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In Situ, Ex Situ and On Farm Conservation of Plant Genetic Resources in Neotropics
Abstract
The prospect for the coming decades will be for humanity to witness a holocaust of species on Earth. Within these species are plants for food purposes undergoing genetic erosion and, putting at risk not only their own existence, but the safety of human life. Several genetic tools have been used in recent years to support breeding and conservation programs. Diverse agendas, from countless countries, endeavored to drive ex situ, in situ conservation, and the sustainable use of genetic resources for food and agriculture. Brazil, an example of country with a rich agrobiodiversity in Neotropics, has advanced in research and appreciation of plant genetic resources, however at the same time it has led vast biological losses. In this chapter, we will review some concepts related to plant genetic resources, present case studies for in situ, ex situ and on farm conservation and discuss some recommendations to safeguard the valuable genetic inheritance of food plants.KeywordsConservation strategiesPlant conservationGenetic diversityAgriculturalBiodiversity
The Amazonian native tree species Parkia multijuga has potential silvicultural characteristics that can be utilized to productive plantations. Understanding its mating system is necessary to delineate the methods for the breeding of the species, the collection of seeds for conservation, and the use of seedlings for production plantations. The aim of this study is to evaluate the mating system and population genetic diversity of P. multijuga, using molecular markers. The DNA of 221 plants was extracted and genotyped with nine microsatellite loci using capillary electrophoresis in an automated DNA sequencer. The estimates for single and multilocus crossing rates were 0.998 and 1.0, respectively. The paternity correlation was low (r^p(m) = 0.307). The fixation index (f) showed values below zero, indicating an excess of heterozygotes. The cluster number K = 2 shows a better grouping among families for genetic structure. P. multijuga families consist mainly of half-sibs, and the reproductive strategy of the species is allogamy.
In the Anthropocene, the world's plant diversity is threatened with extinction and the erosion of the genetic diversity of natural populations. According to the State of the World's Plants and Fungi 2020 of the Royal Botanic Gardens, Kew, two out of five of the ~350,000 known vascular plant species are at risk of extinction. Despite the considerable toolkit of biodiversity conservation practices, usually it is hard to choose the best option to stop biodiversity loss. Ex situ conservation has seen massive development due to radical losses of natural ecosystems, and its incrementing necessity has been underscored by Target 8 of the 2011-2020 Global Strategy for Plant Conservation. As we crossed the finish line of this strategy in 2020, a review of the accumulated knowledge on the ex situ living collections has become particularly important. Despite the increasing attention received by ex situ conservation, studies on the sustainability, quality, and usability of the plant material prior to establishing the garden collections are few, leaving major gaps unfilled in terms of best ex situ conservation practices. Here we present an overview of the results and experiences in ex situ conservation focusing on living plant collections, with the aim of guiding conservation practitioners towards the most efficient working methods. We evaluate the future needs and perspectives of this conservation technique, based on case studies on both woody and herb species. Possible conservation applications and priorities suggested for future works are summarized.
Introduction:
Spondias tuberosa is a tree endemic to the semiarid region of Brazil with fruticulture potential.
Objective:
To estimate the diversity and genetic structure of S. tuberosa accessions from four areas of the semiarid region of Brazil, in order to facilitate conservation genetic resources studies in this species.
Methods:
DNA was extracted, using the CTAB 2x method, from leaf samples of 24 accessions of S. tuberosa available in the germplasm bank at Embrapa Semiárido, Brazil. Ten microsatellite loci were used in this study.
Results:
The UPGMA dendrogram, generated with a Jaccard coefficient similarity matrix, contains four groups at a 0.44 cutoff point. The similarity coefficient ranged from 0.30 to 0.84, indicating great divergence among the accessions. A Bayesian analysis conducted with the software Structure suggests there are two subpopulations, one formed by accessions from the Januária region and another by accessions from the Juazeiro, Uauá and Petrolina regions. The ΦST value of 0.12 for the analysis of molecular variance indicates moderate genetic differentiation among the four populations, suggesting that the genetic variability is moderately structured in function of region.
Conclusions:
Together, the analyses indicate that the genetic diversity of S. tuberosa is not uniformly distributed in the studied regions. Thus, germplasm from a greater number of populations should be collected to increase the germplasm bank genetic diversity of the species.
Hancornia speciosa Gomes is native tree to South America, and its fruits are a source of income for communities and the food industry. The reduction of natural occurrence areas of H. speciosa, the absence of a sustainable management plan conservation and breeding programs, threaten its natural populations. Therefore, the purpose of this study was to evaluate the phenotypic variability of fruits, seeds, and seedlings and to estimate the genetic diversity. The main goal is to provide information for the conservation and breeding programs of the species. Measurable variables of fruits, seeds, and seedling; and genetic diversity was estimated by ISSR markers. Among fruits, 53.21% had a longitudinal diameter from 27.5 to 35 mm and 63.15% had a transversal diameter from 24.5 to 35 mm. The average seed biometry was 9.98 mm, 8.21 mm, and 3.97 mm, for length, width and thickness respectively. The length of seedlings shoots varied from 3.0 to 8.5 cm, roots from 4.0 to 15.8 cm and dry mass from 80 to 103 mg seedling−1. The genetic parameters estimated were He = 0.40, I = 0.50, Na = 2.0, Ne = 1.71 and similarity of 55.29%. The population has high phenotypic variability of fruits, seeds and seedlings, and genetic diversity. There is potential for use of this population in the enrichment process for the restoration of natural populations.
Cassava is one of the most important subsistence crops in tropical regions. It is necessary to preserve and to know the genetic diversity existent for the adequate use of genetic resources. The evaluation of genetic diversity among genotypes results in information about potential parents in breeding programs, allows duplicates identification, and facilitates germplasm exchange between research institutions. The objective of this study was to characterize the genetic diversity of cassava accessions of North Brazil region. A total of 106 accessions were analyzed using ten microsatellite markers. The genetic parameters estimated were: expected heterozygosity (HE), observed heterozygosity (HO) and polymorphic information content (PIC). Clustering was performed using the UPGMA and Neighbor-Joining (NJ) method. Bayesian analysis, analysis of principal coordinates and identification of a core collection were also used. The ten loci amplified 8,40 alleles on average. The average heterozygosity estimates were: HE = 0.71, HO = 0.58 and PIC = 0.72. Genetic distances ranged from 0.158 to 0.908. Six (5,66%) accesses were redundant. Clustering and dispersion analysis didn’t differentiate bitter from sweet cassava, and there wasn’t correlation between groups and collect origin. The core collection consisted of 22 individuals that represented 94% of total allelic diversity and 20,75% of the base collection. The results indicate high dissimilarity between the accessions and allowed the detection of redundant genotypes, showing the use of genetic markers as informative tools for the management of collections.
Several recent national and international projects have focused on large-scale genotyping of plant genetic resources in vegetatively propagated crops like fruit and berries, potatoes and woody ornamentals. The primary goal is usually to identify true-to-type plant material, detect possible synonyms, and investigate genetic diversity and relatedness among accessions. A secondary goal may be to create sustainable databases that can be utilized in research and breeding for several years ahead. Commonly applied DNA markers (like microsatellite DNA and SNPs) and next-generation sequencing each have their pros and cons for these purposes. Methods for large-scale phenotyping have lagged behind, which is unfortunate since many commercially important traits (yield, growth habit, storability, and disease resistance) are difficult to score. Nevertheless, the analysis of gene action and development of robust DNA markers depends on environmentally controlled screening of very large sets of plant material. Although more time-consuming, co-operative projects with broad-scale data collection are likely to produce more reliable results. In this review, we will describe some of the approaches taken in genotyping and/or phenotyping projects concerning a wide variety of vegetatively propagated crops.
Food production has seen various advancements globally in developing countries, such as India. One such advancement was the green revolution. Notably, the World Bank applauds the introduction of the green revolution as it reduced the rural poverty in India for a certain time. Despite the success of the green revolution, the World Bank reported that health outcomes have not been improved. During the post-green revolution period, several notable negative impacts arose. Exclusive studies were not conducted on the benefits and harms before the introduction of the green revolution. Some of such interventions deviate from the natural laws of balance and functioning and are unsustainable practices. To avoid the adverse effects of some of these developments, a review of these interventions is necessary.
Crop wild relatives (CWR) are important sources of adaptive diversity for plant breeding programmes. This paper aims to investigate the extent to which the centres of crop origin/diversity are congruent with areas of high CWR diversity. We established the predicted potential CWR distributions for 1,425 CWR species related to 167 crops using 334,527 known distribution locations and generated a global CWR hotspot map. This was then compared to the centres of origin/diversity proposed by Vavilov (amended by Hawkes); Zeven and Zhukovsky’s mega gene centres, Harlan’s centres and non-centres of crop domestication; and crop domestication areas identified using current archaeological evidence proposed by Purugganan and Fuller. Greatest congruence between the global CWR hotspots and other concepts was found with the concept proposed by Vavilov and amended by Hawkes, but there remained significant differences between the CWR hotspots and Vavilov’s concept. This paper concludes that all four centre concepts reviewed have some overlap with CWR diversity but that Vavilov’s original concept has the closest geographic coincidence with CWR hotspots. With the benefit of significant additional global datasets to those used by Vavilov, we were able to suggest amendments to his concept, adding further centres based on CWR hotspots in west and east USA, West Africa, South-east Brazil and Australia. As a result of this study more precise targeting of CWR and crop landrace can be implemented in future, aiding global food and nutritional security.
The Neolithic Revolution narrative associates early-mid Holocene domestications with the development of agriculture that fueled the rise of late Holocene civilizations. This narrative continues to be influential, even though it has been deconstructed by archaeologists and geneticists in its homeland. To further disentangle domestication from reliance on food production systems, such as agriculture, we revisit definitions of domestication and food production systems, review the late Pleistocene-early Holocene archaeobotanical record, and quantify the use, management and domestication of Neotropical plants to provide insights about the past. Neotropical plant domestication relies on common human behaviors (selection, accumulation and caring) within Citation: Clement, C.R.; Casas, A.; Parra-Rondinel, F.A.; Levis, C.; Peroni, N.; Hanazaki, N.; Cortés-Zárraga, L.; Rangel-Landa, S.; Alves, R.P.; Ferreira, M.J.; et al. Disentangling Domestication from Food Production Systems in the Neotropics. Quaternary 2021, 4, 4.
The Brazil nut is a highly valuable non-timber forest product from a wild, hyper-dominant, emergent tree species that is increasingly vulnerable and exposed to habitat degradation. We provide evidence for how Brazil nut genetic resources are negatively affected by forest degradation and discuss the consequences of this for reproductive success. To avoid negative effects of genetic erosion and inbreeding, we discuss the need to cease large-scale forest conversion and to promote landscape connectivity. This could support gene flow, maintain genetic diversity across individuals reproducing in clustered patterns and contribute to securing the long-termed reproductive viability and resilience of this high socioeconomically and ecologically valuable species.
Summary
• Ecosystem degradation in the Amazon drives this biodiverse rainforest toward an ecological tipping point. Sustainable management and restoration of degraded rainforest therein are central to counteract this crisis. One hyper-dominant, key-stone species of high ecological and socioeconomic value, the Brazil nut tree, offers additional benefits as a major carbon sink and a nutritional source of the most prominent globally traded non-timber forest product.
• Despite Brazil nut trees being protected by conservation regulation, forest degradation threatens sufficient gene-flow among Brazil nut tree populations. This has impacts on the reproductive success, genetic diversity, and consequently on the resilience of this species to environmental change.
• We used 13 microsatellite loci to explore the consequences of forest degradation on the reduction in genetic diversity of Brazil nut populations. We examined the clustering of genetically related individuals as fine-scale genetic structure (FSGS) and the variation in genetic diversity and inbreeding across adult trees and seedlings along a categorized forest-degradation gradient ranging from conserved to
Maize (Zea mays spp. mays L.) is the major domesticated cereal of the Americas and is of great relevance for global food security. For a long time, Amazonia represented an empty space in the racial distribution maps of this species, due to the lack of collections and the idea that locally developed races became extinct during European colonization. However , a native race had been described in Brazilian Amazonia, the Entrelaçado race, and a new study placed Amazonia on the map again, with a proposal for a center of diversification in Southwestern Ama-zonia. We prospected maize in the Brazilian states of Acre and Rondônia (Southwestern Brazilian Amazo-nia) and found floury landraces belonging to the Entrelaçado race, rare in existing collections and often considered extinct in the field. We collected indigenous and local names, general and specific uses for Entrelaçado, and characterized these accessions to compare them with other Brazilian floury maize races, based on data from the literature. Floury maize from the Southwest formed a coherent group in the cluster analysis, which grouped with Entrelaçado from the literature, confirming its identification and Electronic supplementary material The online version of this article (https://doi.().,-volV) (01234567 89().,-volV) demonstrating that this race is conserved in Southwestern Amazonia.
The present study aimed to assess population structure and phylogenetic relationships of nine subspecies of Brassica rapa L. represented with thirty-five accessions cover a wide range of species distribution area using isozyme analysis in order to select more diverse accessions as supplementary resources that can be utilized for improvement of B. napus. Enzyme analysis resulted in detecting 14 putative polymorphic loci with 27 alleles. Mean allele frequency 0.04 (rare alleles) was observed in Cat4A and Cat4B in sub species Oleifera accession CR 2204/79 and in subspecies trilocularis accessions CR 2215/88 and CR 2244/88. The highest genetic diversity measures were observed in subspecies dichotoma, accession CR 1585/96 (the highest average of observed (H0) and expected heterozygosity (He), and number of alleles per locus (Ae)). These observations make this accession valuable genetic resource to be included in breeding programs for the improvement of oilseed B. napus. The average fixation index (F) is significantly higher than zero for the analysis accessions indicating a significant deficiency of heteozygosity. The divergence among subspecies indicated very great genetic differentiation (FST = 0.8972) which means that about 90% of genetic diversity is distributed among subspecies, while 10% of the diversity is distributed within subspecies. This coincides with low value of gene flow (Nm = 0.0287). B. rapa ssp. oleifera (turnip rape) and B. rapa ssp. trilocularis (sarson) were grouped under one cluster which coincides with the morphological classification.
Ex situ conservation is widely used to protect wild plant species from extinction. However, it remains unclear how genetic variation of ex situ plant collections reflects diversity of wild source populations. We conducted a global meta‐analysis of the genetic representativeness of ex situ populations by comparing genetic diversity (i.e., AR, allelic richness; He, expected heterozygosity; PPB, percent polymorphic bands; and SWI, Shannon–Winner index), inbreeding coefficient (FIS), and genetic differentiation between ex situ plant collections and their wild source populations. Genetic diversity (i.e., He, PPB, and SWI) was significantly lower in ex situ populations than their wild source populations, whereas genetic differentiation between ex situ and wild populations (ex‐situ‐wild FST), but not that among ex situ populations, was significantly higher than among wild populations. Outcrossing species, but not those with mixed mating system, had significantly lower genetic diversity in ex situ populations and significantly higher ex‐situ‐wild FST. When the collection size for ex situ conservation was ≥30 or 50, PPB, He, and ex‐situ‐wild FST were not significantly different between ex situ and wild populations, indicating a relatively high genetic representativeness. Collecting from the entire natural distribution range and mixing collections from different sources could significantly increase the genetic representativeness of ex situ populations. Type of ex situ conservation (i.e., planting or seed bank) had no effect on genetic representativeness. The effect size of He decreased and the effect size of ex‐situ‐wild FST increased as the duration of ex situ conservation increased. Our results suggest that current ex situ plant collections do not effectively capture the genetic variation of wild populations. Low genetic representativeness of ex situ populations was caused by both initial incomplete sampling from wild populations and genetic erosion during ex situ conservation. We emphasize that it is necessary to employ more thorough sampling strategies in future collecting efforts and to add new individuals where needed.
The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.
The comparison of inter-population quantitative variation and neutral variation based on molecular markers (QST − FST) has been extensively used to infer the influence of different selection forces on potentially adaptive traits. Only recently have studies focused on two levels of inter-population genetic structuring: among regions (or groups) and among subpopulations within groups. This work aimed to compare quantitative and molecular variation within these two hierarchical levels for Hancornia speciosa Gomes, a fruit tree species that is native to the Brazilian Cerrado. Six quantitative traits related to initial plant growth were evaluated in a common garden environment using samples from 57 maternal families (treatments) derived from 29 subpopulations within four botanical varieties. The quantitative divergence among the botanical varieties (QGT) and among the subpopulations within varieties (QSG) for each trait were compared with the corresponding neutral variation (FGT and FSG) obtained based on six microsatellite loci using a parametric bootstrap procedure. The molecular results revealed a low degree of divergence among the botanical varieties and significant structuring among the subpopulations within varieties. The estimates of the quantitative divergence among the varieties (QGT) tended to be greater than the divergence among the subpopulations within varieties (QSG) for five out of the six quantitative traits. The comparison between the quantitative and molecular parameters suggests that divergent selection shaped the genetic structure among the botanical varieties for some traits, while the variation among the subpopulations within varieties was influenced by genetic drift and uniform selection.
The Historia Naturalis Brasiliae (HNB, 1648) is the most complete treatise on Brazilian flora and fauna created in the seventeenth century. Scientists Marcgrave and Piso depicted hundreds of plants and described uses, vernacular names, and diseases in Dutch Brazil. We aimed to verify whether these plants are still used similarly, using herbarium vouchers and taxonomic literature to identify the species described in the HNB and reviewing historical and modern ethnobotanical literature to analyze whether the HNB documented specific plants and uses for the northeast region. We highlighted Old World species, as they indicate plant introduction before and during the trans-Atlantic slave trade and exchange of African ethnobotanical knowledge. Of the 378 species found in the HNB, 256 (68%) were useful, mostly used for healing and food in a similar way (80%) both in the seventeenth century and in modern Brazil. Only one species (Swartzia pickelii) is endemic to northeast Brazil, while the others are more widely distributed. The HNB includes one of the first reports on African crops in Brazil, such as sesame, okra, and spider plant. This study brings insights on indigenous and African plant knowledge retentions since the creation of the HNB and acknowledges its non-European contributors.
The mangaba, Hancornia speciosa, (Apocynaceae) is a fruit tree native to Brazil with predominantly extractivist production. The fruit can be consumed in natura; however, it is widely consumed as frozen pulp and ice cream produced by agroindustry companies. We evaluated the genetic diversity of 213 individuals that make up the mangaba GeneBank of Embrapa Tabuleiros Costeiros, using nine microsatellite markers (SSR). A total of 147 alleles were identified, with a mean of 16 alleles per locus; 100% polymorphism was observed among accessions. Reliability of the result was verified based on stress (0.042) and correlation (0.988) values. The alleles presented a high frequency of heterozygosity (He > Ho). The Fst (0.22) and f (0.07) values indicated moderate population structure, with great diversity within accessions. Bayesian analysis indicated the most adequate grouping with k = 2. The Unweighted Pair Group Method analysis showed three distinct groups according to similarity. The BI accession had the best genetic structure. The PM5/GX2, CN1/CN9, G18/PA1, JA14/JA15, and OI8/OI9 pairs of individuals are the closest genetically. We conclude that the Mangaba GeneBank has high diversity; this knowledge is relevant to develop strategies for the management of these genetic resources.
Dipteryx alata is a Neotropical tree widely distributed throughout the Brazilian Cerrado biome and is popularly known as baru. In this study, we evaluated the mating system of D. alata and compared pollen dispersal patterns between the in situ and ex situ conditions. For this, we used 515 genotypes of adults, juveniles, and progeny from a natural population (in situ) in Orizona-GO, Brazil. In addition, we used 488 genotypes of adults and progeny from a germplasm collection (ex situ) located at the Federal University of Goiás. Both locations are situated in central Brazil. The genetic diversity, cross-pollination rates, and pollen dispersal distance under both conditions were estimated. Genetic diversity and polymorphism differed between the in situ and ex situ conditions. The average number of alleles found in situ (5.2) and ex situ (6.2) showed that the germplasm collection stores greater genetic diversity than the in situ condition. Cross-pollination detected among mother trees under both the in situ and ex situ conditions were high (tm = 0.815 and tm = 0.934, respectively), indicating that the species has a mixed reproductive system that was predominantly allogamous. The difference between tm and ts indicated that the in situ condition shows greater biparental inbreeding. Our results showed that, across generations, the ex situ condition preserved a larger number of alleles, confirming that the D. alata germplasm collection plays a role in conserving genetic diversity. The presence of self-fertilization suggests self-compatibility. Paternity correlation and the dispersal distance of the pollen donors were higher in the in situ condition, a maximum distance of 2.9 km of pollen flow. This can be explained by the number of pollinators and tree spatial distribution.
Global strategies under the scope of CBD are important in guiding policies and resources for the conservation of biological diversity. This paper emphasized the need to develop actions under the Global Strategy for Plant Conservation (GSPC) with measurable results up to 2020, regarding the status and perspectives related to Targets 12 and 13, focusing on the Brazilian context in order to identify gaps and actions to achieve the goals for conservation and sustainable use of plants. It should be noted that Target 12 also covers logging, not necessarily directly related to indigenous peoples and traditional communities, but may threaten their livelihoods. In Brazil, scientific knowledge about the ecological effects of the harvesting of non-timber forest products is still limited, and few studies have contributed to the establishment of legal regulations for collection and management. With regard to target 13, which concerns traditional and indigenous knowledge about plant use and the dependence of these peoples on plants, there are still a lack of integrative and effective policy initiatives. However, considering the negative political context of recent decades and exacerbated in recent years in relation to biodiversity conservation and indigenous peoples and local communities, profound changes are necessary in the Brazilian scenario, with strong support and recognition for indigenous peoples and local communities, so that any objective related to the achievement of the goals of the GSPC is minimally achieved.
In this article I analyse how transcontinental migrations, the various forms that these took (Paleolithic first settlement, conquest and colonialism, slavery, free mass movements, and mercantile diasporas), and the way these interacted in the receiving environments, shaped the historical formation of Latin America. The article shows how these interactions explain the key apparent contradictions of Latin America: that it is both the most racially diverse and the most culturally homogeneous region in the world; that it has the highest crime/homicide rates but also the lowest levels of civil and international wars, holocausts, and other forms of collective violence; and that it has the highest levels of social inequality in the world but also some of its historically most egalitarian areas.
Conservation strategies aiming to safeguard species genetic diversity in the Cerrado are urgent. The biome is an agriculture frontier and lost at least 50% of its natural capital since the early 1950s, with the highest rate of vegetation clearing among all Brazilian biomes. Here we match information on geographic range shifts in response to climate changes and habitat loss to define conservation priorities for species genetic diversity using Eugenia dysenterica, a widely distributed tree across the Brazilian Cerrado. We found a set of 27 optimal solutions in which a minimum of 12 out of 23 populations are necessary to represent all 208 alleles of the species. Environmental suitability predicted for 2050 was higher for populations in the southern region of the Cerrado, whereas the proportion of natural remnants around populations expected for 2030 was lower in this same region. Thus, it seems to be more conservative to adopt “in situ” strategies in the northwestern part of the species range to hold more genetic diversity in areas harboring high numbers of natural remnants, despite the likely reduction in climatic suitability. On the other hand, in the southern and southeastern region of the range, despite more stability from a climatic point of view, there was a serious constraint given the high levels of human occupation; in this case, “ex situ” strategies might be a better option for the species. Our results and proposed priorities enable different strategies for making an operational approach for conservation of genetic diversity. Adopting different prioritization strategies for stable and unstable regions (both in climatic suitability and natural remnants) in the future would allow, in principle, to avoid “the worst of both worlds” to achieve an efficient conservation program for the species.
N.I. Vavilov was among the first scientists who recognized the high potential value of plant genetic resources (PGR) for humankind. In addition to his fundamental work on the centers of crop origin, he emphasized the importance of collection and ex situ conservation of cultivated plants and their wild relatives, to make them available for breeding programs and for future generations. Vavilov's ideas formed a solid scientific basis for the long-term efforts on securing PGR in ex situ genebanks, both internationally and in Russia. The collection of seeds and living plants at the N.I. Vavilov All Russian Institute of Plant Genetic Resources (VIR) is one of the oldest in the world. The size of the collection increased from 301 accessions in 1901 to over 330,000 accessions in 2017, now representing 64 botanical families, 376 genera, and 2169 species. Acquisition was mainly focused on crops that are suitable for cultivation in Russia such as potatoes, barley, wheat, sorghum, beans, vegetables, forage species, and many others. For over a century, VIR has been providing the materials for breeding programs and research, which resulted in developing new cultivars with unique characteristics such as high yield combined with deceased resistance, improved storability, cold and drought tolerance, or ability to grow on deserts and polluted lands. The main field collection near St. Petersburg and 11 main branches across the country covering a wide spectrum of climatic conditions combined with modern seed storage, in vitro and cryobank facilities, and molecular laboratories form a solid platform for breeding, regeneration, and evaluation of accessions in the collection. This article gives a brief overview of VIR as the leading genebank and breeding center in Russia, its main activities in conservation and utilization of PGR for national food security and its role in developing national policies in this area.
Knowing how microevolutionary processes, such as genetic drift and natural selection, shape variation in adaptive traits is strategic for conservation measures. One way to estimate local adaptation is to compare divergences in quantitative traits (QST) and neutral loci (FST). Therefore, we have assessed the pattern of phenotypic and molecular genetic divergence among natural subpopulations of the fruit tree Eugenia dysenterica DC. A provenance and progeny test was performed to assess the quantitative traits of the subpopulations collected in a wide distribution area of the species in the Brazilian Cerrado. The sampled environments are in a biodiversity hotspot with heterogeneous soil and climate conditions. By associating quantitative trait variation in initial seedling development with neutral microsatellite marker variation, we tested the local adaptation of the traits by the QST–FST contrast. Genetic drift was prevalent in the phenotypic differentiation among the subpopulations, although the traits seedling emergence time and root green mass, which are relevant for adaptation to the Cerrado climate, showed signs of uniform selection. Our results suggest that E. dysenterica has a spatial genetic structure divided into two large groups, separated by a line that divides the Cerrado biome in a southwestern to northeastern direction. This structure must be taken into account for managing E. dysenterica genetic resources both for conservation and breeding purposes.
Agro-biodiversity is seriously threatened worldwide and strategies to preserve it are dramatically required. We propose here a methodological approach aimed to identify areas with a high level of agro-biodiversity in which to set or enhance in situ conservation of plant genetic resources. These areas are identified using three criteria: Presence of Landrace diversity, Presence of wild species and Agro-ecosystem ecological diversity. A Restrictive and an Additive prioritization strategy has been applied on the entire Italian territory and has resulted in establishing nationwide 53 and 197 agro-biodiversity hotspots respectively. At present the strategies can easily be applied at a European level and can be helpful to develop conservation strategies everywhere.
Brazil has global importance for food production and conservation of natural resources. The country has plans to increase yields and commitments to decrease deforestation that require higher productivity. Plans and policies for the growth of Brazilian agriculture, however, have been made without an integrated analysis of the harvest and not supported by a universal metric regarding its efficiency. Applying methods to model flows of energy and matter along food supply chains for agricultural production from 1975 to 2006, we found that crop and cattle harvests and their productivity have increased during the last four decades in consolidated and deforestation frontier regions. Yet in 2006, crop protein production was 20 times larger than cattle protein, using an area 2.6 times smaller than pastures. Crop protein productivity was 0.25 ton.ha–1 with emissions of 2 ton GHG per ton of protein, while cattle productivity was 0.01 ton.ha–1 with emissions of 283 ton GHG per ton of protein. From 1975 to 2006, the portion of crop protein and energy going to feed increased while the portion going to direct human consumption decreased. Our findings suggest that more efficient food systems would be achieved by a combination of intensification of cattle systems, optimization of feed-meat systems and an increase in the share of the consumption of crops as a source of protein. We suggest an initial road map to the expansion of the cultivated area and intensification of agriculture for zero deforestation, efficient and sustainable land use and food systems where cattle pasture intensification is a transition that will last until the expansion of crops replace all pasture present on suitable arable land. During this transition, pasture area will decrease until it is limited only to marginal non-arable lands. Such change could be achieved by a robust strategy that combines penalties and incentives and prevents the risks of a rebound effect for the intensification of agriculture.
The eighteenth-century Malthusian prediction of population growth outstripping food production has not yet come to bear. Unprecedented agricultural land expansions since 1700, and technological innovations that began in the 1930s, have enabled more calorie production per capita than was ever available before in history. This remarkable success, however, has come at a great cost. Agriculture is a major cause of global environmental degradation. Malnutrition persists among large sections of the population, and a new epidemic of obesity is on the rise. We review both the successes and failures of the global food system, addressing ongoing debates on pathways to environmental health and food security. To deal with these challenges, a new coordinated research program blending modern breeding with agroecological methods is needed. We call on plant biologists to lead this effort and help steer humanity toward a safe operating space for agriculture. Expected final online publication date for the Annual Review of Plant Biology Volume 69 is April 29, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Community seed banks are an effective local institution to conserve quality
seeds, to strengthen farmers’ accessibility to social seed networks, and
improve agrobiodiversity and food security. This article analyses the
prospects and challenges of community seed banks in climate change
contexts. It finds that community seed banks serve as sources of climateresilient
seeds to withstand in local climates and improve community
resilience. Community seed banks provide landraces for participatory crop
improvement to develop resistant varieties to improve quality and
productivity. They also strengthen participatory seed exchange to cope
with climate adversity. However, there are challenges with defining
specific and common goals, functions, approaches, and governance.
For millennia, Amazonian peoples have managed forest resources, modifying the natural environment in subtle and persistent ways. Legacies of past human occupation are striking near archaeological sites, yet we still lack a clear picture of how human management practices resulted in the domestication of Amazonian forests. The general view is that domesticated forests are recognizable by the presence of forest patches dominated by one or a few useful species favored by long-term human activities. Here, we used three complementary approaches to understand the long-term domestication of Amazonian forests. First, we compiled information from the literature about how indigenous and traditional Amazonian peoples manage forest resources to promote useful plant species that are mainly used as food resources. Then, we developed an interdisciplinary conceptual model of how interactions between these management practices across space and time may form domesticated forests. Finally, we collected field data from 30 contemporary villages located on and near archaeological sites, along four major Amazonian rivers, to compare with the management practices synthesized in our conceptual model. We identified eight distinct categories of management practices that contribute to form forest patches of useful plants: (1) removal of non-useful plants, (2) protection of useful plants, (3) attraction of non-human animal dispersers, (4) transportation of useful plants, (5) selection of phenotypes, (6) fire management, (7) planting of useful plants, and (8) soil improvement. Our conceptual model, when ethnographically projected into the past, reveals how the interaction of these multiple management practices interferes with natural ecological processes, resulting in the domestication of Amazonian forest patches dominated by useful species. Our model suggests that management practices became more frequent as human population increased during the Holocene. In the field, we found that useful perennial plants occur in multi-species patches around archaeological sites, and that the dominant species are still managed by local people, suggesting long-term persistence of ancient cultural practices. The management practices we identified have transformed plant species abundance and floristic composition through the creation of diverse forest patches rich in edible perennial plants that enhanced food production and food security in Amazonia.
Background and aims:
Amazonia is a major world centre of plant domestication, but little is known about how the crops were dispersed across the region. Manioc (Manihot esculenta) was domesticated in the south-western Amazon basin, and is the most important staple food crop that originated in Amazonia. Current contrasting distributions may reflect distinct histories of dispersal of bitter and sweet manioc landraces. To produce new insights into the evolutionary history of the crop, we investigated the contemporary genetic diversity and structure of bitter and sweet manioc along major Amazonian rivers.
Methods:
The patterns of genetic structure and diversity of wild and cultivated sweet and bitter manioc with four chloroplast and 14 nuclear microsatellite markers were evaluated. Results were interpreted in terms of the crop's dispersal.
Key results:
No phylogeographic patterns among rivers were detected, and genetic structure among rivers was confounded by the bitter-sweet divergence. However, differences in the distribution of nuclear diversity and somewhat distinctive patterns of genetic structure across rivers were observed within bitter and sweet manioc.
Conclusions:
Various pre-Columbian and post-European conquest events in the history of Amazonian occupation may explain the absence of clearer patterns of genetic structure. However, the wide distribution of the most common chloroplast haplotype agrees with an early dispersal of manioc across Brazilian Amazonia. Furthermore, differences in genetic structure and in the spatial distribution of genetic diversity suggest that bitter and sweet manioc had distinct dispersal histories. Knowledge about how prehistoric and contemporary Amazonian peoples manage their crops is valuable for the maintenance and conservation of the impressive diversity of their native crops.
The objective of this study was to record the most important vegetal resources in the life of the quilombolas of Bocaina, emphasizing the practices of agrobiodiversity management. We used semi-strutured and informal interviews, free list, and participant observation. For records, we used a field diary, photos, and recordings. For analysis, we performed calculations of absolute and relative frequencies, linear regression analysis to verify relations between age and species richness, Detrended Correspondence Analysis (DCA), and diversity profile. We recorded a total of 180 species, of which, the most cited plants were food crops cultivated in backyards and clearings. Ninety-seven medicinal species used for various diseases were recorded. The most common form of use is leaf tea. We verified that the plants management is of agroecological character favoring biodiversity maintenance. We concluded that the Community, by means of its traditional knowledge, performs agroecological management of the plants, promoting food security for its family and conservation of genetic resources.
Background
Common bean is a legume of social and nutritional importance as a food crop, cultivated worldwide especially in developing countries, accounting for an important source of income for small farmers. The availability of the complete sequences of the two common bean genomes has dramatically accelerated and has enabled new experimental strategies to be applied for genetic research. DArTseq has been widely used as a method of SNP genotyping allowing comprehensive genome coverage with genetic applications in common bean breeding programs.
Results
Using this technology, 6286 SNPs (1 SNP/86.5 Kbp) were genotyped in genic (43.3%) and non-genic regions (56.7%). Genetic subdivision associated to the common bean gene pools (K = 2) and related to grain types (K = 3 and K = 5) were reported. A total of 83% and 91% of all SNPs were polymorphic within the Andean and Mesoamerican gene pools, respectively, and 26% were able to differentiate the gene pools. Genetic diversity analysis revealed an average HE of 0.442 for the whole collection, 0.102 for Andean and 0.168 for Mesoamerican gene pools (FST = 0.747 between gene pools), 0.440 for the group of cultivars and lines, and 0.448 for the group of landrace accessions (FST = 0.002 between cultivar/line and landrace groups). The SNP effects were predicted with predominance of impact on non-coding regions (77.8%). SNPs under selection were identified within gene pools comparing landrace and cultivar/line germplasm groups (Andean: 18; Mesoamerican: 69) and between the gene pools (59 SNPs), predominantly on chromosomes 1 and 9. The LD extension estimate corrected for population structure and relatedness (r²SV) was ~ 88 kbp, while for the Andean gene pool was ~ 395 kbp, and for the Mesoamerican was ~ 130 kbp.
Conclusions
For common bean, DArTseq provides an efficient and cost-effective strategy of generating SNPs for large-scale genome-wide studies. The DArTseq resulted in an operational panel of 560 polymorphic SNPs in linkage equilibrium, providing high genome coverage. This SNP set could be used in genotyping platforms with many applications, such as population genetics, phylogeny relation between common bean varieties and support to molecular breeding approaches.
Electronic supplementary material
The online version of this article (doi:10.1186/s12864-017-3805-4) contains supplementary material, which is available to authorized users.
This study describes the genetic diversity and population structure of 194 native maize populations from 23 countries of Latin America and the Caribbean. The germplasm, representing 131 distinct landraces, was genetically characterized as population bulks using 28 SSR markers. Three main groups of maize germplasm were identified. The first, the Mexico and Southern Andes group, highlights the Pre-Columbian and modern exchange of germplasm between North and South America. The second group, Mesoamerica lowland, supports the hypothesis that two separate human migration events could have contributed to Caribbean maize germplasm. The third, the Andean group, displayed early introduction of maize into the Andes, with little mixing since then, other than a regional interchange zone active in the past. Events and activities in the pre- and post-Columbian Americas including the development and expansion of pre-Columbian cultures and the arrival of Europeans to the Americas are discussed in relation to the history of maize migration from its point of domestication in Mesoamerica to South America and the Caribbean through sea and land routes.
The Brazil historically prioritized the model of ex situ conservation held in cold storage, in vitro conservation and living collections in the field. This type of conservation captures the evolutionary moment in which the collection was made, but plants not continue the evaluation. This characteristic reveals the limitations of this type of conservation to provide faster answers in a time of crisis related to environmental changes, for example. Currently, FAO recognizes that genetic diversity should be maintained not only in genebanks as well as in local agricultural systems, where the participation of farmers is crucial. The ITPGRFA binding, instrument signed by Brazil in 2001, makes this a line of action and research required for all members. But how to implement it? In this paper, we present a reflection on the complementarities between the models of ex situ conservation and on farm, taking the proposed ‘shared management of ex situ collections’ as example of incipient process of construction, the scientific and institutional paths that enable new ways of interaction between traditional farmers and agricultural research institutions, in order to preserve not only the germplasm, but also processes that generate agrobiodiversity.
Among the agricultural environments of traditional communities, home gardens are frequently cited as high agrobiodiversity sites. However, the agrobiodiversity of home gardens along a rural-urban gradient demands study in order to identify possible influences of urbanization and to support mitigation of impacts. The present work investigated the role home gardens play in the in situ agrobiodiversity conservation of plants in quilombola communities with different degrees of urbanization. The study found that more urbanized communities have larger home gardens, but the average richness of plant species in these areas was not statistically different among the communities. Furthermore, the abundance of plant species was similar. Medicinal and food plants were mainly found in home gardens of the communities with high to intermediate levels of urbanization, while ornamental plants were more common in rural community home gardens. It is believed that crop exclusivity in home gardens of the more urbanized communities highly influenced the results, increasing the role home gardens play in maintaining traditional practices. The elevated and statistically equal species richness in home gardens suggests that, despite the factors generated by urbanization, all of the communities are very important for in situ conservation of native and introduced species.
This study aimed to evaluate the genetic and cytological diversity and stability of 35 cherry tree accessions collected in Rio Grande do Sul. We used 15 RAPD (Random Amplified Polymorphic DNA) molecular markers and performed cytological analysis and number count of anthers. Analyses of genetic diversity allowed the separation of accessions into four groups, resulting in an average of 8.93 bands per primer amplified, 7.89 polymorphic bands, 88.08% of poly¬morphism and 86% of genetic similarity. Cytological analyses of gametic cells allowed for the characterization of accessions as diploids with n=11. In these, the average of meiotic cells considered normal was 82.12%; average pollen vi¬ability was 92.44% and in vitro germination was 40.26%; the average number of anthers was 161.85 anthers/flowers. Therefore, the accessions evaluated showed high genetic similarity and cytological stability and can be used in commercial plantations or hybridizations.
This text presents the seven articles that forms the dossier, stressing its common bases and some of its particularities.
‘Microcenters of diversity’ are restricted geographical areas within which a significant diversity of genetic resources is accumulated. Maize genetic variability, one of the largest among cultivated species, particularly in far western Santa Catarina, southern Brazil, has shown a rich store of landraces, conserved on farm by small-scale farmers. Thus, this study aimed to characterize the diversity of Zea mays L. landraces in two municipalities of this micro-region in Santa Catarina, as well as its geographic distribution, developing the census of diversity as a methodological proposal. Diagnosis was made according to the farmers’ knowledge. The field survey was conducted in 70 rural communities involving 2049 farms. The methodology allowed identifying 136 populations of wild relatives, of which some belong to the species Zea luxurians (Durieu and Ascherson) Bird, and 1513 populations of maize landraces, comprising 1078 of popcorn, 337 of common maize, 61 of sweet maize and 37 of flour maize. The identification of 59 morphological groups, the high use, adaptive and agronomic values, and the Shannon index (H′), estimated according to the grain shape (0.79), endosperm type (0.73), size (0.87), color (1.40), and morphological group (3.16), showed at set a considerable diversity distribution conserved on farm in this micro-region. Landrace richness and the presence of wild relative species, associated with the local human activity and sociocultural aspects, allowed to characterize the far western Santa Catarina as a ‘microcenter of diversity’ of Zea mays L.
Eugenia dysenterica DC. (Myrtaceae) is a perennial tree producing edible fruits and ornamental flowers of potential value widely distributed in Brazilian "Cerrados" (savannas), but available genetic resources and potential for future breeding programs must be evaluated. Here we evaluated the reproductive system and pollen-mediated gene flow in one generation of Eugenia dysenterica germplasm collection of Agronomy School, Federal University of Goiás (in Goiânia city, Central Brazil). We collected leaves from all adults from the germplasm collection (682 plants) and seeds (542) from 23 mother-trees. Genotypes were obtained for seven microsatellite loci. Genetic diversity was high and did not significantly differ between adults (H e = 0.777) and progeny arrays (H e = 0.617). Our results showed that E. dysenterica has an allogamous mating system in the germplasm collection (t m = 0.957), but with high and significant biparental inbreeding (t m - t s = 0.109). Because sibs are very close to each other, mating between closely related individuals is likely. Paternity correlation was also relatively high, indicating a 11.9 % probability that a randomly chosen pair of outcrossed progeny from the same array are full sibs. The maximum pollen dispersal distance (224 m), estimated using assignment test, corresponded to the boundaries of the orchard. We were able to assign the paternity to only 64 % of the 349 seeds analyzed, indicating potential pollen immigration to the germplasm collection. The variance effective population size estimated for one maternal family in the germplasm collection (N ev = 3.42) is very close to the theoretical maximum value for half-sibs (Nev = 4.0). Because E. dysenterica has a long life cycle and generation time, the maintenance of an effective population size of at least 100 in the germplasm collection is suggested, which can be achieved by maintaining a seed-trees number around 30 individuals.
Conservation strategies routinely use optimization methods to identify the smallest number of units required to represent a set of features that need to be conserved, including biomes, species, and populations. In this study, we provide R scripts to facilitate exhaustive search for solutions that represent all of the alleles in networks with the smallest possible number of populations. The script also allows other variables to be added to describe the populations, thereby providing the basis for multi-objective optimization and the construction of Pareto curves by averaging the values in the solutions. We applied this algorithm to an empirical dataset that comprised 23 populations of Eugenia dysenterica, which is a tree species with a widespread distribution in the Cerrado biome. We observed that 15 populations would be necessary to represent all 249 alleles based on 11 microsatellite loci, and that the likelihood of representing all of the alleles with random networks is less than 0.0001. We selected the solution (from two with the smallest number of populations) obtained for the populations with a higher level of climatic stability as the best strategy for in situ conservation of genetic diversity of E. dysenterica. The scripts provided in this study are a simple and efficient alternative to more complex optimization methods, especially when the number of populations is relatively small (i.e. <25 populations).
Plant breeding is one way to confront the challenge of bridging the widening gap between the demand and supply of food. Despite the importance, however, plant breeding has its own negative side effects. The replacement of landraces with a few genetically uniform varieties depletes genetic diversity and provides ideal conditions for diseases and insect pests that called genetic vulnerability. The increasingly growing human population and the subsequently rising de- mands for more food, on the one hand, and the success of such efforts like the "Green Revolution" from adoption of ge- netically uniform varieties in many parts of the world, on the other, are the main driving force towards this narrow genetic base. It is, therefore, important to understand the phenomena and plan to minimize the risks from genetic vulnerability. Under marginal conditions where resource-poor farmers dominate, the current plant breeding strategies, variety release, registration and certification procedures leading to genetic uniformity should be reconsidered and some level of genetic diversity should deliberately be maintained in variety development programs. Genetic diversity can be introduced at different levels and in different ways which may include intra-varietal, inter-varietal, inter-parental and inter-specific diversities. Breeding for specific adaptation instead of wide adaptation, systematic spatial and temporal gene deployment, use of inter-specific varietal mixtures and integration of horizontal and vertical resistances have been suggested as solutions.
Usually known as jenipapo, Genipa americana L. is a Rubiaceae Brazilian native species. It is an important species in the restoration of Brazilian riparian forests and is one of the most promising fruit trees for sustainable harvesting programs. In this study we provide the first data on the genetic diversity and structure of a Jenipapo Germplasm Bank using inter simple sequence repeat (ISSR) markers. We evaluated 160 accessions from wild populations, and the data generated from 12 ISSR primers were used to determine genetic variability via a model-based Bayesian procedure (Structure) and molecular variance analysis. In addition, Shannon index, genetic diversity and Jaccard coefficients were estimated. A total of 12 primers were used, which generated 123 polymorphic fragments. Four groups were formed from the analysis of the fragments, and the CR1-2 genotype was isolated, being more divergent than the other genotypes.
Population Biology of Palm Heart (Euterpe edulisMartius–Arecaceae) in Managed Landscape Units in Southern Brazil. The use of natural areas throughout history has created landscape mosaics. The landscape units assessed in this study on Euterpe edulis populations in southern Brazil consisted of secondary forests, rural homegardens, and sites inside a protected area (PA). Our goal was to compare the level of conservation of E. edulis populations in three landscape units in order to verify the influence of management practices. Twelve homegardens, four areas in secondary forests in rural properties, and several areas in a sustainable use PA were assessed. Population structure differed among the three groups of landscape units. The population density of E. edulis was higher in smaller size classes (seedling, young I) in the PA and in larger size classes (reproductive) in homegardens, whereas both situations occurred in secondary forests. Genetic divergence varied 0.001 and 0.0023 between landscape groups. The highest variation in genetic diversity indexes was recorded in homegardens, with the presence of alleles that were not found in the protected area. Genetic diversity indexes varied less in the protected area, while the average values were higher in secondary forests. We therefore concluded that the sites assessed outside protected areas also contribute to the conservation of this palm species.
This study revealed the profile of common bean farmers in the state of Rio de Janeiro, Brazil. One hundred and thirty-eight farmers from 24 municipalities were interviewed. We observed that common beans are a key component of agricultural systems in this state, with the number of varieties managed by family varying widely (from one to 11). This variation was influenced by socioeconomic, ecogeographic, and cultural factors. An impressive number of common bean varieties were being managed by farmers who resided at mid-altitude zones and combine subsistence crops with market-oriented cultivation. In three of five mesoregions visited, the traditional agriculture has been affected by climate changes. The majority of farmers who managed low diversity of common beans, and all farmers who stopped growing this crop in recent years resided in these regions. Facing the risk of genetic erosion, farmers, researchers and extension workers involved in this research are building strategies to strengthen the conservation of this local germplasm. Actions are underway with public agencies to enhance the importance of self-consumption cultures for food security, local development and conservation of cultural traditions. Among these, we highlight the publication of Catálogo da Diversidade Feijão-comum do estado do Rio de Janeiro. In addition, an ex-situ conservation agreement was established for the varieties, with a strong participation of custodians, to provide greater security to the local common bean germplasm.
The complexity of maize domestication
Maize originated in what is now central Mexico about 9000 years ago and spread throughout the Americas before European contact. Kistler et al. applied genomic analysis to ancient and extant South American maize lineages to investigate the genetic changes that accompanied domestication (see the Perspective by Zeder). The origin of modern maize cultivars likely involved a “semidomesticated” lineage that moved out of Mexico. Later improvements then occurred among multiple South American populations, including those in southwestern Amazonia.
Science , this issue p. 1309 ; see also p. 1246
We studied the genetic diversity and spatial genetic structure (SGS) of adult and juvenile individuals in a population of Hancornia speciosa in Central-West Brazil. For this, we sampled and mapped 113 adults and 100 juveniles in an area of 2.5 ha. Genomic DNA was obtained from leaves and seven microsatellite loci were used to genotype all individuals. The studied population showed high genetic diversity (He) but with significant inbreeding (f) for both life stages most likely due to biparental inbreeding. Spatial genetic structure was weak for both life stages and the values of SP were low and neighborhoods (Nb) was high for both generations showing a potential long-distance gene dispersal.
Yams (
Dioscorea
spp.) are one of the main root and tuber crops in the world, especially within the species complex
Dioscorea cayenensis
/
D. rotundata
. Few studies have been conducted in Brazil with these species, including genetic diversity. The objective of this study was to characterize the genetic diversity of local varieties of
D. cayenensis
and
D. rotundata
using morphological and molecular markers, and provide information on the management and use of the crop by family farmers from different regions in Brazil. Thus, yam tubers were sampled from several municipalities in the South, Southeast and Northeast regions. Eighteen morphological traits and ten microsatellite loci were used to analyse 47 yam accessions (23
D. cayenensis
and 24
D. rotundata
). Species identification was carried out after field morphological evaluation. Spatial genetic analysis indicated significant structure among the local varieties, mostly between regions and species. Both cluster and Bayesian analyses showed a separation of the accessions into two distinct groups: group I with accessions originated from the Southeast region and group II with accessions originated from the Northeast region, while accessions from the South region were intermediate or included in either group. The results showed a separation between
D. cayenensis
and
D. rotundata
accessions in Brazil, and that
D. cayenensis
occurs predominantly in the Southeast region, while
D. rotundata
occurs in the Northeast region. Further studies with larger sampling would be welcome in order to confirm these findings. Also, this study highlights the importance of family farmers in the genetic diversity conservation of these species in Brazil.
Immigration, Ethnicity, and National Identity in Brazil, 1808 to the Present examines the immigration to Brazil of millions of Europeans, Asians, and Middle Easterners beginning in the nineteenth century. Jeffrey Lesser analyzes how these newcomers and their descendents adapted to their new country and how national identity was formed as they became Brazilians along with their children and grandchildren. Lesser argues that immigration cannot be divorced from broader patterns of Brazilian race relations, as most immigrants settled in the decades surrounding the final abolition of slavery in 1888 and their experiences were deeply conditioned by ideas of race and ethnicity formed long before their arrival. This broad exploration of the relationships between immigration, ethnicity, and nation allows for analysis of one of the most vexing areas of Brazilian study: identity.