No abstract

The pollination syndrome hypothesis predicts that plants pollinated by the same pollinator group bear convergent combinations of specific floral functional traits. Nevertheless, some studies have shown that these combinations predict pollinators with relatively low accuracy. This discrepancy may be caused by changes in the importance of specific floral traits for different pollinator groups and under different environmental conditions. To explore this, we studied pollination systems and floral traits along an elevational gradient on Mount Cameroon during wet and dry seasons. Using Random Forest (Machine Learning) models, allowing the ranking of traits by their relative importance, we demonstrated that some floral traits are more important than others for pollinators. However, the distribution and importance of traits vary under different environmental conditions. Our results imply the need to improve our trait‐based understanding of plant‐pollinator interactions to better inform the debate surrounding the pollination syndrome hypothesis.

The pollination syndrome hypothesis predicts that plants pollinated by the same pollinator group bear convergent combinations of specific floral traits. Nevertheless, some studies have shown relatively low predictive power for these floral trait combinations. This discrepancy may be caused by changes in the importance of specific floral traits for shaping interactions under different environmental conditions and for different pollinator groups. To test this, we studied pollination systems and floral traits along an elevational gradient on Mount Cameroon during wet and dry seasons. Using Random Forest models, allowing the ranking of traits by significance, we demonstrated that some floral traits are more important than others in shaping interactions and that these traits predict pollinators relatively well. However, the distribution and importance of traits varies under different environmental conditions. Our results imply the need to improve our trait-based understanding of plant-pollinator interactions to better inform the debate surrounding pollination syndrome hypothesis.

Adults and larvae of a true bug, Scantius aegyptius (Heteroptera: Pyrrhocoridae), closely resemble sympatric firebugs, Pyrrhocoris apterus, and probably form a mimetic relationship with the latter species. Scantius aegyptius adults, although producing a secretion atypical of true bugs, are to some extent chemically protected against predators. In this study, we analysed the composition and function of the larval secretion in S. aegyptius, and investigated the mimetic relationship between larvae of S. aegyptius and P. apterus. The main component of the larval secretion in S. aegyptius is 2-heptanol, a chemical not known to function in anti-predatory defence, followed by (E)-2-octenal, a common defensive chemical of true bugs. When larvae of both species were presented to jumping spiders (Evarcha arcuata), S. aegyptius was slightly less well protected than P. apterus, but the spiders behaved towards the two species in a similar way: they quickly learned to avoid the bugs, but usually attacked them again on the second day. The spiders also generalized their learned avoidance from one true bug species to the other (with only slight asymmetry favouring S. aegyptius), suggesting that the bugs’ mimetic relationship is most probably Müllerian, being advantageous to both species.