Human-mediated climate change is one of the largest threats to the persistence of marine organisms in the near future. Research efforts in the Bernal lab aim to understand the phenotypic and molecular responses of tropical and subtropical marine species to global change, especially warming. Despite multiple decades of studies there are still pending questions associated with the effects of temperature.

Recently, the Bernal Lab was part of a large collaboration to understand how natural populations respond the effects of heatwaves in the Great Barrier Reef (Bernal*, Schunter*, et al. 2020. Science Advances). This work indicated that not all species respond the same way to acute warming, and that there are some core responses that are shared between species. The timing of the collections allowed identifying molecular differences between early stages of warming, and the middle of the heatwave, highlighting the fluctuations that take place throughout the warming event.

Currently we are developing projects aimed at understanding how different populations of broadly distributed species respond to global change. Local adaptation can modulate the response of marine fishes to environmental stressors, and we are evaluating these associations with a combination of population genomics and aquarium experiments.

Studies suggest that acclimation to temperature stress is possible for some species when individuals are exposed to warm waters at an early age (developmental plasticity) and/or when parents were also exposed to such conditions (transgenerational plasticity). This is observed in tropical damselfishes (Spiny chromis, A. polyacanthus), and in a recent study it was possible to confirm that compensation to warming is possible even when there is "step-wise" warming between generations. However, metabolic compensation and patterns of gene expression are different when compared to fish exposed to the same elevated temperatures for two generations (Bernal, et al. Molecular Ecology, 2018). Another study associated with acclimation suggests that both the rearing conditions of the parents as well as the temperature at the time of reproduction truly influence the metabolic compensation observed in transgenerational studies (Bernal, et al. Submitted). Overall, these studies suggest that the capacity for metabolic compensation via transgenerational plasticity in damselfishes depends on both the reproductive temperature of parents and the rate of warming across generations.

Currently, we are developing projects to understand the capacity and limitations of plasticity in species of the Gulf of Mexico and the Caribbean, through aquarium experiments.

To better understand the relationship between adaptation, acclimation and responses to global change, our research objectives will be completed with a combination of field collections (population genomics) and laboratory experiments (physiology and gene expression). For the latter, we have an aquarium facility of six independent recirculating saltwater systems, each equipped with two tanks of 100gals, precise temperature control and remote environmental parameters.

Marine ecosystems are characterized by an apparent paucity of physical barriers to account for reproductive isolation, and the potential for dispersal during larval stages allows for the maintenance of connectivity across distant biogeographic provinces. These two factors generate important questions of how speciation of marine species takes place. This is particular important for hyper-diverse ecosystems, such as coral reefs.

My PhD dissertation was focused on the evolutionary history of the genus Haemulon, a group where most sister species have completely overlapping distributions. Using massively parallel sequencing techniques, we detected mitochondrial introgression between sister species with sympatric distribution in the Tropical Eastern Pacific (Bernal, et al. Molecular Ecology, 2017). For three closely-related Caribbean species, we found strong divergent selection for genes associated to body shape and pharyngeal morphology, which is consistent with their stark differences in feeding morphologies reported in previous studies (Bernal, et al. PeerJ, 2019). These patterns are consistent with other studies of broadly distributed marine organisms, that suggest disruptive selection plays a key role in diversification in the absence of strong geographic barriers.

Root-fungi associations:

As a lab technician during my undergraduate, I had the opportunity to work for Edward Allen Herre and F. Andy Jones. The I was responsible for aimed to understand the associations of fungi and roots of tropical trees. Such associations are key for understanding nutrient cycling in tropical systems, considering the role of fungal symbionts in nitrogen fixation. One of the main achievements from the project was the successful identification of tree species using only their roots, with the application of chloroplast markers.

DNA Barcoding of Caribbean Reef Fishes:

As an undergraduate at Universidad de Panama, my thesis project was focused on DNA Barcoding of Marine fishes. I used DNA barcodes for a molecular characterization of coral reef fish fauna of the Bocas del Toro Archipelago, Panama. The research project was part of the Smithsonian Barcode of Life Initiative. The information from this project resulted in a significant increase in the number of reference sequences for Caribbean fish in the Barcoding for Life Database. This project was my first experience with genetic techniques, and also sparked my interest in speciation.