Morfološko variranje, fenotipska plastičnost i fluktuirajuća asimetrija oblika cvetnih organa kod Iris pumila L.

Abstract

Analize unutar - i među - individualnihih razlika morfoloških struktura omogućuju otkrivanje obrazaca fenotipskog variranja, kao i ekološko - evolucionih mehanizama koji dovode do njihove divergencije. U ovoj disertaciji utvrđene su komponente fenotipske varijanse oblika funkcionalno različitih cvetnih organa kod entomofilne biljne vrste Iris pumila L., polimorfne u odnosu na boju cveta. Eksperimenti su vršeni na biljkama gajenim u eksperimentalnoj bašti, poreklom iz recipročnih ukrštanja 24 klonalna genotipa. Metodama geometrijske morfometrije utvrđeni su obrasci variranja oblika tri bilateralno simetrična organa: fola, standarda i grane tučka. Kod sva tri organa udeo simetrične komponente u ukupnom variranju oblika bio je najveći, dok je fluktuirajuća asimetrija (FA) dominirala u asimetričnoj komponenti. Iako se smatra da je primarni uzrok FA nestabilnost razvića, naša istraživanja su pokazala da fenotipska plastičnost može takođe da proizvede FA. Naime, replike cvetnih organa sa različitom orijentacijom prema suncu imale su različite vrednosti asimetričnih komponenti varijanse oblika, kao rezultat plastičnosti u odnosu na mikrosredinsku heterogenost ambijentalne svetlosti. Da veličina, oblik i boja cveta predstavljaju vizuelne signale za privlačenje potencijalnih oprašivača potvrdila su poređenja veličine cvetnih organa oprašenih i neoprašenih biljaka. Oprašeni cvetovi su, po pravilu, imali veće organe od neoprašenih, sa izuzetkom grane tučka. Regresione analize su pokazale da je veličina fola bila pod delovanjem pozitivne, a grane tučka negativne direkcione selekcije. Suprotno tome, oblik cvetnih organa se razlikovao u zavisnosti od boje, što ukazuje da je preferencija oprašivača prema specifičnim kombinacijama vizuelnih signala bila važan mehanizam morfološke divergencije reproduktivnih organa I. pumila.

Analyzes of intra - and inter - individual differences of morphological structures allow the detection of patterns of phenotypic variation, as well as ecological evolutionary mechanisms leading to their divergence. In this dissertation, components of the phenotypic variation of the shape of functionally distinctive flower organs were determined in the entomophilous plant, specific for striking flower color polymorphism, Iris pumila L. Experiments were carried out on plants grown in experimental garden, originating from reciprocal crossing of 24 clonal genotypes. Using the methods of geometric morphometrics patterns of variation of the shape of three bilaterally symmetrical organs (falls, standards and style branches) have been revealed. In all three floral organs, the proportion of the symmetric component in the overall shape variation was the highest, while the fluctuating asymmetry (FA) was dominated in asymmetric component. Although it is thought that primary cause of FA is developmental instability, our research has shown that phenotypic plasticity can also produce FA. Namely, replicas of flower organs with different orientations towards the sun had different values of asymmetric components of variance of the shape, as an outcome of plasticity in relation to the microenvironmental heterogeneity of ambient light. In this dissertation it is confirmed that size, shape and color of flowers are visual attractants for pollinators. Pairwase comparisons in size between pollinated and unpollinated flowers revealed that pollinated falls and standards are bigger related to their unpollinated pairs. Regression analyzes have shown that the size of the falls was under positive selection, while size of style branches was under negative direct selection. In contrast, the shape of the flower organs differed depending on their color, indicating that the pollinator's preference for specific combinations of visual signals was an important mechanism of morphological divergence of the reproductive organs of I. pumila.