Jakub Těšitel Department of Botany Faculty of Science University of South Bohemia data collected by Jakub Těšitel and Milan Štech Ecological and Evolutionary Aspects of the Seasonal Variation in Melampyrum (Orobanchaceae)

Reproductive strategy in Melampyrum  hemiparasitism, strict annuality (even in communities where perennials prevail), NO vegetative reproduction  limited backup features (damage response)  very limited seed bank (if any)  large, heavy seeds  the main goal of the reproductive effort = to produce as many seeds as possible... is generally succesful – widespread species with broad niche Seasonal (= architectural) variation  affects plant architecture determines the phenology is fixed genetically (e. g. Zopfi 1993, 1998)  produces ecotypes which differ primarily in the number of the stem vegetative internodes consequently differ in reproductive potential (presence and number of lateral florescences) What we know EarlyIntermediateLate early reproduction low reproductive potential less effective but safe strategy reproduction postponed high reproductive potential risky but highly effective strategy Trade-off M. sylvaticum

Seasonal variation – introduction Vegetative internode number = number of internodes above which are nodes that have potential to bear branches  the key morphological trait determining the ecotypes  is likely to be directly determined genetically  affects other architetural traits number of flowering branches number of flowers etc. through which it affects reproductive potential and timing of flowering  is under strong selection pressure Vegetative internode number distribution in populations of M. sylvaticum But what is this for?

 reproductive strategies are pretty similar across individual species BUT  the patterns of the seasonal variation are fairly different Let’s look at individual species Mean vegetative internode number within a population

 continual character of the seasonal variation  the timing of flowering and reproduction depends on the altitude.  the altitudinal gradient affects the vegetative internode number as well. M. sylvaticum & pratense M. pratense M.sylvaticum

 the seasonal ecotypes are distinct (similar pattern can be found in Rhinanthus or Euphrasia species)  the morphology is independent of the altitudinal gradient  the early flowering ecotypes grow on MOWN meadows  late flowering populations are common in oak-hornbeam forests  mixed populations or transitional types are rare M. nemorosum

Early ecotypeLate ecotypeSeasonal varition M. sylvaticum alpine meadows at the tree-line montane spruce forest continuous M. pratense alpine meadows at the tree-line, montane heathlands and peatbogs oak forests on acid soil, spruce forests continuous M. nemorosum MOWN meadowsoak-hornbeam forests distinct ecotypes stress disturbance competition human impact Habitat preferences of ecotypes. Any general patern?

Conclusions  The main function of the seasonal variation seems to be the determination of the optimal resource-allocation strategy  The seasonal variation enables shifts along the stress (S), or disturbance tolerance (R) – competitiveness(C) axis and thus broadens the niche of species and promotes their evolutionary success  The human management could have caused the distinctness between the seasonal ecotypes in M. nemorosum (similar to Rhinanthus and Euphrasia species).

Thanks for your attention!