Phenotypic plasticity within and among populations of Scorzonera austriaca

Namen našega raziskovalnega dela je bil raziskati in pojasniti fenotipsko plastičnost avstrijskega gadnjaka Scorzonera austriaca znotraj populacij na Nanosu in dveh disjunktnih manjših populacijah izven jedra razširjenosti, na Boču in v bližini avstrijskega Gradca. Fenotipsko plastičnost testnih rastlin smo raziskovali na podlagi meritev morfološko-funkcionalnih potez in ekofizioloških meritev, ki so obsegale meritve fotokemične učinkovitosti rastlin – fluorescenco klorofila in vsebnost klorofila v listih ter meritve reproduktivnih znakov. Preko teh parametrov smo spremljali, ali sta izolirani populaciji zaradi fragmentiranosti habitata podvrženi genetskemu zdrsu in inbreedingu ter ali se izoliranost populacije in manj ogodne okoljske razmere (višja nadmorska višina) odražajo na fenotipski plastičnosti. Merjeni parametri so pokazali, da variabilnost fenotipske plastičnosti osebkov vzorčne populacije na Nanosu upada premosorazmerno z višanjem nadmorske višine. Fenotipska plastičnost vegetativnih delov na višjih nadmorskih višinah je v centru uspevanja manjša zaradi okoljskega stresa (ostrejši, za rastlino manj ugodni abiotski dejavniki). Prav tako smo znake zmanjšane fenotipske plastičnosti zasledili pri populaciji na Boču, ki je najverjetneje posledica fragmentacije habitata oziroma populacije. Visoko fenotipsko plastičnosti pa smo v nasprotju s pričakovanji zasledili pri izolirani populaciji avstrijskega Gradca, kar govori, da so rastline kljub izolirani populaciji še vedno verjetno dovolj genetsko variabilne. Z meritvami fluorescence klorofila smo zasledili zmanjšane vrednosti splošne učinkovitosti rastlin ter nižje vrednosti zelenega barvila pri vzorčnih populacijah Nanosa na višji nadmorski višini in disjunkcijah pri populaciji na Boču. Rezultati so za rastline z Boča in z višjih nadmorskih višin na Nanosu pokazali značilno nižje število cvetočih osebkov in manjše število semen. Za njih je torej značilno, da izkazujejo nižji fitnes in s tem nižji reproduktivni uspeh.The objective of the thesis was to research and explain the phenotipic plasticity of Scorzonera austriaca within the population on Mt. Nanos and two smaller disjunct populations, out of the core area of expansion, on Mt. Boč and near Graz (Austria). The phenotipic plasticity of test plants was researched by measuring morphological-functional parameters and by taking ecophysiological measurements, which included measuring photochemical efficiency of plants - chlorophyll fluorescence and chlorophyll content in the leaves, and measuring reproductive signs. We monitored, whether two isolated populations are subject to genetic slippage or inbreeding due to habitat fragmentation, and if the phenotipic plasticity is reflected as a consequence of unfavourable environmental factors in Mt. Nanos population. Measured parameters showed that the variability of phenotipic plasticity in tested population subjects on Mt. Nanos, is decreasing proportionally as altitude increases. The phenotipic plasticity of vegetative parts at higher altitude is smaller in the center of the thrift due to environmental stress (sharper, less favourable abiotic conditions for a plant). Signs of reduced phenotipic plasticity were found in the population of Mt. Boč as well, which is probably the consequences of habitat fragmentation or population fragmentation. Contrary to our expectations, a large amount of phenotipic plasticity has been found in the isolated population in Graz (Austria), which means plants are still genetically variable despite possible inbreeding, and there are no environmental stress factors noticed. Chlorophyll fluorescence measurements of S. austriaca showed reduced values of general plant efficiency and lower values of chlorophyll in test population at higher altitude of Nanos and disjunct in population of Mt. Boč. The results showed characteristically smaller numbers of blossoming subjects and fewer seeds for S. austriaca population on Mt. Boč and population at higher altitude of Nanos. They characteristically show lower fitness and therefore lower reproductive success