Domestication of Peach Palm in Southwestern Amazonia

The peach palm (Bactris gasipaes Kunth) is the only Neotropical palm domesticated by Native Americans. Its place of origin as a crop (B. gasipaes var. gasipaes) has been debated for more than a century, with three hypotheses currently in discussion: southwestern Amazonia; northwestern South America; or multiple origins in the distribution of the wild relatives (B. gasipaes var. chichagui). The small amount of archaeological data available supports the second hypothesis, but they contrast dramatically with the molecular-genetic analyses that support the first or the third, depending on how they are interpreted. On morphological grounds, two of the three types of var. chichagui are plausible candidates for wild ancestral populations. All the molecular-genetic analyses have identified a deep division between the landraces of cultivated peach palm in western Amazonia to Central America and those in southwestern to eastern Amazonia. The first analysis using isoenzymes linked the Tembe population (Bolivia) with the Pará landrace (eastern Amazonia), and these were distant from the western landraces. Multiple RAPD and SSR analyses identified the same deep division, which was interpreted by the group of researchers in Brazil as a single domestication in southwestern Amazonia with two dispersals, while another group working in Costa Rica interpreted it as three domestication events. Analysis with nuclear markers does not allow discrimination among the hypotheses, because gene flow may occur via pollen and seed. A new analysis with two sequences from the chloroplast genome, which has maternal inheritance and is therefore more appropriate to test the hypothesis, suggests that the cultivated peach palm was domesticated once in southwestern Amazonia, with two dispersals. One dispersal started in the upper Ucayali River basin, in southeastern Peru, and then throughout western Amazonia, northwestern South America and southern Central America. Another dispersal started in the upper Madeira River basin and then along the Madeira River into eastern Amazonia. New explorations in southwestern Amazonia are critical to identify the exact location of the original events

Origin and domestication of native Amazonian crops

Molecular analyses are providing new elements to decipher the origin, domestication and dispersal of native Amazonian crops in an expanding archaeological context. Solid molecular data are available for manioc (Manihot esculenta), cacao (Theobroma cacao), pineapple (Ananas comosus), peach palm (Bactris gasipaes) and guaraná (Paullinia cupana), while hot peppers (Capsicum spp.), inga (Inga edulis), Brazil nut (Bertholletia excelsa) and cupuassu (Theobroma grandiflorum) are being studied. Emergent patterns include the relationships among domestication, antiquity (terminal Pleistocene to early Holocene), origin in the periphery, ample pre-Columbian dispersal and clear phylogeographic population structure for manioc, pineapple, peach palm and, perhaps, Capsicum peppers. Cacao represents the special case of an Amazonian species possibly brought into domestication in Mesoamerica, but close scrutiny of molecular data suggests that it may also have some incipiently domesticated populations in Amazonia. Another pattern includes the relationships among species with incipiently domesticated populations or very recently domesticated populations, rapid pre- or post-conquest dispersal and lack of phylogeographic population structure, e.g., Brazil nut, cupuassu and guaraná. These patterns contrast the peripheral origin of most species with domesticated populations with the subsequent concentration of their genetic resources in the center of the basin, along the major white water rivers where high pre-conquest population densities developed. Additional molecular genetic analyses on these and other species will allow better examination of these processes and will enable us to relate them to other historical ecological patterns in Amazonia. © 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland

Crop domestication in the upper Madeira River basin

Most native Amazonian crops were domesticated in the periphery of the basin. The upper Madeira River basin is an important part of this periphery where several important crops were domesticated and others are suspected to have been domesticated or arrived early. Some of these crops have been reasonably well studied, such as manioc, peanut, peach palm, coca and tobacco, while others are not as well known, such as the hot peppers Capsicum baccatum and C. frutescens, and still others need confirmation, such as cocoyam and annatto. We review the information available for manioc, peach palm, Capsicum, peanut, annatto and cocoyam. The state-of-the-art for Capsicum frutescens, annatto and cocoyam is insufficient to conclude definitively that they were domesticated in the upper Madeira, while all the others have at least one of their origins or centers of diversity in the upper Madeira

Variabilidade genética e fluxo gênico em populações híbridas e silvestres de pupunha acessada com marcadores RAPD

As populações híbridas de pupunha (Bactris gasipaes Kunth) acumularam variabilidade genética provenientes de raças primitivas ao seu redor, o que deveria aumentar sua variabilidade. Para testar esta hipótese, avaliou-se a variabilidade genética de populações híbridas por meio de marcadores RAPD utilizando 176 plantas mantidas no Banco Ativo de Germoplasma do INPA, Manaus-AM, sendo quatro populações híbridas [Belém (n=26); Manaus (n=38); Iquitos, Peru (n=41); Yurimáguas, Peru (n=41)], duas populações silvestres (B. gasipaes variedade chichagui) tipos 1 (n=21) e 3 (n=7), e duas amostras de espécie afim, B. riparia, e compararam-se os parâmetros genéticos com estudos das raças primitivas. Oito iniciadores RAPD geraram 88 marcadores polimórficos e 11 monomórficos. O teste de replicabilidade apresentou uma similaridade de Dice 0,67, considerado aceitável. A heterozigosidade média das populações híbridas foi 0,34 e o polimorfismo foi 87,9%, maiores que nas silvestres (0,31; 74,7%). O dendrograma das similaridades de Dice não apresentou grupos que representassem claramente as populações híbridas. O fluxo gênico entre Iquitos e Yurimáguas (Nm=12,75) e entre Iquitos e Manaus (Nm=9,47) foi alto, enquanto o fluxo entre Belém e Manaus (Nm=7,72) foi menor que o esperado, possivelmente devido à influência da raça Solimões. O alto valor de heterozigosidade em Manaus (0,31) parece ser resultado da união de duas dispersões após a domesticação: a do oeste amazônico, com Iquitos e Yurimáguas, e a do leste amazônico, com Belém, que se juntam em Manaus. No entanto, essas populações não apresentaram acúmulo de variabilidade genética tão expressiva para diferenciá-las das raças primitivas

Origin and Dispersal of Domesticated Peach Palm

Peach palm (Bactris gasipaes Kunth) is a Neotropical palm domesticated by Native Americans. Its domestication resulted in a set of landraces (var. gasipaes), some with very starchy fruit used for fermentation, others with an equilibrium of starch and oil used as snacks. Which of the three wild types (var. chichagui) was involved and where the domestication process began are unclear, with three hypotheses under discussion: an origin in southwestern Amazonia; or in northwestern South America; or multiple origins. We reevaluate one of the wild types, defining it as the incipient domesticate, and then evaluate these hypotheses using the Brazilian peach palm Core Collection and selected herbaria samples to: (1) model the potential distributions of wild and domesticated populations; (2) identify the probable origin of domestication with a phylogeographic analysis of chloroplast DNA sequences; and (3) determine the dispersal routes after domestication using spatial analysis of genetic diversity based on 17 nuclear microsatellite loci. The two very small-fruited wild types have distinct distributions in the northern Andes region and across southern Amazonia, both under moderately humid climates, while the incipient domesticate, partly sympatric with the southern wild type, is also found along the Equatorial Andes, in a more humid climatic envelope, more similar to that of the domesticated landraces. Two distribution models for Last Glacial Maximum conditions (CCSM4, MIROC) also suggest distinct distributions for the two wild populations. The chloroplast DNA phylogeographic network confirms the area of sympatry of the incipient domesticate and the southern wild type in southwestern Amazonia as the origin of domestication. The spatial patterns of genetic diversity confirm the proposal of two dispersals, one along the Ucayali River, into western Amazonia, northwestern South America and finally Central America; the other along the Madeira River into central and then eastern Amazonia. The first dispersal resulted in very starchy fruit for fermentation, while the second may have been later and resulted in snack fruits. Further explorations of southwestern Amazonia are essential for more precise identification of the earliest events, both with new archeological methods and genetic analyses with larger samples