@misc{Pijanowska_Joanna_Podłoże,_1980,
 author={Pijanowska, Joanna},
 editor={Polska Akademia Nauk. Komitet Ekologiczny},
 copyright={Creative Commons Attribution BY 3.0 PL license},
 address={Warszawa},
 howpublished={online},
 year={1980},
 language={pol},
 abstract={This is a review of concepts and hypotheses on morphological variability of planktonic organisms, since Lauterborn’s (1901) paper up to the most recent ones (1977—1978). Planktonic organisms are variable in size, shape and proportions of body, both in time and space. Phenomena of morphological variability are common among planktonic algae (mainly Bacillariophyceae and Dinophyceae), protozoans (Lobosa), rotifers (mainly Brachionidae) and crustaceans (Cladocera and to a lesser extent Copepoda). Apart from size and proportions of body the crustaceans vary in shape and height of head, length of I and II pair antennae, mucro and tail spine length, and as for algae, rotifers and crustaceans occurrence of all kinds of exuberances and spines (Fig. 2). Phenomena of morphological variability are basically controlled by three types of factors: (1) genetic factors decide about the potential ability to form various morphotypes, (2) environmental factors give an impulse for manifestation of a genetically conditioned character, whereas (3) selection keeps up this diversity. Seasonal morphological variability may be either due to plasticity of genotypes in relation to environmental changes, or phenotypic cycles may be caused by seasonal changes in relative frequencies of genetically differing clones. Spatial variability may be due to genetic differences among parthogenetic clones or to differences in abilities of one genotype to produce morphologically different phenotypes under varying conditions (Fig. 1). Thus potential abilities of individuals of one species to form different morphotypes are conditioned by factors of a genetic character, but the realization of these theoretical abilities depends on environmental factors. Among environmental factors which may cause morphological variability of planktonic organisms the most frequently mentioned are: temperature, water mixing, light, concentration and kind of food, presence of predators which by organic substances excreted into the environment may stimulate some morphological changes of their potential prey. It can not be said for sure which of these factors are directly responsible for this variability, which indirectly — by changes in their intensity imply changes of factors directly responsible for variability, and which inform only about the intensity of factors decisive for variability.},
 abstract={Variability, to put it more precisely, the genetic information responsible for it, would not be maintained by generations, if it would not have any or only slight functional significance. The possible significance of structural modifications allowing to exist at suitable water depths is discussed. All changes, based on an increase or reduction of some parts of the body in relation to others increase the resistance of the body, and they may counteract the rotational motion of organism, help to move horizontally and to face water currents. Morphological variability is also of undisputable importance for the reduction of mortality due to predation. Selection favours individuals (clones) which, because of a determined size, shape, colour or presence of specific structures, are more resistant to be caught by predatory invertebrates and vertebrates (Figs. 3 and 4). Selection, by favouring individuals of modified shape, could result after some time in the formation of a uniform population as regards a given genotype. But constant frequency of genes in a population (Fig. 5) can be maintained either by selection, changing its direction during the year, or by negative feedback, i.e. when at too high genotype frequency its chances for survival decrease, and it becomes unfavourable even under constant environmental conditions. Therefore in order to maintain constant frequency of genes in a population, a reverse correlation should take place between the frequency of a genotype and its adaptive value. Polymorphism of planktonic organisms is a result of maintaining the specific genetic constitution which allows them to function in a broad spectrum oi variability of environmental factors and allows many of them the common occurrence.},
 type={Text},
 title={Podłoże, przyczyny i znaczenie zmienności morfologicznej organizmów planktonowych},
 URL={http://www.rcin.org.pl/Content/189189/PDF/WA058_140718_P3259-26_Eko-Pol-B.pdf},
 volume={26},
 number={1},
 journal={Ekologia Polska. Seria B},
 journal={Wiadomości Ekologiczne},
 publisher={Państwowe Wydawnictwo Naukowe},
 keywords={plankton, morphology, variability, polymorphism (zoology)},
}