Signification adaptative des différents types de développements postembryonnaires chez les Gamasides (Acariens: Anactinotriches)

1987 ◽  
Vol 65 (6) ◽  
pp. 1299-1310 ◽  
Author(s):  
Françoise Athias-Binche
Keyword(s):  
Phenotypic Plasticity ◽  
Postembryonic Development ◽  
Adaptive Significance ◽  
Relative Duration ◽  
Developmental Patterns ◽  
Selection Strategies ◽  
Full Development ◽  
Gamasid Mites ◽  
Embryonic Ectoderm ◽  
Duration Of Development

This review of the adaptive significance of various patterns of postembryonic development in the gamasid mites is restricted to the phenotypic and adaptive aspects of the different developmental patterns. Postembryonic development is redefined as beginning with achievement of embryonic ectoderm differentiation into a sclerified recognizable integument. The various kinds of postembryonic development depend on the ecology of the species and their adaptative strategies, ranging from generalized edaphic forms to more specialized species, either colonizing unpredictable habitats or being parasitic. In relation to progressive specialization, the relative duration of development tends to decrease from four active instars to three or two instars, or even to an abbreviated adult–adult cycle in endoparasitic species. One can distinguish the following main features: full development with four active instars, full development but comprising one or several phoretic instars; abbreviated development, with regressed apomorphic larva, with ovolarviparity, with regressed protonymph or with both regressed protonymph and deutonymph associated with ovolarviparity, and occasionally with phoresy. Phenotypic plasticity may occur and can be marked by facultative, behavioural, or polymorphic phoresy, facultative ovolarviparity, occasional arrhenotoky, or appearance of dormancy. The adaptive fitness of these different characters is discussed in terms of r–K selection strategies, colonizing dynamics, and specialized microhabitats. The concepts of adaptative and evolutive processes are briefly discussed, including Grandjean's theory of "l'évolution selon l'âge."

scholarly journals Climate change, biosystematics and taxonomy

2021 ◽  
Vol 28 (1) ◽  
pp. 277-287
Author(s):  
M Khairul Alam
Keyword(s):  
Climate Change ◽  
Phenotypic Plasticity ◽  
Environmental Conditions ◽  
Information Needs ◽  
Adaptive Significance ◽  
High Incidence ◽  
Plant Taxon ◽  
History Of ◽  
Impacts Of Climate Change

The history of biosystematics research and its impacts on climate goes before political ramifications. Climate change is altering the environments and likely to result in changes in the distribution of species, flowering times; migrate and adapt to the new environmental conditions; or extinction. Adaptive capacity is the ability of the plants to adapt to the impacts of climate change. Adaptation process is going in nature through phenotypic plasticity, natural selection or migration or polyploidization. The options are not mutually exclusive. Phenotypic plasticity may be the most efficient way of adaptation to a new environment. Polyploidization may increase tolerance to diverse ecological conditions and the high incidence of polyploidy in plants indicates its adaptive significance. Population having polyploid pillar complex is a good backup support towards microevolution and speciation, a mode of adaptation. The paper discusses about these biosystematics approaches towards adaptation to new environmental conditions resulting from climate change. It also discusses about the role of taxonomists under the changed circumstances. It is evident from the review that a set of biosystematics data along with other ecological and conservation information needs to be included in Flora and Monographs. It reveals that it was as far as worked out at the Paris Botanical Congress 1954 and put up by Stebbins in a series of proposals, termed as “Stebbins’ Ten Points” that needs further enrichment. Bangladesh J. Plant Taxon. 28(1): 277-287, 2021 (June)

Neuron-glia relationship during the early postembryonic development of the nervous system in some oligochaetes

1978 ◽  
Vol 36 (2) ◽  
pp. 600-601
Author(s):  
Wiktor Djaczenko ◽  
Carmen Calenda Cimmino
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Early Period ◽  
Postembryonic Development ◽  
Ruthenium Red ◽  
The Body ◽  
Tubifex Tubifex ◽  
Growth Stages ◽  
Cell Processes ◽  
Cytoplasmic Processes

The simplicity of the developing nervous system of oligochaetes makes of it an excellent model for the study of the relationships between glia and neurons. In the present communication we describe the relationships between glia and neurons in the early periods of post-embryonic development in some species of oligochaetes.Tubifex tubifex (Mull. ) and Octolasium complanatum (Dugès) specimens starting from 0. 3 mm of body length were collected from laboratory cultures divided into three groups each group fixed separately by one of the following methods: (a) 4% glutaraldehyde and 1% acrolein fixation followed by osmium tetroxide, (b) TAPO technique, (c) ruthenium red method.Our observations concern the early period of the postembryonic development of the nervous system in oligochaetes. During this period neurons occupy fixed positions in the body the only observable change being the increase in volume of their perikaryons. Perikaryons of glial cells were located at some distance from neurons. Long cytoplasmic processes of glial cells tended to approach the neurons. The superimposed contours of glial cell processes designed from electron micrographs, taken at the same magnification, typical for five successive growth stages of the nervous system of Octolasium complanatum are shown in Fig. 1. Neuron is designed symbolically to facilitate the understanding of the kinetics of the growth process.

Do Children With Developmental Language Disorder (DLD) Have Difficulties With Interference Control, Visuospatial Working Memory, and Selective Attention? Developmental Patterns and the Role of Severity and Persistence of DLD

2020 ◽  
Vol 63 (9) ◽  
pp. 3036-3050
Author(s):  
Elma Blom ◽  
Tessel Boerma
Keyword(s):  
Working Memory ◽  
Selective Attention ◽  
Language Disorder ◽  
Typically Developing ◽  
Developmental Language Disorder ◽  
Visuospatial Working Memory ◽  
Interference Control ◽  
Developmental Patterns ◽  
Search Tasks ◽  
The Impact

Purpose Many children with developmental language disorder (DLD) have weaknesses in executive functioning (EF), specifically in tasks testing interference control and working memory. It is unknown how EF develops in children with DLD, if EF abilities are related to DLD severity and persistence, and if EF weaknesses expand to selective attention. This study aimed to address these gaps. Method Data from 78 children with DLD and 39 typically developing (TD) children were collected at three times with 1-year intervals. At Time 1, the children were 5 or 6 years old. Flanker, Dot Matrix, and Sky Search tasks tested interference control, visuospatial working memory, and selective attention, respectively. DLD severity was based on children's language ability. DLD persistence was based on stability of the DLD diagnosis. Results Performance on all tasks improved in both groups. TD children outperformed children with DLD on interference control. No differences were found for visuospatial working memory and selective attention. An interference control gap between the DLD and TD groups emerged between Time 1 and Time 2. Severity and persistence of DLD were related to interference control and working memory; the impact on working memory was stronger. Selective attention was unrelated to DLD severity and persistence. Conclusions Age and DLD severity and persistence determine whether or not children with DLD show EF weaknesses. Interference control is most clearly impaired in children with DLD who are 6 years and older. Visuospatial working memory is impaired in children with severe and persistent DLD. Selective attention is spared.

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