Linking Specialisation and Stability of Plant ... - OPUS Würzburg

5.5 discussion 97
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Bray−Curtis similarity of visited plants
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Mean Bray−Curtis similarity of random plant samples
Figure 5.4: Similarity of flower selection across sites. The Bray-Curtis similarity
of plant species visited by an insect species at two altitudes
is plotted against the mean similarity of random samples
of all flowering plants available to the insect at the two sites. The
dashed diagonal line marks the expected similarity of visited
plant species under the null hypothesis of random selection of
flowers. Filled circles indicate significantly higher similarity of
visited plants than expected by chance, as determined in randomization
tests. Open circles indicate nonsignificant tests. The
solid line is the prediction of a linear regression: sqrt(y) = 1.167
x + 0.336, p < 0.001, F 1,105 = 51.28, R²= 0.32.
5.5 discussion
In order to be able to predict the effects of climate change on
plant-pollinator interactions via shifts in phenology, it is important
to understand to what extent pollinator species depend
on phenological synchrony with specific plant species as floral
resources. The current study sheds light on this question
by considering the relationship between pollinator specialisation
and phenological synchrony with flowering plants along
an altitudinal gradient. Contrary to our expectation, we found
that specialised pollinators did not show a closer phenological
match with the plant species they visited than generalised pollinators.
Moreover, the similarity of plant species visited by the
same pollinator species at different altitudes (“visitation consistency”)
was highly variable within species and showed no