scholarly journals La domesticación de Stenocereus stellatus (Pfeiffer) Riccobono (Cactaceae)

2017 ◽  
pp. 129
Author(s):  
Alejandro Casas ◽  
Alfonso Valiente-Banuet ◽  
Javier Caballero
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Reproductive System ◽  
Home Gardens ◽  
Morphological Divergence ◽  
Wild Populations ◽  
Silvicultural Management ◽  
Stenocereus Stellatus ◽  
Cultivated Populations

This study aimed at analyzing processes of domestication by silvicultural forms of management. The effects of artificial selection on morphology and reproductive biology of Stenocereus stellatus are analyzed in wild; wild-managed in situ (silvicultural management) and cultivated populations from the Tehuacan Valley and La Mixteca Baja. People select the phenotypes of this columnar cactus species with relatively larger and sweeter fruits with thinner peel and fewer spines, favoring their numbers in wild populations managed in situ as well as in home gardens. Favorable phenotypes prevail in wild populations managed in situ, indicating that artificial selection has had significant effects under this form of management. These phenotypes are especially abundant in home gardens, which suggests that artificial selection is even stronger under cultivation. Favorable phenotypes are scarce or absent in non-manipulated wild populations. Such morphological divergence is maintained despite the reproductive system of S. stellatus, is self-incompatible in all populations, and even when there were not found spatial and temporal barriers for pollen flow between wild and cultivated populations. Abundance of favorable phenotypes in areas managed by people may be explained by action of artificial selection, while absence of some domesticated phenotypes in wild populations seems to be due to pollen incompatibility between some cultivated phenotypes and wild populations, but it could also be due to pressures of natural selection against cultivated phenotypes.

scholarly journals Manejo de la vegetación, domesticación de plantas y origen de la agricultura en Mesoamérica

2017 ◽  
pp. 31 ◽  
Author(s):  
Alejandro Casas ◽  
Javier Caballero ◽  
Cristina Mapes ◽  
Sergio Zárate
Keyword(s):  
Plant Communities ◽  
Artificial Selection ◽  
Plant Management ◽  
Useful Plants ◽  
Plant Populations ◽  
Stenocereus Stellatus ◽  
Morphological Differences ◽  
Anoda Cristata ◽  
Incipient Domestication

A model of domestication of  plants in Mesoamerica based  on  selective management  of  plant populations and  communities by silvicultural practices is analyzed. Archaeological and  ethnobotanical information  suggests that  intentional manipulation of vegetation by Mesoamerican peoples has occurred in  past  and present times  in  order to  control availability  of  useful  plants. Forms of  management of  plant communities or  populations have  included tolerance, protection and  enhancement of individual  plants of  particular species  during clearance of  vegetation and  other ways of  perturbation. Processes of  artificial selection  (selection  in situ) may be carried out  through these  forms  of plant  management. These processes may cause significant morphological differences between wild and  managed populations as illustrated by the  cases  discussed here of  Anoda  cristata,  Crotalaria pumila,  Leucaena esculenta and  Stenocereus stellatus. Processes of artificial selection in  situ are mechanisms of  incipient domestication of  plants which  appear to  have  been   carried out  in Mesoamerica, perhaps since pre-agricultural times,  and  that  could contribute  to explain the processes that  led to  the  origins of agriculture in this region.

Indirect estimates reveal the potential of transgene flow in the crop–wild–weed Sorghum bicolor complex in its centre of origin, Ethiopia

2016 ◽  
Vol 15 (6) ◽  
pp. 496-505
Author(s):  
Asfaw Adugna ◽  
Endashaw Bekele
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Phenotypic Traits ◽  
Wild Populations ◽  
Centre Of Origin ◽  
Transgene Flow ◽  
Potential Risks ◽  
Cultivated Populations ◽  
Simple Sequence

AbstractA study was carried out between 2008 and 2011 to investigate the potential risks of gene flow and its consequences in the crop–wild–weed S. bicolor complex in Ethiopia to aid efforts to conserve genetic diversity. Morphological measurements and genomic DNA samples were taken in situ from 30 wild and eight cultivated populations representing a total of 760 samples from five regions. Genetic diversity, gene flow, population structure and outcrossing rates of wild populations were computed using phenotypic measurements and/or polymorphic simple sequence repeat (SSR) markers. Moreover, morphological analyses of fitness of crop–wild hybrids were studied. High diversity was observed among the wild/weedy sorghum populations for phenotypic traits and SSRs. SSR diversity was high in both wild and cultivated populations, but the magnitude was greater in the former. Gene flow between the wild and the cultivated sorghum was observed to be higher than that within either pool. Wild sorghums exhibited variation in the multilocus outcrossing rate (range = 0.31–0.65) and fitness was not compromised in most wild × crop hybrids. The study indicated that crop-to-wild gene flow is possible in Ethiopia. Thus, genes from transgenic sorghum are expected to enter into the wild and non-transgenic cultivated populations and may spread and persist, if transgenic sorghum is deployed in Ethiopia and in other countries of Africa, which may pose risk of introduction of unwanted effects, which in turn may lead to loss of genetic diversity.

scholarly journals Evolution under domestication of correlated characters in populations of Stenocereus stellatus (Pfeiff.) Riccob., under different forms of management in central Mexico: genetic diversity, damage, and defense mechanisms

2021 ◽  
Author(s):  
Verónica Patiño-López ◽  
David Bravo-Avilez ◽  
Carlos F. Vargas-Mendoza ◽  
José Blancas ◽  
Beatriz Rendón-Aguilar
Keyword(s):  
Genetic Diversity ◽  
Defense Mechanisms ◽  
Central Mexico ◽  
Damage Level ◽  
Stenocereus Stellatus ◽  
Domestication Process ◽  
Cultivated Populations ◽  
Correlated Characters ◽  
Human Selection

AbstractAcross the process of domestication, human selection produces changes in target attributes as well as changes that are not necessarily desired by humans due to pleiotropic or linked genes. In this paper we addressed, correlated changes between genetic diversity, damage level, defense mechanisms (resistance and tolerance), and fitness due to the domestication process of Stenocereus pruinosus (Otto ex Pfeiff.) Buxbaum and Stenocereus stellatus (Pfeiff.) Riccobono, an endemic columnar cactus of south-central Mexico. One hundred eighty individuals of S. stellatus from wild, in situ managed, and cultivated populations of Valle de Tehuacán and Mixteca Baja, Puebla, were sampled, and attributes including damage level, defense mechanisms and fitness (number of fruits) were measured. The DNA of 176 individuals was extracted to amplify and analyze five microsatellites in order to estimate genetic diversity and structure. As expected, cultivated populations showed a significantly higher damage level, as well as lower resistance and genetic diversity. Depending on the form of management, correlations between genetic diversity and the rest of the attributes exhibited different patterns. In wild populations, genetic diversity was positively correlated with damage and negatively with resistance; in situ managed populations exhibited the opposite pattern, and in cultivated populations, no correlations were found between these attributes. We propose a hypothetic model of human selection to explain the variation in these correlations. No differences in genetic diversity and tolerance were detected between regions; however, the populations of Valle de Tehuacán exhibited more damage and more resistance. In both regions, populations showed a positive correlation between fitness and resistance and a negative correlation between damage and resistance, suggesting the existence of a defense mechanism to ensure fitness. Also, non-regional differentiation suggests an eventual gene flow due to pollinators, human movement of branches, or a common ancestry before the domestication process.

Fatal asymmetries

2021 ◽  
pp. 1-15
Author(s):  
Luis Sánchez
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Political Institutions ◽  
Charles Darwin ◽  
The Impact ◽  
Descent Of Man

Abstract In Descent of Man, Charles Darwin noted the impact of political institutions on natural selection. He thought that institutions such as asylums or hospitals may deter natural selection; however, he did not reach a decisive answer. Questions remain as to whether the selective impacts of political institutions, which in Darwin’s terms may be referred to as “artificial selection,” are compatible with natural selection, and if so, to what extent. This essay argues that currently there appears to be an essential mismatch between nature and political institutions. Unfitted institutions put exogenous and disproportionate pressures on living beings. This creates consequences for what is postulated as the condition of basic equivalence, which allows species and individuals to enjoy similar chances of survival under natural circumstances. Thus, contrary to Darwin’s expectations, it is sustained that assumed natural selection is not discouraged but becomes exacerbated by political institutions. In such conditions, selection becomes primarily artificial and perhaps mainly political, with consequences for species’ evolutionary future.

scholarly journals Identification of medicinal plant Schisandra chinensis using a potential DNA barcode ITS2

2013 ◽  
Vol 82 (4) ◽  
pp. 283-288 ◽  
Author(s):  
Xian-kuan Li ◽  
Bing Wang ◽  
Rong-chun Han ◽  
Yan-chao Zheng ◽  
Hai-bo Yin Yin ◽  
...  
Keyword(s):  
Dna Barcode ◽  
Population Level ◽  
Species Level ◽  
Its2 Region ◽  
Schisandra Chinensis ◽  
Success Rates ◽  
Wild Populations ◽  
Efficient Tool ◽  
Different Populations ◽  
Cultivated Populations

To test whether the internal transcribed spacer 2 (ITS2) region is an effective marker for using in authenticating of the <em>Schisandra chinensis</em> at the species and population levels, separately. And the results showed that the wild populations had higher percentage of individuals that had substitution of C→A at site 86-bp than the cultivated populations. At sites 10-bp, 37-bp, 42-bp and 235-bp, these bases of the <em>Schisandra sphenanthera</em> samples differed from that of <em>S. chinensis</em>. Two species showed higher levels of inter-specific divergence than intra-specific divergence within ITS2 sequences. However, 24 populations did not demonstrate much difference as inter-specific and intra-specific divergences were concerned. Both <em>S. chinensis</em> and <em>S. sphenanthera</em> showed monophyly at species level, yet the samples of different populations shown polyphyly at population level. ITS2 performed well when using BLAST1 method. ITS2 obtained 100% identification success rates at the species level for <em>S. chinensis</em>, with no ambiguous identification at the genus level for ITS2 alone. The ITS2 region could be used to identify <em>S. chinensis</em> and <em>S. sphenanthera</em> in the “Chinese Pharmacopoeia”. And it could also correctly distinguish 100% of species and 100% of genera from the 193 sequences of <em>S. chinensis</em>. Hence, the ITS2 is a powerful and efficient tool for species identification of <em>S. chinensis</em>.

The relationship between facial whorl direction and sidedness in ridden horses

2006 ◽  
Vol 35 ◽  
pp. 247-250
Author(s):  
H. Randle ◽  
E. Elworthy
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Competitive Ability ◽  
Close Association ◽  
Human Behaviour ◽  
Physical Ability ◽  
Facial Hair ◽  
Selection For ◽  
The Relationship ◽  
The Brain

The influence of Natural Selection on the evolution of the horse (Equus callabus) is minimal due to its close association with humans. Instead Artificial Selection is commonly imposed through selection for features such as a ‘breed standard’ or competitive ability. It has long been considered to be useful if indicators of characteristics such as physical ability could be identified. Kidd (1902) suggested that the hair coverings of animals were closely related to their lifestyle, whether they were active or passive. In 1973 Smith and Gong concluded that hair whorl (trichloglyph) pattern and human behaviour is linked since hair patterning is determined at the same time as the brain develops in the foetus. More recently Grandin et al. (1995), Randle (1998) and Lanier et al. (2001) linked features of facial hair whorls to behaviour and production in cattle. Hair whorl features have also been related to temperament in equines (Randle et al., 2003).

scholarly journals Evidence of between-population differences in natural selection on extra-floral nectaries of the shrub Anemopaegma album (Bignoniaceae)

Botany ◽  
2016 ◽  
Vol 94 (3) ◽  
pp. 201-213
Author(s):  
Anselmo Nogueira ◽  
Pedro J. Rey ◽  
Julio M. Alcántara ◽  
Lúcia G. Lohmann
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Evolutionary Ecology ◽  
Common Garden ◽  
Phenotypic Selection ◽  
Population Differences ◽  
Wild Populations ◽  
Neotropical Savanna ◽  
Foliar Damage ◽  
Floral Nectaries

Extra-floral nectaries (EFNs) are thought to represent protective adaptations against herbivory, but studies on the evolutionary ecology of EFNs have seldom been conducted. Here we investigate the patterns of natural selection and genetic variation in EFN traits in two wild populations of Anemopaegma album Mart. ex DC. (Bignoniaceae) that have been previously described as contrasting EFN – ant adapted localities in the Neotropical savanna (Cristália and Grão Mogol). In each population, four EFN descriptors, foliar damage, and reproductive success variables were measured per plant (100–120 plants per population). To estimate the heritability of EFN traits, we crossed reproductive plants in the field, and grew offspring plants in a common garden. The results showed that ant assemblages differed between populations, as did the range of foliar herbivory. Genetic variation and positive phenotypic selection in EFN abundance were only detected in the Cristália population, in which plants with more EFNs were more likely to reproduce. An evaluation of putative causal links conducted by path analysis corroborated the existence of phenotypic selection on EFNs, which was mediated by the herbivory process in the Cristália population. While EFNs could be currently under selection in Cristália, it is possible that past selection may have driven EFN traits to become locally adapted to the local ant assemblage in the Grão Mogol population.

scholarly journals Two different epigenetic pathways detected in wild three-spined sticklebacks are involved in salinity adaptation

2019 ◽  
Author(s):  
Melanie J. Heckwolf ◽  
Britta S. Meyer ◽  
Robert Häsler ◽  
Marc P. Höppner ◽  
Christophe Eizaguirre ◽  
...  
Keyword(s):  
Natural Selection ◽  
Gasterosteus Aculeatus ◽  
Natural Populations ◽  
Wild Populations ◽  
Epigenetic Marks ◽  
Transgenerational Plasticity ◽  
The Face ◽  
Adaptation Processes ◽  
Methylation Patterns ◽  
Rapid Emergence

AbstractWhile environmentally inducible epigenetic marks are discussed as one mechanism of transgenerational plasticity, environmentally stable epigenetic marks emerge randomly. When resulting in variable phenotypes, stable marks can be targets of natural selection analogous to DNA sequence-based adaptation processes. We studied both postulated pathways in natural populations of three-spined sticklebacks (Gasterosteus aculeatus) and sequenced their methylomes and genomes across a salinity cline. Consistent with local adaptation, populations showed differential methylation (pop-DMS) at genes enriched for osmoregulatory processes. In a two-generation experiment, 62% of these pop-DMS were insensitive to salinity manipulation, suggesting that they could be stable targets for natural selection. Two-thirds of the remaining inducible pop-DMS became more similar to patterns detected in wild populations from the corresponding salinity, and this pattern accentuated over consecutive generations, indicating a mechanism of adaptive transgenerational plasticity. Natural DNA methylation patterns can thus be attributed to two epigenetic pathways underlying the rapid emergence of adaptive phenotypes in the face of environmental change.

scholarly journals A SIMULATION STUDY OF TRUNCATION SELECTION FOR A QUANTITATIVE TRAIT OPPOSED BY NATURAL SELECTION

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 989-1000
Author(s):  
Francis Minvielle
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Random Mating ◽  
Selection Response ◽  
Quantitative Character ◽  
Mass Selection ◽  
Frequency Selection ◽  
Selection Experiments ◽  
Selection For ◽  
Selective Process

ABSTRACT A quantitative character controlled at one locus with two alleles was submitted to artificial (mass) selection and to three modes of opposing natural selection (directional selection, overdominance and underdominance) in a large random-mating population. The selection response and the limits of the selective process were studied by deterministic simulation. The lifetime of the process was generally between 20 and 100 generations and did not appear to depend on the mode of natural selection. However, depending on the values of the parameters (initial gene frequency, selection intensity, ratio of the effect of the gene to the environmental standard deviation, fitness values) the following outcomes of selection were observed: fixation of the allele favored by artificial selection, stable nontrivial equilibrium, unstable equilibrium and loss of the allele favored by artificial selection. Finally, the results of the simulation were compared to the results of selection experiments.

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