Propositions
Just for fun: the propositions of my thesis! They had to be formulated in a way that provokes discussions during the defence. Defending propositions is an old tradition at Leiden University.
Propositions
belonging to the PhD thesis
The structure of flower visitation webs:
How morphology and abundance affect interaction patterns between flowers
and flower visitors
Martina Stang
1. The structure of flower visitation webs is determined by size constraints
as well as
random interactions proportional to abundance (this thesis, contra Santamaría &
Rodrígres-Gironés 2007).
2. Asymmetric interactions (i.e. generalists interact mainly with specialists and vice versa) are primarily a result of the nectar depth threshold. Abundance modifies only how many of the potential interactions are actually realized (this thesis, CHAPTER 3, contra Vázquez 2005).
3. Although asymmetric interactions enhance the stability of a community, specialists still have higher extinction risks than generalists (this thesis, CHAPTER 3, contra Ashworth et al. 2004).
4. The average degree of morphological matching between nectar depth and proboscis length is mainly an effect of size thresholds and size distributions, and not of preferences and competition (this thesis, CHAPTER 4).
5. Flowers should adapt to flower visitors that roughly match their size not because they are a priory more effective but because they are more frequent.
6. That species are functional equivalent does not necessarily mean that they are redundant. Species may replace each other qualitatively but not quantitatively.
7. The term ‘central core’ used for generalist–generalist interactions in flower visitation webs is misleading (contra Bascompte et al. 2003).
8. Whether interaction patterns between flowers and flower visitors are a result of simple or complex rules is a matter of scale.
9. Like photographs, scientific models are interpretations of reality.
10. Although pollination is a gratis ecosystem service to society, disruption of plant– pollinator interactions can be costly.
11. Some ecologists get lost in the matrix and some others in the field.
12. One can learn to solve almost any problem (in memory of my father).