SHORT COMMUNICATION: Do farmers reduce genetic diversity when they domesticate tropical trees? A case study from Amazonia

Abstract

Agroforestry ecosystems may be an important resource for conservation and sustainable use of tropical trees, but little is known of the genetic diversity they contain. Inga edulis, a widespread indigenous fruit tree in South America, is used as a model to assess the maintenance of genetic diversity in five planted vs. five natural stands in the Peruvian Amazon. Analysis of five SSR (simple sequence repeat) loci indicated lower allelic variation in planted stands [mean corrected allelic richness 31.3 (planted) and 39.3 (natural), P = 0.009]. Concerns regarding genetic erosion in planted Amazonian tree stands appear valid, although allelic variation on-farm is still relatively high.

Origin and Domestication of Native Amazonian Crops

“…The cultivated populations did not have local origin. Nuclear and chloroplast diversity were lower in the planted populations, ~80% and ~70% of the natural populations, respectively, similar to the earlier study [111].…”

“…Hollingsworth et al [111] used five SSR loci to evaluate the maintenance of the genetic diversity in five planted and five natural populations in the Peruvian Amazon. They found less variation in the planted populations compared with the natural [mean corrected allelic richness of 31.3 (planted) and 39.3 (natural), p = 0,009], exactly what is expected in domesticated plant populations [112].…”

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

“…Our estimates are close to values for agroforestry fruits species undergoing domestication processes with a continental distribution such as V. paradoxa (from Mali, West Africa; Sanou et al 2005) and Inga edulis (from Peruvian Amazon; Hollingsworth et al 2005) ( Table 6). The mean within-population diversity (H E = 0.286) is also lower than SSR mean values reported for long-lived perennial (H E = 0.68, n = 59), widespread (H E = 0.62, n = 31), outcrossing (H E = 0.65, n = 71) and late successional species (H E = 0.70, n = 34; Nybom 2004).…”

“…AFLP (Vos et al 1995) markers cover the whole genome, and have proven to be useful in assessing genetic variation and taxonomic relatedness in a large variety of wild and cultivated plant species (Miller and Schaal 2006;Emshwiller et al 2009). Nuclear microsatellites (nSSRs) are expected to be particularity effective to test for genetic bottlenecks associated with domestication (Kelly et al 2004;Hollingsworth et al 2005). 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).…”

Peach palm (Bactris gasipaes) in tropical Latin America: implications for biodiversity conservation, natural resource management and human nutrition

“…Optimization analysis, as proposed by Weitzman (1998), could help determine which populations can best be conserved in situ, considering the genetic distinctiveness of each population compared to others and the costs of implementing conservation measures that guard effectively against human pressures and progressive climate change. On-farm conservation could be an appropriate alternative for in situ conservation of wild populations, particularly if high levels of diversity are maintained in nearby cultivated populations and these are genetically close to wild populations (Hollingsworth et al 2005). Indeed, in many regions cultivated peach palm populations are closely related to nearby wild populations (Couvreur et al 2006;Hérnandez-Ugalde et al 2008 and they could complement in situ conservation of the wild populations that are genetically most distinct and most at risk of extinction.…”