congresos y reuniones científicas
Populations Genetic Tools Applied to Dryland Forest Restoration in Patagonia
Conferencia; Conferencia; Ecological Genetics Group Conference 2012; 2012; 2012
Institución organizadora:
Ecological Genetics Group
Understanding patterns of within-population diversity, inbreeding, and the degree of genetic divergence among populations can be of value to restoration projects if the goal is to promote the establishment of self-sustaining populations. Such a goal may include retaining local gene pools, maintaining sufficient adaptive genetic variation and ameliorating the deleterious effects of inbreeding in small or marginal populations. Drylands comprise 30% of the earth?s surface, and in South America, 94% of dry-temperate landscapes present some degree of environmental degradation, and lack of any kind of management. This reflects the widespread need for ecological restoration, that could potentially involve re-establishment of native forest cover. We analyzed geographic patterns of genetic variation in Austrocedrus chilensis, a dominant conifer of the steppe-forest ecotone in the eastern Andes, to examine its potential for restoration. Austrocedrus is of international conservation concern and IUCN listed it as Vulnerable, which means that is facing a high risk of extinction in the wild as a result in a decline in its distribution area. This species has been negatively affected by land use patterns, including logging, use of fire, and livestock grazing. Austrocedrus would be a candidate species for use in attempts to re-vegetate areas threatened by such anthropogenic processes, particularly under expected scenarios of climate change.We sampled 67 locations in Argentina and estimated genetic parameters to determine the effects of historical factors affecting diversity, together with inbreeding and gene-flow, using 12 allozyme loci. Genetic diversity decreased southwards in eastern populations, which are marginal for the range of the species and patchily distributed, while high genetic admixture was detected in continuous western populations, reflecting postglacial migrations from northern and eastern sources. Higher inbreeding (FIS> 0.14) was recorded in northern compared with southern populations, attributed to the impact of recent bottlenecks resulting from anthropogenic fires. Significant genetic structure was confirmed, average FST = 0.12, and admixture models showed that northern populations are most genetically distinct than southern ones. Implications of these results for restoration actions were: Relatively small, inbred yet genetically diverse northern populations should be the subject of passive restoration, while experimental common gardens should be established towards the south, to support active restoration approaches. So, at least two ?seed transfer zones? might be defined in Austrocedrus, within which plants can be moved with less consequences for population fitness. This illustrates how ahead of time information on patterns of genetic variation can support restoration efforts for dryland tree species.