Population genetic and conservation of the native xerophytic species Balsamocarpon brevifolium from the Southern Atacama Desert, Chile

Abstract

Drylands comprise one third of the Earth´s land surface and occur all around the world representing the most extensive terrestrial biome (Thomas, 1997). They are one of the most vulnerable biomes due to their ecological complexity. The main characteristic of arid environment (deserts or drylands) is the low precipitation. Temperature conditions in deserts are extreme, reaching daytime temperatures up to 45°C and dropping drastically below to freezing point at the night. Deserts are classified by many features such as, amount of precipitation, geographical location, prevailing temperature, cause of desertification, among others; but the widely accepted system of desert classification is the one established by Meigs in 1953, dividing desert regions into three categories according to the amount of annual precipitation. Accordingly, there are extremely arid deserts that have at least 1 year without rainfall, arid lands having less than 250 mm of annual rainfall and semiarid regions having an annual precipitation between 250 mm and 500 mm. Deserts have the reputation to possess lack of life, but depending on which kind of desert, it can hold an impressive high biodiversity. Furthermore, this biome harbors some of the most endangered species in the world (UNCDD, 2011). Every living being that inhabits arid zones has evolved to withstand extreme conditions; for instance, plants are adapted to minimize water loss and to bear drastic temperature changes and animals like reptiles have adopted some behaviors that allow them to live in this hostile environment. The richness of flora and fauna in desert areas is important to the local livelihood. However, about the third of the world´s deserts have been converted by humans to economical land use; for instances in Southern Africa, large areas of dryland are being gradually desertified from overgrazing by livestock (MEA, 2005).