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For the study of pollination biology a
wide range of techniques are needed. Often you start with an "easy
question" and during your study you find out that you have more
questions than in the beginnig and that you need additional techniques.
Here are some of the methods we use in our lab.
| A. Reproductive
Biology, Pollination
Biology, and Breeding System |
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| Pollinator observations in field |
| Characterisation of the breeding system
via pollen-ovule ratios (p/o). Pollen
grains are counted with a Cellcounter and Analyser SYstem CASYTM (Schärfe
System GmbH, Germany) that additionally allows the determination of the pollen grain
diameter and volume.
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| Bagging experiments
to test for autogamy/geitonogamy/selfing ability |
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| Our espresso machine -
the Casy (Cell Analyser System) for pollen counting |
Result of a 10 second
"espresso" run: pollen grain number and size. In this
example two pollen grain peaks. |
| B. Ecology and Evolution of Floral
Morphology |
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| Functional aspects of
the flower
morphology in Caryophylloideae: adaptation to different pollination
modes.
Canonical
discriminant analysis (CDA) is
used to evaluate the hypothesis that diurnal, nocturnal, and
self-pollinating species in Caryophylloideae represent three
morphologically distinct groups, and to identify the characters
that are useful for their differentiation. Furthermore,
CDA
is used to evaluate the characters for the differentiation of
taxonomical groups.
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| Flower structure of Silene
vulgaris : (1A) calyx length; (1B) calyx tooth length; (1C)
calyx tooth width at base; (1D) calyx width, 25% from base of
calyx; (1E) calyx width, 50% from flower base of calyx, (1F) calyx
width, 75% from flower base of calyx;
Flower with part of calyx removed: (2A) anthophore length;
(2B) anthophore width; (2C) ovary length; (2D) ovary width, 25%
from base of ovary; (2E) ovary width, 50% from base of ovary; (2F)
ovary width, 75% from base of ovary; (3A) style length; (3B) style
width at the tip; (3C) style width, 25% from the tip; (3D) style
width, 50% from tip of style; (3E) style width at the base, (4A)
petal length from base to claw, (4B) plate width at the widest
point, (4C) plate length; (5A) length of outer filament, (5B)
length of inner filament, (5C) length of inner anther, (5D) length
of outer anther. |
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| C. SEM of floral parts
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| Are
anthophore features (length, hairyness etc.)
related with the pollination biology or taxonomy ?
In most Caryophylloideae the calyx
tube is correlated with the presence of an anthophore, an
elongated internode between sepals and petals, stamens, and ovary.
Nectar is normally secreted at the base of the ten filaments in
the depth of the calyx tube. In species with a long anthophore the
places of nectar secretion and nectar deposition are not the same.
The nectar gland is situated at the base of the filaments. If a
stipe is present nectar is secreted into 10 crypts which starting
from the gaps between the free filament bases conduct the nectar
down the stipe towards the base of the calyx tube. If the stipe is
lacking or very short the nectar collects directly at the bottom
of the calyx, there it is accessible for nectar-seeking flower
visitors. The secretion of nectar at the base of the filaments
makes it possible for nectar-seeking insects to find nectar not
only at the base of the flower but also in a shorter distance from
the flower entrance along the anthophore.
Therefore, in species with
anthophore nectar is accessible to a wider range of flower
visitors and even insects with shorter tongues may reach some
nectar when they push their head or body more deeply into the
flower tube. Thus, it can be assumed that species with a long
anthophore instead of a long ovary and/or style follow a mixed
strategy offering nectar to a wider range of flower visitors.
Nevertheless, nectar is accumulated at the base of the flower and
if present flower visitors with a long tongue will probably gain
the main supply.
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| Anthophore
of S. nicaeensis |
Anthophore
of S.
saxifraga |
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| Anthophore
of S. portensis |
Anthophore
of S.
zawadzkii |
| D. Nectar
dynamics and nectar composition |
| Nectar
dynamics: nectar secretion during day and night |
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| Mean
nectar volumes in protected male Silene
latifolia
flowers of different ages (303 flowers from 15 individuals).
From Witt et al.
(1999). Nectar
dynamics and sugar composition in flowers of Silene and Saponaria
species (Caryophyllaceae). - Plant Biology 3: 334-345. |
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| Nectar composition: is it related to
taxonomy or pollination biology ? |
| Nectar composition
(amino acids and sugars) of flowers are investigated via HPLC
(high performance liquid chromatography) in cooperation with
Gerhard Gottsberger, Hans Malchus, University of Ulm, Germany. |
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| Absolute and
relative nectar sugar contents [µg/µl] from Saponaria
officinalis flowers and different Silene flowers (different
sexual phenotype). h = hermaphrodite, f = female, m = male |
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| Places
of nectar secretion |
| Methods used
to analyse nectar composition via HPLC |
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| E. Ecology and
Evolution of Floral Odours |
| Floral odor composition:
is it related
to the pollination biology and/or the phylogeny of the species ? |
| Analysis of
floral odors - GC-MS (Gaschromatographie-massspectrometry),
GC-MS/MS, GC/MS MRM (multi reaction monitoring), GC-EAD and GC-MS-EAD
(In cooperation with Stefan Schütz, and Bernhard Weisbecker, Göttingen, Germany) |
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| Varian
Saturn 2000 GC-MS/MS System (left), and Varian Chromatoprobe
device (right) |
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| GC-MS
method for the analysis of floral odors of MicroSPE |
| GC-MS
method for the analysis of pollen odors |
| Statistical
analysis |
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| What are
the attractive compounds for flower visitors? |
| Windtunnel
Bioassays - We distinghuish between (1) orientation flight, (2)
landing at the odor source, and (3) proboscis extension. |
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| Description
of windtunnel methods |
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