Fenotipska plastičnost ekofizioloških, morfoloških i fenoloških osobina Iris variegata L. (Iridaceae) i diferencijacija genotipova poreklom iz staništa sa različitim svetlosnim karakteristikama
Phenotypic plasticity of ecophysiological, morfological and phenological traits of Iris variegata L. (Iridaceae) and differentiation of genotypes originating from contrasting light habitats
Doctoral thesis (Published version)
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The main aims of this research were to study the effects of heterogeneous light conditions on the amount and pattern of phenotypic plasticity of morphological, ecophysiological and phenological traits as well as their influence on the reproductive potential in genotypes of Iris variegata growing in controlled experimental conditions. It has been shown in the previous research, that Iris variegata as well as the congeneric Iris pumila are good model systems for research in evolutionary studies of the plants. The natural habitats of Iris variegata, hungarian or yellow iris, are on the territory of Serbia in the north, east and south parts. This research included plants of Iris variegata from the protected natural reserve of the Deliblato Sands. We have selected genotypes which are in their natural habitats exposed to heterogeneous light conditions: open habitats where they are exposed to full sun light, and the shade habitats under a cover of green plants of different forest stands with less intensity and changeable light quality (vegetative shade). The parts of genotypes have been transplanted to the experimental garden with clearly defined light intensities and qualities. The experimental garden consisted of two light treatments: one with higher light intensity and higher red/far-red ratio and the other with lower intensity and lower red/far-red ratio. The experiment lasted two years, and the values of morphological and ecophysiological traits were measured three times during a year - in spring, summer and autumn. Flowering and fruiting output were recorded during the flowering time and fruit forming (May and June). The variability of researched traits of Iris variegata has been evaluated by the analysis of the variance of repeated measurements, and the mutual relation of traits by correlation analysis. Referring to the results of this research it was noted that morphological and ecophysiological leaf traits of Iris variegata show significant phenotypic plasticity caused by light intensity and quality change. The amount and direction of phenotypic change were specific for the trait as well as for the light treatment. During higher intensity conditions and red/far-red ratio there were higher values of stomatal density. Specific leaf area was larger under low intensity treatment and red/far-red ratio. The concentration of photosynthetic leaves pigments was higher in the part of light gradient with lower intensity and red/far-red ratio. The phenotype of Iris variegata has significantly changed during the vegetative seasons as well as during two experimental years, and the amount and direction of those changes were specific for individual traits. Significatly different patterns of variation between two experimental years were confirmed for all morphological and ecophysiological traits except for the concentration of carotenoids. Effects of different intensity and quality of light on flowering phenology and various reproductive traits were not detected. Absence of plasticity, genetic variability and genetic variability of phenotypic plasticity was uncovered for almost all phenological and reproductive traits. Flowering traits significantly varied between the experimental years, and the fruiting traits had relatively similar values in two years of the experiment. Significant differences between genotypes were found for a small number of flowering traits and for traits describing fruiting success. Significant differences in mean values were observed between genotypes from different habitat types in Iris variegata regarding number of flowers and seed mass per capsule. Plants originating from same habitat differed significantly in average duration of flowering time. Heritability estimates had a low range of variation and were -trait, treatment, year and seasonal specific. Heritability coeficients of flowering and fruiting traits were mainly with higher values comparing with morphological and ecophysiological traits of Iris variegata. Stomatal density had the highest individual values of heritability among morphological and ecophysiological traits. The correlations between ecophysiological traits were in almost all cases significant and positive. In spite of the differences in light environment and the plant origin, the correlational relations between flowering and fruiting traits were stable in both years of the experiment. Mantel’s test did not show significant difference of correlational matrix among the experimental years, treatments as well as the vegetative seasons. Comparing the results of research carried out at two congeneric species (I. variegata and I. pumila), it was noted that there are similar responses for some traits (morphological and ecophysiological), but also significant differences in some components of flowering and fruiting success. The experiment was conducted on a large number of genotypes of Iris variegata and points to the need of involving a number of factors in ecological and evolutionary research. Significatly different patterns of variation between two experimental years, as well as significant change in trait values during spring, summer and autumn, clearly show necessity of monitoring spatial as well as temporal environmental heterogeneity. Considering that genotypes of Iris variegata and Iris pumila display a significant variability in response to variation in the light conditions, indicate the importance of the comparative approach and the need of following different types of traits in future experiments.
Keywords:Heterogeneous light conditions; Phenotypic plasticity; Iris variegata; Variability of vegetative and reproductive traits; Repeated measures analyses,; Correlations.
Source:University of Belgrade, Faculty of Biology, 2017, 1-209
- Evolution in Heterogeneous Environments: Adaptation Mechanisms, Biomonitoring and Conservation of Biodiversity (RS-173025)