Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/16/2009
Publication Date: 12/16/2009
Citation: Jaradat, A.A. 2009. Dynamic Conservation of Date Palms: The Future of a Genetic Resource at the Nexus of Climate Change, Desertification and Salinity Stress in Oasis Ecosystems [abstract]. Proceedings of the QU Life Science Sympsoium, December 15-16, 2009, Doha, Qatar. 2009 CDROM.
Technical Abstract: The date palm (Phoenix dactylifera) is the only indigenous, wild desert plant definitely domesticated in its native harsh environment, and along with the camel (Camelus dromedarius), was responsible for opening the vast desert territories for human activity and the development of oasis ecosystems, which represent the climax of rigorous management of scarce water and land resources in alliance with the date palm. The date palm is composed of genetically discrete clones representing thousands of cultivars without the benefits of a dynamic mutation-recombination system, and is closely related to a variable aggregate of wild and feral palms distributed over a desert belt across West Asia and North Africa. Genetic diversity and genetic structure of the gene pool complex of date palm have been shaped and greatly altered by natural and human selection, clonal propagation, and by spatio-temporal exchange and movement of germplasm. A better understanding of the intra-specific genetic variation of date palm and its distribution in oasis ecosystems is essential for its conservation and sustainable use. Strategies for conservation and sustainable use, if properly designed and implemented, will (1) minimize anthropogenic disturbances, interference and impact; (2) optimize ecosystem functions; and (3) result in integrated protection of environmental resources. Climate change and anthropogenic factors play different, but equally important roles in oasis evolution on different temporal scales. The impact of climate change on oasis evolution is continuous and is manifested over large areas, whereas the impact of anthropogenic factors is local and disconnected. A complex of interacting components of climate change (higher temperature, low rainfall, greenhouse gas emissions, pollution, and biotic stresses), desertification (loss of organic matter, depletion of underground water, soil degradation and erosion), and salinity stress (toxic salts, loss of fresh water, intrusion of sea water, soil salinization, loss of biodiversity), in addition to consumer preferences and market forces, are impacting the diversity and varietal composition of date palm groves in the fragile oasis ecosystems. Sustainability and provision of multiple services of these ecosystems depend largely on a highly diverse genetic base of date palms. In-depth assessment of the genetic vulnerability of date palm to climate change, desertification and salinity stress requires knowledge of the extent and distribution of its genetic diversity, both of which depend on the species evolution and unique breeding system, past genetic bottlenecks, and ecological, geographical and anthropogenic factors. Knowledge of this diversity and its distribution, besides being important for its conservation and use, will help determine where, how, and what components of total genetic diversity to conserve. Date palm farmers practice de facto conservation and enhancement of genetic diversity by maintaining and manipulating traditional varieties and conscious selection of clones for various unique plant and fruit traits. However, the choice of which varieties or clones to grow is subject to each farmer's decisions, and the factors influencing farmer's choices are complex and not well understood. Therefore, an integrated system based on dynamic ex situ and in situ conservation of different components of date palm diversity, at the genetic, species, and ecosystem levels, offers the most rewarding form of conservation and serves the purpose of evolution, monitoring, management, and sustainable utilization of the species within the oasis ecosystem. In situ conservation of diversity in hotspots of key plant and fruit quality traits, and in remote oases, is better suited for rare and endangered biodiversity of flora and fauna of those ecosystems. Ex situ conservation of date palm is an alternative to in situ co