The evolution of shell form in tropical terrestrial microsnails

Mollusca form an important animal phylum that first appeared in the Cambrian, and today is,after Arthropoda, the second largest animal phylum, with more than 100,000 extant species(Bieler, 1992, Brusca and Brusca, 2003), with the class Gastropoda accounting for 80% of the extant species in the Mollusca. Despite its species-richness, a generalised gastropod shell architecture is maintained because of conserved developmental processes. All of the shelled gastropods grow by adding, in a unidirectional accretionary way, shell material with the mantle edge organ, usually at different deposition rates around the existing aperture. This shell ontogeny, or to be more specific aperture ontogeny, gives the general spiral form for the shells. However, spiral forms can vary when there are changes in any one of the aspects in the aperture ontogeny profiles, namely, the rate and direction of shell deposition around the aperture, size and shape of the aperture (i.e. mantle edge), and the total length of the shell ontogeny processes. The interplays between these developmental parameters have generated a great diversity in shell form, for which taxonomists and evolutionary biologist are now trying to accurately characterise and to understand with regard to its evolution.This thesis reveals several hitherto unknown aspects of Plectostoma shell forms,in terms of the developmental homology, the aperture ontogeny profile, anti-predation functionality, and evolutionary pattern in shell characters and ontogenetic morphospace evolution. In fact, these are the issues that have been targeted by biologists for centuries in order to improve the way shell shape is characterised and to improve understanding of shell form evolution.he research presented in this thesis was supported by the Netherlands Organization for Scientific Research (NWO, grant no. 819.01.012).UBL - phd migration 201

A Comparative Study of the Evolution of Mammalian High-Frequency Hearing and Echolocation

PhDThe lineage that gave rise to mammals split from other basal amniotes, approximately 300 million years ago. Since then, mammals have evolved many sensory novelties, including high-frequency hearing and echolocation. Sensitivity to high frequencies is particularly well developed in many echolocating mammals; for example, the upper hearing limit of several laryngeal echolocating bat species are estimated to be approximately ten times that of humans. In order to process the high frequency sounds produced during echolocation, the inner ears of laryngeal echolocating bats have undergone substantial modifications. Despite the evolutionary significance of laryngeal echolocation, it is unknown how many times it evolved within bats. Its occurrence on most, but not all, bat lineages suggests it either evolved once with secondary loss, or independently on multiple lineages. Distinguishing between these possibilities is complicated by morphological diversity and convergence. Furthermore, the genetic basis underpinning echolocation remains largely unknown. To elucidate the evolutionary history of this key trait in bats, a combined molecular and morphological approach was taken. Firstly, for two mammalian ‘hearing genes’ sequence convergence, phylogenetic signal and selection pressures were examined across echolocating and non-echolocating mammal species. Secondly, substitution rates of Conserved Non-coding Elements associated with genes regulating ear development were compared across mammals. Finally, as mammalian inner ear development is controlled by many genes, the gross structure of the bony labyrinth was studied in order to examine the combined genetic effect. Structural variation of bat cochleae and vestibular systems was examined using micro-computed tomography reconstructions, and related to ecological data. Subsequent analyses found evidence of convergence at the molecular level, in terms of amino acid substitutions, and also the morphological level, in terms of inner ear morphology. No evidence of degeneration, supporting loss-of-function in Old World fruit bats was found. Conversely, evidence of differential evolution pressures acting on the two echolocating bat lineages was found, which supports multiple origins of laryngeal echolocation in bats.NERC; CRF; CEE; SRF; Teeling lab

Molecular Techniques Reveal Wide Phyletic Diversity of Heterotrophic Microbes Associated with Discodermia spp. (Porifera: Demospongiae)

Sponges are well known to harbor large numbers of heterotrophic microbes within their mesohyl. Studies to determine the diversity of these associated microbes have been attempted for only a few shallow water species. We cultured various microorganisms from several species of Discodermia collected from deep water using the \u27Johnson-Sea-Link\u27 manned submersibles, and characterised them by standard microbiological identification methods. Characterisation of a small proportion (ca. 10%) of the total and potential eubacterial isolate collection with molecular systematics techniques revealed a wide diversity of microbes. Phylogenetic analyses of 32 small subunit (SSU) 16S-like rRNA gene sequences from different micorbes indicated high levels of taxonomic diversity assoiated with this genus of sponge. For example, bacteria from at least five cubacterial subdivisions - gamma, alpha, beta, Cytophaga and Gram positive - were isolated from the mesohyl of Discodermia. Several strains were unidentifiable from current sequence databases. No overlap was found between sequences of 24 isolates and 8 sequences obtained by PCR and cloning directly from sponge samples. The abundance and diversity of microbes associated with sponges such as Discodermia suggest that they may play important roles in marine microbial ecology, dispersal and evolution

Lack of Chemical Defense in Two Species of Stalked Crinoids: Support for the Predation Hypothesis for Mesozoic Bathymetric Restriction

Methanol/dichloromethane extracts of (1) the arms and pinnules, and (2) the stalk and cirri of the deep water stalked crinoids Endoxocrinus parrae (Gervais) and Neocrinus decorus (Carpenter) were imbedded at ecologically relevant volumetric concentrations in alginate food pellets containing 2% krill as a feeding stimulant and presented in situ to an assemblage of shallow-water reef fish. Experimental pellets were highly palatable to reef fish; no significant differences in pellet consumption occurred between experimental pellets containing extracts from either species of stalked crinoid or control pellets. Small pieces of cirri, stalks, calyx, arms and pinnules of both species were also tested in in situ feeding assays. While immediate consumption by fish was not apparent, Blue Headed Wrasse (Thalassoma bifasciatum (Block)) and Dusky Damselfish (Stegastes fuscus (Cuvier)) bit at pieces of each body component. Similar fish biting behaviors were also observed when two living Endoxocrinus parrae were deployed on the shallow reef. Observations indicate that neither species of stalked crinoid is chemically defended from predation by a natural assemblage of reef fish. This supports the predation hypothesis that restriction of stalked crinoids in deep-water habitats may have resulted from the Mesozoic radiation of durophagous fishes in shallow seas, resulting in a reduction of stalked crinoids from shallow water

Habitats and Biota of the Gulf of Mexico: Before the Deepwater Horizon Oil Spill: Volume 1: Water Quality, Sediments, Sediment Contaminants, Oil and Gas Seeps, Coastal Habitats, Offshore Plankton and Benthos, and Shellfish

environmental management; marine; freshwater science

Habitats and Biota of the Gulf of Mexico: Before the Deepwater Horizon Oil Spill: Volume 1: Water Quality, Sediments, Sediment Contaminants, Oil and Gas Seeps, Coastal Habitats, Offshore Plankton and Benthos, and Shellfish

environmental management; marine; freshwater science

Infrastructural Dramaturgy and the Politics of Disability Art and Performance

This dissertation draws on performance studies, critical disability studies, and critical infrastructure studies scholarship to investigate the infrastructural politics of contemporary disability performance. Throughout, I show how disability performance enacts modes of infrastructural inversion that reveal the politics and ideologies embedded within built, interpersonal, and administrative infrastructures. These inversions highlight how infrastructures provide uneven forms of support across different populations and contexts. I also illustrate the potential of disability performance to reimagine inequitable infrastructures in service of a more inclusive, accessible, sustainable, and just worlda world that enables disabled bodyminds and disability culture to flourish. This dissertation presents a series of case studies that closely analyze works of disability performance and explore how these performances intersect with infrastructures in both theatrical and quotidian contexts. To conduct these analyses, I develop a methodology of infrastructural dramaturgy; an approach that mobilizes the analytical potential of dramaturgy and critical infrastructure studies to emphasize infrastructural elements by attending to the context and composition of a performance. Using the lens of infrastructural dramaturgy, this dissertation engages with works like Alex Bulmers May I Take Your Arm?, Kinetic Lights DESCENT, and Hanna Cormicks The Mermaid, among others, to investigate the infrastructural politics of sites and practices including sidewalks, access ramps, administrative protocols, and ways of organizing time. Ultimately, in this dissertation I surface the politics, priorities, and value systems embedded within infrastructures and query how they could be altered to better support disabled bodyminds and disability culture. I also illustrate how disability performance is a form of world building that can imagine and materialize worlds that are rooted in the tenets of equity, interdependence, and ethical care

Infrastructural Dramaturgy and the Politics of Disability Art and Performance

This dissertation draws on performance studies, critical disability studies, and critical infrastructure studies scholarship to investigate the infrastructural politics of contemporary disability performance. Throughout, I show how disability performance enacts modes of infrastructural inversion that reveal the politics and ideologies embedded within built, interpersonal, and administrative infrastructures. These inversions highlight how infrastructures provide uneven forms of support across different populations and contexts. I also illustrate the potential of disability performance to reimagine inequitable infrastructures in service of a more inclusive, accessible, sustainable, and just world—a world that enables disabled bodyminds and disability culture to flourish. This dissertation presents a series of case studies that closely analyze works of disability performance and explore how these performances intersect with infrastructures in both theatrical and quotidian contexts. To conduct these analyses, I develop a methodology of infrastructural dramaturgy; an approach that mobilizes the analytical potential of dramaturgy and critical infrastructure studies to emphasize infrastructural elements by attending to the context and composition of a performance. Using the lens of infrastructural dramaturgy, this dissertation engages with works like Alex Bulmer’s May I Take Your Arm?, Kinetic Light’s DESCENT, and Hanna Cormick’s The Mermaid, among others, to investigate the infrastructural politics of sites and practices including sidewalks, access ramps, administrative protocols, and ways of organizing time. Ultimately, in this dissertation I surface the politics, priorities, and value systems embedded within infrastructures and query how they could be altered to better support disabled bodyminds and disability culture. I also illustrate how disability performance is a form of world building that can imagine and materialize worlds that are rooted in the tenets of equity, interdependence, and ethical care

Science-based restoration monitoring of coastal habitats, Volume Two: Tools for monitoring coastal habitats

Healthy coastal habitats are not only important ecologically; they also support healthy coastal communities and improve the quality of people’s lives. Despite their many benefits and values, coastal habitats have been systematically modified, degraded, and destroyed throughout the United States and its protectorates beginning with European colonization in the 1600’s (Dahl 1990). As a result, many coastal habitats around the United States are in desperate need of restoration. The monitoring of restoration projects, the focus of this document, is necessary to ensure that restoration efforts are successful, to further the science, and to increase the efficiency of future restoration efforts