How Plastic Can Phenotypic Plasticity Be? The Branching Coral Stylophora pistillata as a Model System

Phenotypic plasticity enables multicellular organisms to adjust morphologies and various life history traits to variable environmental challenges. Here, we elucidate fixed and plastic architectural rules for colony astogeny in multiple types of colonial ramets, propagated by cutting from genets of the branching coral Stylophora pistillata from Eilat, the Red Sea. We examined 16 morphometric parameters on 136 one-year old S. pistillata colonies (of seven genotypes), originating from small fragments belonging, each, to one of three single-branch types (single tips, start-up, and advanced bifurcating tips) or to structural preparative manipulations (representing a single or two growth axes). Experiments were guided by the rationale that in colonial forms, complexity of evolving phenotypic plasticity can be associated with a degree of structural modularity, where shapes are approached by erecting iterative growth patterns at different levels of coral-colony organization. Analyses revealed plastic morphometric characters at branch level, and predetermined morphometric traits at colony level (only single trait exhibited plasticity under extreme manipulation state). Therefore, under the experimental manipulations of this study, phenotypic plasticity in S. pistillata appears to be related to branch level of organization, whereas colony traits are controlled by predetermined genetic architectural rules. Each level of organization undergoes its own mode of astogeny. However, depending on the original ramet structure, the spherical 3-D colonial architecture in this species is orchestrated and assembled by both developmental trajectories at the branch level, and traits at the colony level of organization. In nature, branching colonial forms are often subjected to harsh environmental conditions that cause fragmentation of colony into ramets of different sizes and structures. Developmental traits that are plastic, responding to fragment structure and are not predetermine in controlling astogeny, allow formation of species-specific architecture product through integrated but variable developmental routes. This adaptive plasticity or regeneration is an efficient mechanism by which isolated fragments of branching coral species cope with external environmental forces

Morphogenetic Polyvariance in the Colonial Hydroid Dynamena pumila (L.)

The formation of aberrant modules (internodes) of the shoot was found sporadically in the colonial hydroid Dynamena pumila from the family Sertulariidae, which is distinguished by the symmetrical two-row position of the hydrotheca on the shoot stem. Despite rare significant deviations from the norm in the structure of some modules, the following modules in the shoots are formed normally. All variants of deviation from the norm (called morphovariations) are classified and, in general, are represented by four groups according to the possible reasons for their occurrence. The morphotypes are the most interesting morphological variations and look like similar modules in other genera of hydroids. Considering the position of the aberrant modules on the shoots of one colony, we can confidently infer that they were formed at different times, which undermines the assumption that deviations from the norm in morphogenesis were caused by environmental factors. All morphovariations are characterized by certain occurrences. Consequently, the described phenomenon is not limited to phenotypic plasticity, polymorphism, or sequential changes of phenotypes in the life cycle and, therefore, is singled out as a special phenomenon called morphogenetic polyvariance

Hidden Morphotypes and Homologous Series in Phenotype Variations in the Colonial Hydroids <i>Dynamena pumila</i>, <i>Diphasia fallax</i>, and <i>Abietinaria abietina</i> (Hydrozoa, Leptothecata)

The intraorganismal variability of the shoot modules of three species of hydroids was studied to determine the degree of similarity between them. The strict form of the internodes (modules) of the shoots is repeated many times, which is useful for the study of intraorganismal variability. Against the general background of the high stability of the shape of the internodes, we found significant deviations from the norm. Some resemble the structure of the internodes in other genera of the same family. Their morphogenesis is different from that characteristic of the studied species. Most of the anomalies were characterized by stable forms and low frequencies of occurrence (Dynamena pumila, Diphasia fallax, and Abietinaria abietina, the composition of their morphovariations was found to be similar, and their frequencies were comparable, which confirms the assumption that several latent phenotypes can be formed indeterminately based on one genotype. The study was conducted on samples of >20,000 internodes of each of the three species

A PROFILE OF ONLINE COURSE STUDENT

This article presents the results of a two-year study of massive open online courses (MOOC) «Modern Environmental Problems and Sustainable Development», which is effective since September 2015 on National Russian Platform «Open Education» in terms of learners' audience. A learner's profile is made on the basis of the conducted survey. According to the data collected, these are young women, who are interested in this subject and who are currently students or young specialists residing mainly in Moscow region. We found out that 9-11% of the learners, who were initially enrolled, have completed the course. These figures are similar to the ones collected by foreign researchers on the basis of analysis of MOOCs run in other countries. One of the reasons for subscribing to an online course given was the opportunity to enlarge knowledge. This fact would be meaningful for improving existing courses so that they not only provide new information but revise existing knowledge as well. The important factor that describes a rise in popularity of online course «Modern Environmental Problems and Sustainable Development» is the increase in the number of subscribers who live abroad in 2016