Animal farming and environmental interactions in the Mediterranean region

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, © Wageningen Academic Publishers 2012 , I. Casasús Animal farming and environmental interactions in the Mediterranean region EAAP publication No. 131, D 16 Animal farming and environmental interactions in the Mediterranean region will have to aim at mitigating the impact of the sector on climate change and environment, and at decreasing the competition with human food production, while maintaining fitness and productivity to remain viable. Together with husbandry practices and changes in species and breeds reared in geographic areas subjected to climatic fluctuations, molecular assisted breeding will play a key role in shaping existing livestock diversity to reach these challenging goals. Conservation genetics indicates that the ability of a species to evolve and rapidly adapt to new conditions is related to the genetic diversity it possesses. A highly uniform species may be very well adapted to its specific ecological niche, but unable to survive when conditions change (e.g. RossGillespie et al., 2007). The same is true at the population level. In accordance, in livestock both within and between population/breed diversity are key factors for ensuring the ability of a species to adapt to rapid change. However, the diversity in garm animal genetic resources (FAnGr) is rapidly decreasing, with a number of breeds becoming extinct or at risk at a very fast pace. During the last century, the European livestock sector has undergone striking changes as large-scale production expanded. The formulation of the modern breed concept during mid-1800s (Porter, 2007) and its application to breeding and husbandry practices led to the formation of well-defined breeds, exposed to intense anthropogenic selection. The progress of livestock management practices, the introduction of artificial insemination and embryo transfer, the improvements in feed technology and the use of vaccines and therapeutics against endemic diseases have fostered the diffusion of industrial breeding. This led farmers to progressively substitute the less productive, locally adapted, autochthonous breeds with highly productive cosmopolitan breeds and to progressively abandon agriculture in marginal areas (Taberlet et al., 2008). Therefore a significant number of cattle, sheep, and goat breeds already disappeared and many are presently endangered (FAO, 2007). The same process is now progressively taking place in Africa and Asia. According to the Food and Agriculture Organization of the United Nations (FAO, 2007), a total of 1,491 breeds worldwide (i.e. 20%) are classified as being either critically endangered, critical-maintained, endangered, or endangered-maintained. The highest number of breeds at risk is recorded in cattle (210 out of 1,311) followed by horses (181 out of 786). In sheep and goats the numbers of threatened breeds are 84 out of 618 and 179 out of 1,409 respectively. Cattle is also the species with the highest number of breeds reported as extinct (209), followed by sheep (180), pig (140), horse (87) and goats (19). The rate of extinction is also of great concern as it increased rapidly, from 1.21 breeds/year in the last century to 6.9 breeds/year in the last ten years (FAO, 2007). For historical, cultural and agro-ecological reasons, the Mediterranean region is extremely rich in livestock biodiversity, which should be conserved for a number of reasons, including their adaptation to specific environments. In this region 1,104 local, 110 regional and 420 international breeds are registered in the FAO Domestic Animal Diversity Information System (DAD-IS; Table 1)1. As in other regions of the world, local breeds, adapted to a variety of agro-climatic conditions and husbandry systems, are at the same time the most threatened, and the ones most lacking information on their risk status. One third of local Mediterranean breeds is at risk, while the risk status of another third is still unknown. Many breeds at risk suffer from low productivity, e.g. low milk yield in dairy cattle, but possess valuable characteristics as longevity (replacement rates between 11% and 25%) robustness and excellent adaptation to sometimes harsh local agro-ecologic and climatic conditions (Nardone, 1992). These characteristics are those most interesting for research and exploitation in a changing environment, and should not be lost. 1 Covers the whole territory of states including parts of the Mediterranean states located north of 45th parallel.