Animal dispersal is a topic of increasing interest in macroecology. In insects, the Monarch migration is one of the most widely known dispersal events. In contrast, the dispersal of other species, like the diurnal Urania moths has been rather neglected. The larvae of Urania species feed only on plants of the genus Omphalea. These plants increase their toxicity as defense against herbivory, forcing the moths to move to different host-plant populations. The dispersal patterns of these moths have been mostly documented by observation, and the only study aiming to understand these patterns has been done for U. boisduvalii in Cuba, in which movement routes were modeled based on environmental connectivity and host-plant availability. Here, we combine biotic interactions, environmental suitability, and dispersal simulations to understand dispersal dynamics in the area of distribution of U. boisduvalii. Our approach differs in that it considers changes in suitability of patches with plants deriving from foraging. We hypothesize that this response can drive the “migration” patterns of U. boisduvalii in Cuba. We used a cellular automaton approach where the suitability of each cell is determined by climate, dispersal, presence of suitable food-plants, and its change due to herbivory. All analyses are implemented in R.
Results/Conclusions
Our results show that dispersal ability is crucial to identify suitable areas occupied by the species. Depending on this ability, various clusters of connected suitable areas were identified (patches of plants with suitable conditions for the moth that can be reached considering dispersal distance limits). With maximum dispersal ability of 10 km, three large isolated patches of suitable areas for the moth are recognized in the main island, suggesting three different metapopulations. With dispersal up to 30 km, all suitable patches become linked in the main island. We are working on simulating the dynamics with plant-patch quality driven by herbivory. We predict that dispersal patterns like the ones observed in other migrations events, will derive from changes in the suitability of plant patches (i.e., increase and decrease of toxicity) caused by the moth herbivory. Depending on dispersal ability, these movements will not necessarily occur over the entire island. This will be in clear contrast with the climate driven migration of the Monarch butterfly, and could be tested via population genetics analyses, which we are in the process of performing.