Evolutionary response of landraces to climate change in centers of crop diversity

Abstract

Landraces cultivated in centers of crop diversity result from past and contemporary patterns of natural and farmer-mediated evolutionary forces. Successful in situ conservation of crop genetic resources depends on continuity of these evolutionary processes. Climate change is projected to affect agricultural production, yet analyses of impacts on in situ conservation of crop genetic diversity and farmers who conserve it have been absent. How will crop landraces respond to alterations in climate? We review the roles that phenotypic plasticity, evolution, and gene flow might play in sustaining production, although we might expect erosion of genetic diversity if landrace populations or entire races lose productivity. For example, highland maize landraces in southern Mexico do not express the plasticity necessary to sustain productivity under climate change, but may evolve in response to altered conditions. The outcome for any given crop in a given region will depend on the distribution of genetic variation that affects fitness and patterns of climate change. Understanding patterns of neutral and adaptive diversity from the population to the landscape scale is essential to clarify how landraces conserved in situ will continue to evolve and how to minimize genetic erosion of this essential natural resource.

Assessing the vulnerability of traditional maize seed systems in Mexico to climate change

“…Highland Mexican races, which show introgression with teosinte (Zea mays subspecies mexicana) (23) and have a high genetic diversity among New World maize races (24), may be the most threatened because of their strong local adaptation. This strong local adaptation, coupled with shifts in climate (14), suggests that highland landraces are more vulnerable to climate change and merit special attention to assure conservation of genetic resources. Furthermore, ecological adaptation is not enough to guarantee successful adoption and adaptation by farmers: Germplasm also must have the necessary traits to make maize populations competitive for specific uses in these environments, such as consumption preferences and suitability for the niche markets for maize landraces that are important for farmers' livelihood security (25,26).…”

“…Furthermore, the country is the center of domestication and diversity for maize (9,10), and this diversity still is maintained and managed on-farm by many of these smallscale farmers (11)(12)(13). Traditional maize seed systems hence are important not only for farmers' livelihoods but also for the maintenance and evolution of Mexican maize landraces (14), one of the last reservoirs of maize genetic resources.…”

Wheat Landraces: A mini review <br>

“…The landraces and old cultivars they developed can be considered as evolutionary links between wild emmer wheat, the wild progenitor of all domesticated wheats, and advanced wheat cultivars. The extinction of traditional farming systems, erosion, or even the aging and exodus of rural population, and more recently, environmental degradation (Mercer and Peralis, 2010), have led to the extinction of many local landraces. As a consequence, during the last century most of the unique cereal biodiversity has disappeared and the information regarding landraces and traditional cultivars is presently very scarce.…”

Impactos del cambio climático en la distribución potencial de Morus alba L. en México

“…However, in the event that some populations of M. alba were near retraction areas of fitness in the coming years, it would have to consider that these populations will have only two options for survival: a) migrate to more favorable environments; or b) adapt to new weather conditions (Morueta-Holme et al, 2010), which largely depends on the genetic diversity of the species (Mercer and Perales, 2010). For the present study, the environmental fitness will lose a little more area due to climate change, and this, apparently, could promote further loss of M. alba spreading to new areas.…”