Genetic differentiation and trade among populations of peach palm (Bactris gasipaes Kunth) in the Peruvian Amazon—implications for genetic resource management

Abstract

Peach palm ( Bactris gasipaes Kunth) is cultivated for fruit and 'heart of palm', and is an important component of agroforestry systems in the Peruvian Amazon. In this study, AFLP was used to compare genetic diversity among domesticated populations along the Paranapura and Cuiparillo rivers, which are managed by indigenous and colonist farming communities, respectively. Gene diversity was 0.2629 for the populations in indigenous communities and 0.2534 in colonist communities. Genetic differentiation among populations ( G(st)) was 0.0377-0.0416 ( P<0.01) among populations along both rivers. There was no relation between genetic differentiation and the geographical location of populations along the rivers. Since natural seed dispersal by birds and rodents is thought to occur only across relatively short distances (100-200 m), it is likely that exchange of material by farmers and commercial traders is responsible for most of the 'long-distance' (over more than 20 km) gene flow among populations along the two rivers studied. This exchange of material may be important to counteract the effects of selection as well as genetic drift in small groups of trees in farmers' fields, much as in a metapopulation, and may account for the weak genetic differentiation between the two rivers ( G(st)=0.0249, P<0.01). A comparison with samples from other landraces in Peru and Brazil showed the existence of an isolation-by-distance structure up to 3,000 km, consistent with gene flow on a regional scale, likely mediated by trade in the Amazon Basin. Results are discussed with regard to practical implications for the management of genetic resources with farming communities.

Origin and Dispersal of Domesticated Peach Palm

“…They also confirm the commonness of both long and middle distance gene flow and introgression reported by various authors (Adin et al, 2004;Couvreur et al, 2006;Cole et al, 2007;Hernández-Ugalde et al, 2011). The fact that they do not fully validate the landrace hierarchy can be attributed to the design of the Core Collection (Cristo-Araújo et al, 2015), since this was not designed primarily to study the origin and dispersal of peach palm, but to support the management of peach palm germplasm at INPA.…”

“…Two accessions from the relatively spineless Guatuso populations of the Utilis landrace in Central America are assigned to the northern western Amazonia group, suggesting that spinelessness may not have been selected in situ but may be due to long distance dispersal, and the accessions from Coari, previously classified with the Putumayo landrace (Rodrigues et al, 2005), are assigned to the southern western Amazonia group, some 500 km to the west. Seed exchange networks had previously been identified within the Pampa Hermosa landrace in southern western Amazonia (Adin et al, 2004), as well as long distance gene flow between the southern and the northern western Amazonian groups (Cole et al, 2007), so this admixture is not surprising and may not be due to germplasm bank error.…”

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

“…Nevertheless, a small number of molecular studies on other indigenous trees in the Americas also indicate that use of non-local germplasm has contributed to the development of tree cultivation within the native range of a species. In particular, Bactris gasipaes, a palm tree with a long history of human use in the Amazon region and elsewhere in the Americas, appears to have undergone wide-scale dissemination through cultivation from one or a few primary sources rather than local domestication at many separate sites within the distribution of the wild progenitor Mora-Urpí et al 1997;Adin et al 2004;Rodrigues et al 2004). Recent work on traditional crops also indicates non-local sources in establishing cultivated populations within the native ranges of their progenitors within the Amazon region.…”

Low genetic diversity and recovery implications of the vulnerable Bankoualé Palm Livistona carinensis (Arecaceae), from North-eastern Africa and the Southern Arabian Peninsula

“…Conversely, Adin et al (2004) found that in the peach palm Bactris gasipaes bird dispersal was only local (100-200 m) and instead found that gene flow by human trading was likely to have lead to long distance dispersal and reduced genetic differentiation between populations from two adjacent rivers. Dowe et al (1997) found that many of the Carpoxylon macrospermum palm plants remaining on the Vanuatu islands had been cultivated by local villagers as they had some cultural significance.…”