Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs.

Fama y verdad en la épica quinientista española. El virgilianismo político y la tradición castellana del siglo xv

Fame and truth in Spanish XVth century epic. !e political vergilianism and the castilian tradition of the XVth century. The starting premise of this essay is that the Spanish Golden Age epic must be read from a historical perspective that takes into account the Hispanic literary tradition ofthe XVth century. In particular, it argues that epic should be approached from a theoretical perspective that explores its relationship with history in order to illuminate the diferences between Italian and Spanish epic theory and practice in the XVth century. The relationship between the discourses of epic and history can be explained through the imitation of the Vergilian model, specifically the Aeneid´s ideological representation of empire. However, it is also necessary to consider theoretical aspects in the light of the diferent uses of classical literature by Italian humanists and Castilian writers of the XV th century. Thus, its primary thesis is that although XVI th century Spanish epic shares the general principles of the Western Epic tradition, it should be approached from a specifically perspective Hispanic, in the light of the «political vergilianism» already enshrined in authors like Enrique de Villena and Juan de Mena, which is essential to appreciate how epic genre serves as memory for the present