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

Nikolay N Marfenin

doi:10.3390/d13120683

Abstract

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.

Highlights

In one organism, a colony in hydroids [1], along with the normal forms of shoot structure, various deviations from the norm can sometimes be found
Morphogenetic polyvariance is the ability of an organism to produce some alternative phenotypes besides the normal
Among the whole set of modular organisms, only in one species, D. pumila, the phenomenon of morphogenetic polyvariance has been studied in sufficient detail

Summary

Introduction

A colony in hydroids [1], along with the normal forms of shoot structure, various deviations from the norm can sometimes be found. They are of great interest when studying the mechanisms of morphogenesis. Among the whole set of modular organisms, only in one species, D. pumila, the phenomenon of morphogenetic polyvariance has been studied in sufficient detail. (a) How diverse are morphological aberrations? (b) Are they deformities? (c) Is there a limit to deviations from the norm of the structure? (d) Are there any regular differences between morphovariations in terms of their frequency of occurrence? (e) How often do morphological aberrations appear in the colony?

Characteristics of the Studied Species

Collection of Material

Findings

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