscriptions in Matelea, including Ibatia, Heliostemma, Pachystelma, and Ptycanthera, are not monophyletic. Considering the support for a monophyletic Gonolobus s.s., recent taxonomic changes in West Indian taxa, and that several species have been published from the area since the last comprehensive treatment over a hundred years ago, a revision of the genus in the West Indies seemed appropriate and is provided. An index of names and typifications for Gonolobinae in the West Indies is also provided, including numerous lecto- and neotypifications. Twelve new species are described for the West Indies (5 Gonolobus spp., 5 Matelea spp.) and South America (2 Matelea spp.).