Origins and genetic conservation of tropical trees in agroforestry systems: a case study from the Peruvian Amazon

Abstract

Hundreds of native tree species are currently found in extensive agroforestry ecosystems in the Peruvian Amazon, forming an important reservoir of biodiversity. To further promote conservation, farmers are encouraged to supplement intra-specific genetic diversity in these populations with seed collected from local forests. For some tree species, however, this approach may be inappropriate, as stands of these taxa already found on-farm may not be of local origin. Despite this issue being of importance for conservation, little information is available on the history of cultivated trees in the region, a situation that we here rectify for the important fruit tree Inga edulis.Based on nuclear SSR and chloroplast DHPLC analyses of closely geographically matched natural and planted stands at five sites, it appears that cultivated material of I. edulis is primarily of non-local origin, indicating that conservation based on new wide-scale infusions from local wild stands into farms may be inappropriate in the region. Although nuclear and chloroplast diversity were both lower in planted stands, values were still relatively high (~80 and 70% of natural stands, respectively), indicating that when farmers plant trees, good collection practice of seed from already cultivated I. edulis should be an effective means for ensuring long-term conservation on farms.

Origin and Domestication of Native Amazonian Crops

“…Nuclear SSRs and chloroplast DNA were used to evaluate the origin of five pairs of planted and wild populations in the Peruvian Amazon, with the intention of determining whether these were derived from local wild populations [113]. The cultivated populations did not have local origin.…”

Assessment of the domestication state of ackee (Blighia sapida K.D. Koenig) in Benin based on AFLP and microsatellite markers

“…Farmers must be trained to maintain good collection practices of currently cultivated ackee germplasm as they regenerate the species in subsequent cycles of mating and selection of on-farm propagation (Dawson et al 2008). To extend domestication activities, exchange of germplasm should be limited to neighboring farms and villages.…”

“…Cross-species amplification of the Litchi chinensis primers used was previously reported in Euphoria longan and Nephelium rambutan-ake; all four species belong to the Sapindaceae family (Viruel and Hormaza 2004;Sim et al 2005). Chloroplast microsatellite markers are frequently used in phylogeographic analyses of plant species (Fontaine et al 2004;Muller et al 2009) but also to infer the origin of planted tree stands on-farm (Dawson et al 2008).…”

Managing genetic variation in tropical trees: linking knowledge with action in agroforestry ecosystems for improved conservation and enhanced livelihoods

“…However, molecular genetic variation in farmland stands was still 70-80% of that in forest, suggesting that planted populations could still be useful resources for conservation. Further analysis indicated that farmland populations of inga were diVerentiated from local wild material and were derived from multiple sources (Dawson et al 2008b), meaning that a strategy in which inga seed collected from natural forest is planted in neighbouring farmland may not be appropriate for conservation, due to the potential risks of outbreeding depression (dilution of locally adapted alleles and/or the breakdown of co-adapted gene complexes, Ledig 1992). In jocote, Schaal (2005, 2006) found that molecular variation in cultivated stands in…”