Importance of the chemical defenses and sugars in the feeding preference of Paracentrotus lividus over two sympatric template seagrass species

Herbivory is a fundamental process regulating the functioning of the ecosystems both in land and marine systems. Few decades ago, herbivory was thought to play only a minor role in seagrass dominated areas, while currently its importance has risen. However, the complex interrelationships between seagrasses and their consumers are not yet fully understood. For instance, seagrasses can tune up morphological, biomechanical, nutritional, and chemical traits in order to reduce the palatability of their leaves and therefore curtail tissue losses, but the final tradeoff of such changes may depend on herbivore guilds. This work focuses on the relative importance of nutritional versus chemical traits in the feeding behavior of the sea urchin Paracentrotus lividus, a temperate generalist mesograzer, over two sympatric seagrass species (Cymodocea nodosa and Zostera noltei). To do that, a set of no-choice and multiple-choice feeding assays were conducted using freeze-dried plants agarbased diets (i.e. whole nutritional properties), polar extracts of both species (i.e. soluble sugars and phenolic natural products), purified phenolic natural products, and also three different concentrations of soluble sugars. Later, a chemical identification and quantification of the phenolic natural products present in the extracts were performed to assess their ecological role as deterrents. Results clearly indicated that the feeding behavior of this generalist herbivore, once overlooked the structural, morphological and biomechanical traits, is mainly determined by nutritional properties, while the presence of phenolic compounds has only a minimal effect on its feeding behavior. In addition, although this study showed that sugars had a positive effect over P. lividus consumption rates, we demonstrated for the first time the deterrent properties of rosmarinic acid and the sulphated flavonoids produced by Z. noltei, which were able to reduce the attractive effect of sugars in the feeding preference of this generalist herbivore

Photius at Work: Evidence from the Text of the <i>Bibliotheca</i>

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The Blessing of Necessity and Advantages of Newness

This chapter explores the advantages of newness and positive aspects of resource constraints, critically departing from assumptions of resource constraints and liabilities of newness. The chapter is based on a multiple case study consisting of nascent entrepreneurial processes from inexperienced entrepreneurs with severely constrained access to resources. Six theoretical concepts (legitimacy, fashion, flexibility, networks, bootstrapping, and motivation) are developed in the frame of reference. Empirical data is collected on a rich variety of sources, including longitudinal data in the form of weekly logbooks, business plans, theoretical reflections, and additional collected data during the process. Based on this data, the analysis shows that while these entrepreneurs face resource constraints and liabilities of newness, they also use strategies to leverage their constraints and novelty as an advantage in advancing their venturing efforts