The Domestication of the Amazon Tree Grape (Pourouma cecropiifolia) Under an Ecological Lens

Abstract

Domestication studies traditionally focus on the differences in morphological characteristics between wild and domesticated populations that are under direct selection, the components of the domestication syndrome. Here, we consider that other aspects can be modified, because of the interdependence between plant characteristics and the forces of natural selection. We investigated the ongoing domestication of Pourouma cecropiifolia populations cultivated by the Ticuna people in Western Amazonia, using traditional and ecological approaches. We compared fruit characteristics between wild and domesticated populations to quantify the direct effects of domestication. To examine the characteristics that are not under direct selection and the correlated effects of human selection and natural selection, we investigated the differences in vegetative characteristics, changes in seed:fruit allometric relations and the relations of these characteristics with variation in environmental conditions summarized in a principal component analysis. Domestication generated great changes in fruit characteristics, as expected in fruit crops. The fruits of domesticated plants had 20× greater mass and twice as much edible pulp as wild fruits. The plant height:DBH ratio and wood density were, respectively, 42% and 22% smaller in domesticated populations, probably in response to greater luminosity and higher sand content of the cultivated landscapes. Seed:fruit allometry was modified by domestication: although domesticated plants have heavier seeds, the domesticated fruits have proportionally (46%) smaller seed mass compared to wild fruits. The high light availability and poor soils of cultivated landscapes may have contributed to seed mass reduction, while human selection promoted seed mass increase in correlation with fruit mass increase. These contrasting effects generated a proportionately smaller increase in seed mass in domesticated plants. In this study, it was not possible to clearly dissociate the environmental effects from the domestication effects in changes in morphological characteristics, because the environmental conditions were intensively modified by human management, showing that plant domestication is intrinsically related to landscape domestication. Our results suggest that evaluation of environmental conditions together with human selection on domesticated phenotypes provide a better understanding of the changes generated by domestication in plants.

Domestication Syndrome in Dacryodes edulis (Burseraceae): Comparison of Morphological and Biochemical Traits between Wild and Cultivated Populations

“…The increase in size of some organs such as reproductive structures in home gardens is in agreement with expectations for trees that would have been selected for their edible fruits and can be interpreted as a domestication syndrome resulting from the history of cultivation of the species and human selection [ 31 , 32 ]. One of the factors responsible for an increase of organ size in the cultivated compartment can be the lower level of environmental stress [ 11 ], which, in turn, would allow a greater resource allocation to flowering/fructification. Altogether, the relationship between female flower size (i.e., ovary size) and fruit size does not seem to be straightforward, and would require further investigation, particularly at the intraspecific level.…”

“…Both human and environmental factors generate selective pressures that affect the phenotypes of cultivated individuals, leading to morphological and genetic divergences from their wild ancestors [ 9 , 10 ]. Moreover, genetic variability in cultivated populations is generally reduced in comparison to wild populations due to the selection of a limited number of wild individuals with interesting traits for their introduction into cultivation, process better known as the domestication bottleneck [ 11 ]. On the other hand, cultivation generally results in an improvement of users’ preferred traits (e.g., fruit and seed size) in cultivated populations as compared to their wild ancestral populations [ 12 ].…”

Eighty-four per cent of all Amazonian arboreal plant individuals are useful to humans

“…This suggests that people do not try to manage these species in mature forests, such as the forests inventoried by the ATDN. Instead, fully domesticated species are adapted and kept in agroecosystems created and maintained by people [22,34,79]. A higher number of fully domesticated individuals in Amazonian landscapes is thus expected in homegardens and swiddens where they are still cultivated [33,34,36].…”

Fruit Quality Characters of Myrtle (Myrtus communis L.) Selections: Review of a Domestication Process

“…Plant domestication still remains as a tool to increase a multipurpose and sustainable agriculture, and many scientists work all over the world to study the available diversity of wild species with a clear orientation towards domestication [42]. The domesticated cultivars obtained by natural and human selection, as well as the environmental influences, lead to changes in morphological, phenotypic, and vegetative traits [43][44][45]. This review aimed to describe the work that has been done so far on myrtle domestication, as well as to evaluate the influence of the process on some fruit and leaf characters.…”