Reproductive biology of five native plant species from the Monte Desert of Argentina

Abstract

Research into plant breeding systems enables the evaluation of whether seed production depends on pollination agents and gene flow mechanisms within and among populations. This aids, in turn, the estimation of the appropriate population sizes needed to maintain both genetic and species' diversity. Little is known about plant reproductive biology in the Monte Desert (Patagonia, Argentina), a habitat threatened by desertification as a result of human impact. The mating systems, flowering phenologies and pollinator networks were studied in five representative plant species of the Monte Desert. The mating systems studied ranged from anemophilous pollen dispersion in the dioecious Atriplex lampa, to a gradient of dependence on pollinators, from the less dependent (facultative self-compatible) Gutierrezia solbrigii and two Larrea spp. (L. divaricata and L. cuneifolia) to the most dependent Grindelia chiloensis (self-incompatible). Flowering phenology was restricted to spring and coincided with pollinator abundance. Solitary bees were the main pollinator group, but beetles, flies and butterflies were also important. The four insect-pollinated species were moderately generalist, but they maintained their own pollinator assemblage. Coleopterans depended more on Grindelia chiloensis and dipterans on Gutierrezia solbrigii. Lepidopterans frequently visited Gutierrezia solbrigii and Larrea divaricata, whereas hymenopterans visited both Larrea spp. more frequently. The studied plant species are ecologically important, not only as resources for a wide range of pollinator species but also for other insects. The Monte Desert is a very disturbance-sensitive environment and, as these plant species hardly show vegetative regeneration, sexual reproduction is essential for their survival. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161, 190–201.