F. Forzale

Occurrence and antimicrobial susceptibility of aeromonads from maricultured gilthead seabream (Sparus aurata)

The understanding of the genetic mechanisms of livestock adaptation to environmental challenges is becoming an important research topic in this time of rapid climate change. New tools and approaches are now available to investigate this complex phenomenon. Low-cost high-throughput technologies have opened the genomic era to agricultural species. All major farm animals have been completely sequenced and HapMap projects are completed or in progress. Low, medium and high-density SNP panels are available or under construction. Molecular information on many thousand markers has initiated the era of population genomics, which is the application of genomic approaches to population genetics. The comparison of patterns of diversity along the genome in animals originating in different environments and new GIScience-based models able to associate molecular markers to environmental variables promise to discover genomic regions associated to traits important for adaptation and to pave the way to the identification of causative genes. Local breeds adapted to a sustainable production in extreme and harsh environments will play a fundamental role in this process. Domestication, adaptation and biodiversity Response mechanisms to environmental challenges have been evolving in livestock populations for millions of years, first in wild ancestor species and, since the Neolithic, in derived domesticates. The post-domestication colonization of the world, along with agriculture expansion and human migrations, have often taken livestock species well outside the agro-climatic range of adaptation of wild ancestors, so that nowadays livestock species count thousand local populations adapted to environments as different as sub-Saharan Africa and Yacutia. Adaptation to local agro-climatic conditions and husbandry systems, and human selection towards different use and morphology, have maintained and shaped the original diversity, sometimes increasing it by promptly capturing useful mutations that would have most probably been lost by genetic drift or reduced fitness (e.g. myostatin mutations causing double muscling in beef cattle). This diversity is a treasure to humankind and guarantees a genetic pool wide enough to direct breeding towards new selection objectives when necessary. In the medium term perspective, one of these objectives is to improve adaptation to higher temperatures, drought and diseases. Projections, in fact, indicate a rapid trend towards a warmer planet and shorter plant growing periods in a large part of the planet. The tropics and subtropics will be affected the most. In these regions, by the end of this century growing season temperatures are expected to exceed the most extreme seasonal temperatures recorded from 1900 to 2006 (Battisti and Naylor, 2009). The consequences of climate change on food security and agriculture socio-economy are difficult to predict and will vary considerably from site to site, however consensus is that the risk of a negative effect in these areas is high (Müller et al., 2011). Europe will be affected, as well: reduced water supplies and increased production vulnerability are expected in the South, while mainly positive effects are predicted in the North (Falloon and Betts, 2010). In any case, in a large part of the world, agriculture will have to change dramatically to adapt to new conditions. Variations may firstly occur in crop production, in terms of both species and yield. Livestock production systems will have to adapt to these changes and to a number of direct (heat, drought) and indirect (new diet, new disease pressure) effects of climate change. At the same time, breeding and husbandry practices et al. (eds.), OI 10.3920/978-90-8686-741-7_1,