Jakub Těšitel Department of Botany

Faculty of ScienceUniversity 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

Early Intermediate Late

early reproduction

low reproductive potential

less effective but safe strategy

reproduction postponed

high reproductive potential

risky but highly effective strategy

Trade-offM. sylvaticum

Seasonal variation – introduction

Vegetative internode number= number of internodes above which are nodes that have potential to bear branchesthe 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

Number of stem internodes

Num

ber

of pla

nts

1

1 2 3 4 5 60

10

20

30

2

1 2 3 4 5 6

3

1 2 3 4 5 6

4

1 2 3 4 5 6

5

1 2 3 4 5 6

6

1 2 3 4 5 60

10

20

30

7

1 2 3 4 5 6

8

1 2 3 4 5 6

9

1 2 3 4 5 6

10

1 2 3 4 5 6

11

1 2 3 4 5 60

10

20

30

12

1 2 3 4 5 6

13

1 2 3 4 5 6

14

1 2 3 4 5 6

15

1 2 3 4 5 6

16

1 2 3 4 5 60

10

20

30

17

1 2 3 4 5 6

18

1 2 3 4 5 6

19

1 2 3 4 5 6

20

1 2 3 4 5 6

23

1 2 3 4 5 60

10

20

30

24

1 2 3 4 5 6

Vegetative internode number distribution in populations of M. sylvaticumBut 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 & pratenseM. pratenseM.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 ecotype Late ecotype Seasonal 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 meadows oak-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!