Abstract: Interactions between plants and insects have long fascinated scientists, as they share a strong bond. While some plants rely on insects for pollination and seed dispersal, some insects rely on plants for food or as places to breed. This tight relationship makes investigating the evolutionary links between these two groups essential to understand how their co-evolution has been shaped by numerous factors. By studying the ecological and evolutionary implications of their interactions, researchers can gain insights into the complex relationship between plants & insects.
In this work, we aimed to better understand this evolutionary history by investigating the relationship between plant and insect phylogenetic diversity (PD) with a focus on islands as we wanted to examine the influence of island parameters, namely, size, distance to the mainland (i.e., isolation), age, and latitude on such relationship.
We hypothesize that closely related plant communities (i.e., low PD) support closely related insect communities due to co-evolution and island remoteness, and therefore, plant communities with high PD host highly diverse insect communities. Moreover, we think that this relationship varies on the island area, isolation, and age.
Based on bibliographic reviews and the use of online databases, we were able to retrieve species lists from islands scattered all around the globe (n=82), and subsequently calculate PD (e.g., Mean Pairwise Distance and Mean Nearest Taxon Distance) for plants. In insects, we used the number of genera, families, and order as a proxy for PD.
Based on our preliminary results, we found that insect and plant PD are positively correlated. This mutual increase in PD indicates that insects and plants co-evolve on islands as closely related insects are associated with closely related plants. Furthermore, we found that the isolation is positively influencing plant PD whereas insect PD was not influenced by the isolation. This may be due to plants We also found that large islands support lower PD for both. We could not find significant effects of latitude nor island age, neither on insect nor on plant PD.
These findings have important implications for conservation efforts on islands, as they suggest that protecting plant species on small distant islands (i.e., high PD) may also help to conserve insects widely spread across phylogenetic tree, and vice versa. Finally, our work should provide new insights into the evolutionary relationships between plants and insects and the ecological roles that distinct species play within ecosystems on a community level on islands.
