No description available.

One important source of phenotypic variation on which natural selection can act is developmental plasticity (the capacity of a single genotype to produce different environment-dependent forms). Therefore, studies of how the environment influences development can facilitate our understanding of how natural selection acts to yield phenotypic evolution. Using the Pacific barnacle (Balanus glandula Darwin), I explored how functionally independent appendages (the legs and unusually long penises of barnacles) respond to widespread spatial and temporal variation in water velocity and conspecific density. Through field surveys, reciprocal transplant experiments, and histological sectioning, I show that barnacle legs and penises appear remarkably well adapted to spatial and temporal variation in water velocity. Building on past work on leg form variation, I show that penises from exposed shores were shorter than, stouter than, and more than twice as massive for their length, as those from nearby protected bays (this effect holds true for artificially inflated penises as well). A transplant experiment confirmed that most of this variation in penis and leg form variation was due to developmental plasticity. Penises and legs of barnacles from an exposed shore also had thicker cuticle, and muscles with greater cross-sectional area (and shorter sarcomeres) compared to those from a protected shore. Form variation was consistent with numerous predictions from engineering theory suggesting that barnacles show dramatic, complex and likely adaptive variation in leg and penis form among sites that differ dramatically in water velocity. Additional experiments showed evidence for and against developmental limits to plasticity in barnacles. A transplant experiment identified an important (and asymmetrical) developmental limit to leg-length response time – likely mediated by food limitation – while a field survey showed that developmental coupling does not restrict adaptive plastic responses of legs and penises to multiple conflicting cues (conspecific density and water velocity). Finally, a two-year survey of natural populations revealed the first evidence that barnacles also change leg form seasonally. Together these results contribute valuable information on the mechanisms of phenotypic change. This research also sheds light on the circumstances that allow decoupling of developmental processes to produce novel combinations of characters on which natural selection can act. / Ecology

As the final larval stage before settlement, barnacle cyprids swim with six pairs of thoracic appendages used to maintain orientation, change direction, and swim against downwelling currents. This thesis examines thoracic appendage morphology and swimming behavior in cyprids of Balanus glandula Darwin, 1854. Cyprid swimming appendages carry arrays of plumose setae, unique among crustaceans in that setules of adjacent setae are permanently fused at their tips, creating a webbed setal array. Cyprids are drag-based swimmers, beating appendages sequentially through metachronal strokes during which interconnected arrays act as paddles. Setal arrays spread apart during metachronal power strokes (increasing surface area and drag force of the appendage) and collapse together during synchronous recovery strokes (decreasing surface area and limiting drag). Cyprids move at an average speed of 1.4 cm/sec (with peak speeds of 6 cm/sec) during a beat cycle, with a frequency of 16 beats/sec. This thesis includes previously unpublished co-authored material. / 2019-01-09

No description available.

Biofouling is a significant economic problem, particularly for marine and offshore oil industries. The acorn barnacle (Amphibalanus (Balanus) amphitrite) is the main biofouling organism in marine environments. Environmental conditions, the physiology of the biofouling organism, the surrounding microbial community, and the properties of the substratum can all influence the attachment of biofouling organisms to substrates. My dissertation investigated the biological processes involved in B. amphitrite development and attachment in the unique environment of the Red Sea, where the average water surface temperature is 34°C and the salinity reaches 41‰. I profiled the transcriptome and proteome of B. amphitrite at different life stages (nauplius II, nauplius VI, and cyprid) and identified 65,784 expressed contigs and 1387 expressed proteins by quantitative proteomics. During the planktonic stage, genes related to osmotic stress, salt stress, the hyperosmotic response, and the Wnt signaling pathway were strongly up-regulated, hereas genes related to the MAPK pathway, lipid metabolism, and cuticle development were down-regulated. In the transition from the nauplius VI to cyprid stages, there was up-regulation of genes involved in blood coagulation, cuticle development, and eggshell formation, and down-regulation of genes in the nitric oxide pathway, which stimulates the swimming and feeding responses of marine invertebrates. This system-wide integrated approach elucidated the development and attachment pathways important in B. amphitrite. Enzymes and metabolites in these pathways are potential molecular targets for the development of new antifouling compounds.

The purpose of this study was to determine how two morphs of the acorn barnacle, Chthamalus anisopoma, coexist on rocky intertidal shores in the northern Gulf of California. The test of one of these forms (here called "typical") has the conical, volcano shape which is characteristic of acorn barnacles while the test of the atypical form (here called "bent") grows bent-over so that the plane of the aperture's rim is perpendicular to the substrate. I tested the hypotheses that bents are more resistant than typicals to: (1) desiccation during low tides and (2) attack by a carnivorous snail (Acanthina angelica) involving the use of a labial spine. These two hypotheses (which were suggested from analysis of the distribution patterns of the two morphs) were tested in conjunction with experiments designed to determine whether the bent form is genetically controlled or environmentally induced. The results indicated that the bent-over morph is a developmental response to the presence of A. angelica and that it is more resistant than the typical form to specialized predation by this gastropod. I also tested the hypotheses that: (1) bents are inferior competitors for primary rock space, and (2) the bent-over morphology places constraints on growth and reproduction. I found no evidence to suggest that bents are inferior competitors for space. They were, however, found to grow more slowly than typicals and to brood fewer eggs per unit body size. In summary, the bent-over form of C. anisopoma is a conditional response to the presence of a predator and both the conditional strategy and the dimorphism appear to be maintained by a trade-off between resistance to predation and the ability to convert resources into offspring.

Since their recent introductions into Florida waters, three nonnative species [Perna viridis Linnaeus, 1758 (Asian green mussel), Mytella charruana d'Orbigny, 1846 (charru mussel) and Megabalanus coccopoma Darwin, 1854 (pink titan acorn barnacle)] have expanded both north and south along the Atlantic coast. Very little research has been done to understand how these nonnative species interact with the native eastern oyster (Crassostrea virginica Gmelin, 1791), which is a keystone species that provides important ecological services and economic benefits. To test the potential effects of P. viridis, M. charruana and M. coccopoma on C. virginica, I addressed the following questions: 1a) Does the presence of nonnative species decrease oyster larval settlement? 1b) Do oyster larvae avoid settling on oyster shells to which nonnative species are attached? 2a) Do nonnative species decrease survival of juvenile oysters (spat)? and 2b) Do nonnative species hinder spat growth? My manipulative experiments showed that the tested nonnative species influenced settlement, growth and survival of C. virginica in unique ways. Megabalanus coccopoma decreased the total number of settled oyster larvae, but did not influence larval preference or survival and growth of spat. Perna viridis negatively influenced larval settlement and oyster larvae avoided settling on shells of P. viridis. Mytella charruana had no influence on the total number of settled larvae but oyster larvae avoided settling on oyster shell with M. charruana or on the mussel shells themselves. Furthermore, both nonnative mussels negatively affected the survival of juvenile oysters, but only M. charruana reduced spat growth. These three nonnative species should be classified as invasive species because all had negative effects on the native oyster C. virginica.

Investigations into the supply, settlement and recruitment of the barnacle Semibalanus balanoides (L.) to shores in Fife, East Scotland were undertaken over three consecutive years (2004 – 2006). Several designs of a passive larval trap, based on earlier published designs, were employed to quantify the delivery (supply) of cyprids to the substratum. Pump samples from the water column were collected to provide a measure of intertidal cyprid concentration. Cyprid concentration was found to exhibit both spatial and temporal variation, but was also found to be significantly correlated with cyprid supply, as quantified by the traps. In some years, pump and trap samples suggested that cyprid abundance in the intertidal was mediated by wind-driven processes. An artificial substratum was used to quantify cyprid settlement, allowing investigations into the supply-settlement relationship. Supply and settlement were found to be two very distinct biological phases. Supply describes the flux of larvae to the substratum. Settlement provides a measure of the amount of larvae that decide to settle on the substratum, as initial attachment for barnacle larvae is not permanent. Whilst supply saturation is unfeasible, daily saturation of the substratum by settlers was observed at many sites along the Fife coast. Levels of settlement saturation were found to vary both temporally, between years, and spatially, over scales of km. Varying levels of the desperation of larvae to settle, mediated by dwindling energy reserves, was thought to explain some of this variation. The supply data also provided some evidence of the possible movement of cyprids along the Fife coast from Fife Ness to Tentsmuir. However, wind-induced transport may also play a dominant role on the Fife coast. A comparison of supply and recruitment of larvae into adult populations revealed that both pre- and post-settlement events may influence recruitment. The relative importance of these factors was shown to be density-dependent. Negative intraspecific interactions were only seen in denser aggregations of adults. In less crowded aggregations, recruitment reflected initial patterns of larval supply.

Owing to atomic force microscopy’s (AFM) high-resolution in both imaging and force spectroscopy, it is very successful in probing not only structures, but also nanomechanics of biological samples in solution. In this thesis, the nanomechanical properties of lipid bilayers of biological relevance and proteins of the barnacle adhesive were examined using AFM indentation, AFM-based force mapping, and single-molecule pulling experiments. Through high-resolution AFM-based force mapping, the self-organized structures exhibited in phase-segregated supported lipid bilayers consisting of dioleoylphosphatidylcholine / egg sphingomyelin / cholesterol (DEC) in the absence and presence of ceramide (DEC-Ceramide) were directly correlated with their breakthrough forces, elastic moduli, adhesion, and bilayer thickness. Results were presented as two-dimensional visual maps. The highly stable ceramide-enriched domains in DEC-Ceramide bilayers and the effect of different levels of cholesterol as well as of diblock copolymers, on the nanomechanical stability of the model systems studied were further examined. For the proteins of the barnacle adhesive, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and chemical staining with amyloid-selective dyes, in addition to AFM imaging, indentation, and pulling experiments were performed to study the structure and nanomechanics of the polymerized barnacle glue. Nanoscale structures exhibiting rod-shaped, globular, and irregularly shaped morphologies were observed in the bulk barnacle cement by AFM. SEM coupled with energy dispersive x-ray (EDX) makes evident the organic nature of the rod-shaped nanoscale structures while FTIR spectroscopy on the bulk cement gave signatures of β-sheet and random coil conformations. Indentation data yielded higher elastic moduli for the rod-shaped structures as compared to the other structures in the bulk cement. Single molecule AFM force-extension curves on the matrix of the bulk cement often exhibited a periodic sawtooth-like profile, observed in both extend and retract portions of the force curve. Rod-shaped structures stained with amyloid protein-selective dyes (Congo Red and Thioflavin-T) revealed that about 5% of the bulk cement are amyloids.

Owing to atomic force microscopy’s (AFM) high-resolution in both imaging and force spectroscopy, it is very successful in probing not only structures, but also nanomechanics of biological samples in solution. In this thesis, the nanomechanical properties of lipid bilayers of biological relevance and proteins of the barnacle adhesive were examined using AFM indentation, AFM-based force mapping, and single-molecule pulling experiments. Through high-resolution AFM-based force mapping, the self-organized structures exhibited in phase-segregated supported lipid bilayers consisting of dioleoylphosphatidylcholine / egg sphingomyelin / cholesterol (DEC) in the absence and presence of ceramide (DEC-Ceramide) were directly correlated with their breakthrough forces, elastic moduli, adhesion, and bilayer thickness. Results were presented as two-dimensional visual maps. The highly stable ceramide-enriched domains in DEC-Ceramide bilayers and the effect of different levels of cholesterol as well as of diblock copolymers, on the nanomechanical stability of the model systems studied were further examined. For the proteins of the barnacle adhesive, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and chemical staining with amyloid-selective dyes, in addition to AFM imaging, indentation, and pulling experiments were performed to study the structure and nanomechanics of the polymerized barnacle glue. Nanoscale structures exhibiting rod-shaped, globular, and irregularly shaped morphologies were observed in the bulk barnacle cement by AFM. SEM coupled with energy dispersive x-ray (EDX) makes evident the organic nature of the rod-shaped nanoscale structures while FTIR spectroscopy on the bulk cement gave signatures of β-sheet and random coil conformations. Indentation data yielded higher elastic moduli for the rod-shaped structures as compared to the other structures in the bulk cement. Single molecule AFM force-extension curves on the matrix of the bulk cement often exhibited a periodic sawtooth-like profile, observed in both extend and retract portions of the force curve. Rod-shaped structures stained with amyloid protein-selective dyes (Congo Red and Thioflavin-T) revealed that about 5% of the bulk cement are amyloids.