Temporal variation in the influence of forest succession on caterpillar communities: A long‐term study in a tropical dry forest

Changes in Coleopteran assemblages over a successional chronosequence in a Mexican tropical dry forest

Coleopterans are the most diverse animal group on Earth and constitute good indicators of environmental change. However, little information is available about Coleopteran communities' responses to disturbance and land-use change. Tropical dry forests have undergone especially extensive anthropogenic impacts in the past decades. This has led to mosaic landscapes consisting of areas of primary forest surrounded by pastures, agricultural fields and secondary forests, which negatively impacts many taxonomic groups. However, such impacts have not been assessed for most arthropod groups. In this work, we compared the abundance, richness and diversity of Coleopteran morphospecies in four different successional stages in a tropical dry forest in western Mexico, to answer the question: How do Coleopteran assemblages associate with vegetation change over the course of forest succession? In addition, we assessed the family composition and trophic guilds for the four successional stages. We found 971 Coleopterans belonging to 107 morphospecies distributed in 28 families. Coleopteran abundance and richness were greatest for pastures than for latter successional stages, and the most abundant family was Chrysomelidae, with 29% of the individuals. Herbivores were the most abundant guild, accounting for 57% of the individuals, followed by predators (22%) and saprophages (21%) beetles. Given the high diversity and richness found throughout the successional chronosequence of the studied tropical dry forest, in order to have the maximum number of species associated with tropical dry forests, large tracts of forest should be preserved so that successional dynamics are able to occur naturally.

Long-term spatiotemporal variation in density of a tropical folivore: responses to a complex disturbance regime

The Anthropocene is a time of unprecedented and accelerating rates of environmental change that includes press (e.g., climate change) and pulse disturbances (e.g., cyclonic storms, land use change) that interact to affect spatiotemporal dynamics in the density, distribution, and biodiversity of organisms. We leverage three decades of spatially explicit data on the density of a tropical folivore (Lamponius portoricensis [Insecta, Phasmida]) in a hurricane-mediated ecosystem (montane rainforest of Puerto Rico), along with associated environmental attributes, to disentangle the effects of interacting disturbances at multiple spatial scales. Spatiotemporal variation in density at a small spatial scale is affected by disturbance-related characteristics (hurricane severity, time after most recent major hurricane, ambient temperature, and understory temperature), legacies of previous land use, and understory habitat structure. Nonetheless, only a small proportion of spatiotemporal variation in density was related to those characteristics. In contrast, the majority of interannual variation in mean density at a larger scale was related to disturbance characteristics and understory habitat structure. These factors combine to affect a weak and declining trend in the density of L. portoricensis over time. The low resistance of L. portoricensis to Hurricane Hugo, as compared to Hurricanes Georges and Maria, likely arose because a drought followed Hurricane Hugo. The disturbance regime of the region is predicted to include increases in ambient temperatures, frequency of high-intensity storms, and frequency of droughts. Such trends may combine to threaten the conservation status of L. portoricensis, and other species with which it shares similar life history characteristics.

Observed Ecological Communities Are Formed by Species Combinations That Are among the Most Likely to Persist under Changing Environments

AbstractDespite the rich biodiversity found in nature, it is unclear to what extent some combinations of interacting species, while conceivable in a given place and time, may never be realized. Yet solving this problem is important for understanding the role of randomness and predictability in the assembly of ecological communities. Here we show that the specific combinations of interacting species that emerge from the ecological dynamics within regional species pools are not all equally likely to be seen; rather, they are among the most likely to persist under changing environments. First, we use niche-based competition matrices and Lotka-Volterra models to demonstrate that realized combinations of interacting species are more likely to persist under random parameter perturbations than the majority of potential combinations with the same number of species that could have been formed from the regional pool. We then corroborate our theoretical results using a 10-year observational study, recording 88 plant-herbivore communities across three different forest successional stages. By inferring and validating plant-mediated communities of competing herbivore species, we find that observed combinations of herbivores have an expected probability of species persistence higher than half of all potential combinations. Our findings open up the opportunity to establish a formal probabilistic and predictive understanding of the composition of ecological communities.

Information arms race explains plant-herbivore chemical communication in ecological communities

Plants emit an extraordinary diversity of chemicals that provide information about their identity and mediate their interactions with insects. However, most studies of this have focused on a few model species in controlled environments, limiting our capacity to understand plant-insect chemical communication in ecological communities. Here, by integrating information theory with ecological and evolutionary theories, we show that a stable information structure of plant volatile organic compounds (VOCs) can emerge from a conflicting information process between plants and herbivores. We corroborate this information "arms race" theory with field data recording plant-VOC associations and plant-herbivore interactions in a tropical dry forest. We reveal that plant VOC redundancy and herbivore specialization can be explained by a conflicting information transfer. Information-based communication approaches can increase our understanding of species interactions across trophic levels.