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 OPEN ACCESSDiversity 2010, 2 73 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.

Helicoverpa armigera is one of the primary agricultural pests in the Old World, whereas H. zea is predominant in the New World. However, H. armigera was first documented in Brazil in 2013. Therefore, the geographical distribution, range of hosts, invasion source, and dispersal routes for H. armigera are poorly understood or unknown in Brazil. In this study, we used a phylogeographic analysis of natural H. armigera and H. zea populations to (1) assess the occurrence of both species on different hosts; (2) infer the demographic parameters and genetic structure; (3) determine the potential invasion and dispersal routes for H. armigera within the Brazilian territory; and (4) infer the geographical origin of H. armigera. We analyzed partial sequence data from the cytochrome c oxidase subunit I (COI) gene. We determined that H. armigera individuals were most prevalent on dicotyledonous hosts and that H. zea were most prevalent on maize crops, based on the samples collected between May 2012 and April 2013. The populations of both species showed signs of demographic expansion, and no genetic structure. The high genetic diversity and wide distribution of H. armigera in mid-2012 are consistent with an invasion period prior to the first reports of this species in the literature and/or multiple invasion events within the Brazilian territory. It was not possible to infer the invasion and dispersal routes of H. armigera with this dataset. However, joint analyses using sequences from the Old World indicated the presence of Chinese, Indian, and European lineages within the Brazilian populations of H. armigera. These results suggest that sustainable management plans for the control of H. armigera will be challenging considering the high genetic diversity, polyphagous feeding habits, and great potential mobility of this pest on numerous hosts, which favor the adaptation of this insect to diverse environments and control strategies.

Shifting cultivation in the humid tropics is incredibly diverse, yet research tends to focus on one type: long-fallow shifting cultivation. While it is a typical adaptation to the highly-weathered nutrient-poor soils of the Amazonian terra firme, fertile environments in the region offer opportunities for agricultural intensification. We hypothesized that Amazonian people have developed divergent bitter manioc cultivation systems as adaptations to the properties of different soils. We compared bitter manioc cultivation in two nutrient-rich and two nutrient-poor soils, along the middle Madeira River in Central Amazonia. We interviewed 249 farmers in 6 localities, sampled their manioc fields, and carried out genetic analysis of bitter manioc landraces. While cultivation in the two richer soils at different localities was characterized by fast-maturing, low-starch manioc landraces, with shorter cropping periods and shorter fallows, the predominant manioc landraces in these soils were generally not genetically similar. Rather, predominant landraces in each of these two fertile soils have emerged from separate selective trajectories which produced landraces that converged for fast-maturing low-starch traits adapted to intensified swidden systems in fertile soils. This contrasts with the more extensive cultivation systems found in the two poorer soils at different localities, characterized by the prevalence of slow-maturing high-starch landraces, longer cropping periods and longer fallows, typical of previous studies. Farmers plant different assemblages of bitter manioc landraces in different soils and the most popular landraces were shown to exhibit significantly different yields when planted in different soils. Farmers have selected different sets of landraces with different perceived agronomic characteristics, along with different fallow lengths, as adaptations to the specific properties of each agroecological micro-environment. These findings open up new avenues for research and debate concerning the origins, evolution, history and contemporary cultivation of bitter manioc in Amazonia and beyond.

important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

Manioc is the most important food crop that originated in Amazonia. Many studies have increased our understanding of its evolutionary dynamics under cultivation. However, most of them focused on manioc cultivation in environments with low soil fertility, generally Oxisols. Recent ethnobotanical observations showed that bitter manioc also performs well in high fertility soils, such as Amazonian dark earths (ADE) and the floodplain. We used 10 microsatellite loci to investigate the genetic diversity and structure of bitter manioc varieties grown in different soil types in communities of smallholder farmers along the middle Madeira River in Central Amazonia. The genetic diversity of some sweet varieties and seedlings was also evaluated. Adult individuals showed higher levels of genetic diversity and smaller inbreeding coefficients (A ( R ) = 5.52, H ( O ) = 0.576, f = 0.086) than seedlings (A ( R ) = 4.39, H ( O ) = 0.421, f = 0.242). Bitter manioc varieties from the floodplain showed higher levels of genetic diversity (A ( R ) = 5.19, H ( O ) = 0.606) than those from ADE (A ( R ) = 4.45, H ( O ) = 0.538) and from Oxisols (A ( R ) = 4.15, H ( O ) = 0.559). The varieties grown in the floodplain were strongly differentiated from the varieties grown in Oxisols (F ( ST ) = 0.093) and ADE (F ( ST ) = 0.108), suggesting important genetic structuring among varieties grown in the floodplain and upland soils (ADE and Oxisols). This is the first time that genetic divergence of bitter manioc varieties in cultivation in different Amazonian soils in a small geographic area is reported.

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. Keywords: Amazonian crops. Center of domestication. Crop domestication. Southwestern AmazoniaResumo: A maioria dos cultivos nativos da Amazônia foi domesticada na periferia da bacia. A bacia do alto rio Madeira é uma parte importante dessa periferia, onde se suspeita que vários cultivos importantes foram domesticados, alguns são confirmados e outros possivelmente chegaram há muito tempo na região. Alguns destes cultivos foram razoavelmente bem estudados, tais como mandioca, amendoim, pupunha, coca e tabaco, enquanto outros não são tão bem conhecidos, como as pimentas Capsicum baccatum e C. frutescens, e ainda outros precisam de confirmação, como taioba e urucum. Revisamos as informações disponíveis para a mandioca, pupunha, Capsicum, amendoim, urucum e taioba. O estado da arte de Capsicum frutescens, urucum e taioba é insuficiente para concluir definitivamente que eles foram domesticados no alto rio Madeira, enquanto todos os outros têm pelo menos uma das suas origens ou centros de diversidade na região.

The genus Helicoverpa (Lepidoptera: Noctuidae) includes phytophagous and polyphagous agricultural insect pests. In the Americas, a native pest, Helicoverpa zea (Boddie), and an invasive pest, Helicoverpa armigera (Hübner), are causing severe damage in vegetable and agronomic crops. The population structure of both species in South America is poorly understood, and the phylogenetic relatedness of H. armigera and H. zea suggests natural interspecific gene flow between these species. Using microsatellite loci, we investigated: 1) the genetic diversity and gene flow of H. armigera specimens from Brazil; 2) the genetic diversity and gene flow between H. zea specimens from Brazil and the United States; and 3) the possibility of interspecific gene flow and the frequency of putative hybrids in Brazil. We detected high intraspecific gene flow among populations collected in the same country. However, there is a geographic limit to gene flow among H. zea individuals from South and North America. Pairwise Fst and private alleles showed that H. armigera is more similar to H. zea from Brazil than H. zea from the United States. A comparative STRUCTURE analysis suggests natural hybridization between H. armigera and H. zea in Brazil. High gene flow and natural hybridization are key traits to population adaptation in new and disturbed environments, which can influence the management of these pests in the American continent.

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