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.

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.

Sandsitermes gen. nov., a new nasute termite genus from South America (Isoptera, Termitidae, Nasutitermitinae)

Zootaxa ◽  
2017 ◽  
Vol 4221 (5) ◽  
pp. 562
Author(s):  
CAROLINA CUEZZO ◽  
ELIANA M. CANCELLO ◽  
TIAGO F. CARRIJO
Keyword(s):  
South America ◽  
New Genus ◽  
Taxonomic Decision ◽  
Morphological Differences ◽  
Worker Castes ◽  
First Time

We establish herein a new genus of Neotropical termites of the subfamily Nasutitermitinae, Sandsitermes gen. nov.. The new genus accommodates a previously described species, Nasutitermes robustus (Holmgren), and is diagnosed by worker characters, including the mandibles, the gut-coiling configuration in situ, and the pattern of cushions and spines of the enteric valve. We characterized and illustrated the imago for the first time and redescribe the soldier and worker castes of Sandsitermes robustus gen. et comb. nov. from syntypes and other samples from eastern Peru. We support our taxonomic decision, presenting morphological differences between the gut pattern and enteric valve of S. robustus and 13 neotropical Nasutitermes species studied for this report, and discuss possible relationships with other neotropical nasute termites. 

scholarly journals Moulding the ideal crab: implications of phenotypic plasticity for crustacean stock enhancement

2020 ◽  
Author(s):  
Benjamin J Daly ◽  
Ginny L Eckert ◽  
W Christopher Long
Keyword(s):  
Phenotypic Plasticity ◽  
Large Scale ◽  
Field Studies ◽  
Stock Enhancement ◽  
Adaptive Responses ◽  
Ecological Performance ◽  
Significant Research ◽  
Morphological Differences ◽  
Plastic Responses

Abstract Numerous examples of behavioural and morphological differences between hatchery-cultured and wild individuals exist for a range of crustacean species; however, we submit that these variances are not deficiencies, but rather are adaptive responses to an unnatural rearing environment that may be detrimental in the natural environment. This phenotypic plasticity could be beneficial for stock enhancement because such plasticity suggests potential for change with adjustments to rearing protocols to achieve improved ecological competence. We examine how specific plastic responses can affect crustacean ecology through effects on predation, foraging, competition, and reproduction. For developing stock enhancement programmes, we recommend consideration of plastic phenotypic patterns before large-scale releases are initiated. Researchers can identify environmental factors that cue plasticity during hatchery rearing, determine if induced responses are ecologically influential after release into the wild, and examine the temporal scale on which phenotypic plasticity operates. Communal hatchery rearing at low-to-medium stocking densities with predator cues and natural substrates along with in situ conditioning, releases during periods of low predation risk, and coupled laboratory-field studies can contribute to improved ecological performance during stock enhancement. Finally, presentation of non-significant research results is needed to avoid bias towards hatchery–wild differences and help guide future conditioning programmes.

Morphological Characterization of Chitosan in the Hydroxyapatite/Chitosan Nanocomposites

2009 ◽  
Vol 79-82 ◽  
pp. 1675-1678
Author(s):  
Xiao Ying Lu ◽  
Xiu Hong Wang ◽  
Jian Xin Wang ◽  
Shu Xin Qu ◽  
Jie Weng
Keyword(s):  
Ph Value ◽  
Biomedical Application ◽  
Morphological Characterization ◽  
Layer By Layer ◽  
Oriented Growth ◽  
Hydrothermal Temperature ◽  
Morphological Differences ◽  
Hydrothermal Precipitation

The morphological differences of chitosan (CS) in the hydroxyapatite (HA)/CS nanocomposites were investigated in detailed, which were prepared via in situ hydrothermal precipitation. The results show that the obtained nanocomposites have excellent crystallinity and the crystal has excellent ordered structure, which is important to the composites performances in the biomedical application. Moreover, the CS arrangement and crystallinity in the composites greatly depend on the hydrothermal temperature and the pH value of precipitating agent. The temperature ranging from 373 to 413K and pH value of precipitating agent ranging from 12 to 14 were favorable to the crystallization and oriented growth of CS molecules in the composites. The CS crystals with better arrangement are assembled in the order of layer-by-layer in these composites.

In Situ extraction of rhizosphere organic compounds from contrasting plant communities

2000 ◽  
Vol 31 (5-6) ◽  
pp. 725-742 ◽  
Author(s):  
Caitlin C. Morse ◽  
Ilya V. Yevdokimov ◽  
Thomas H. DeLuca
Keyword(s):  
Organic Compounds ◽  
Plant Communities ◽  
In Situ Extraction

Poly(Dimethylsiloxane) Elastomers from Aqueous Emulsions: III. Effects of Blended Silica Fillers and γ-Radiation-Induced Crosslinking

1998 ◽  
Vol 71 (5) ◽  
pp. 941-948 ◽  
Author(s):  
D. W. McCarthy ◽  
J. E. Mark
Keyword(s):  
Colloidal Silica ◽  
Film Formation ◽  
Continuous Phase ◽  
Γ Radiation ◽  
Silica Fillers ◽  
Radiation Induced ◽  
Different Shapes ◽  
Morphological Differences ◽  
Silica Phases

Abstract The morphologies of the reinforced elastomers prepared from emulsions were found to depend greatly on how the silica phases were introduced. More specifically, blending colloidal silica into the elastomer prior to film formation was found to yield a highly unusual elastomer in which the continuous phase was the silica and the dispersed phase the elastomer. This is the opposite of the usual case in which, for example, the silica is generated in-situ within the continuous elastomeric phase. These morphological differences were used to explain the different shapes of the stress—strain isotherms of these materials in simple elongation. Results on the crosslinking effects of gamma radiation demonstrated that this treatment represents another useful technique for optimizing the properties of these emulsion-derived materials.

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