The confusing, the cryptic, and the unseen: phenotypic adaptation and functional diversity of morphologically challenging macroalgae

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Ecosystem function and resilience are generally correlated with species richness and diversity. However, the positive correlation between taxonomic and functional diversity largely depends upon our ability to differentiate species. Studies that avoid species distinctions and instead generalize with functional groups to make predictions about ecological processes are over-simplified and assumption-laden, as exceptions to species generalities are common. Our understanding of ecosystem function and the consequences of biodiversity loss therefore depends upon our ability to discriminate species and characterize their function. *** My research proposal focuses specifically on the problems caused by the misidentification of macroalgal species and the revolutionary ecological insight that can be had by species clarification. I categorize morphologically challenging macroalgae into three categories: single species exhibiting many phenotypes (i.e., “confusing”), many species exhibiting a single phenotype (i.e., “cryptic”), and species that have microscopic, often overlooked, life stages (i.e., “unseen”). These categories represent three distinct but related research directions that my lab will follow in the next five years:***-- Morphologically “confusing” species may artificially inflate estimates of biodiversity. We will use a combination of field transplants and controlled growth experiments in the lab to characterize the interactive effects of environmental factors on morphological plasticity. We will investigate the underlying mechanism of plasticity in kelps, which appear to share developmental similarities with land plants despite wide differences in evolutionary history. ***-- Morphologically “cryptic” species may yield underestimates of taxonomic and functional diversity. We will use DNA sequencing to identify crustose coralline algal species in kelp forests and urchin barrens, and then conduct a series of experiments to differentiate the physiological and functional diversity of these cryptic species. We will document the ability of each species to stimulate invertebrate and kelp recruitment and to resist environmental stress. Understanding these cryptic species will lend insight into kelp forest functioning and recovery from disturbance.***-- Some species have microscopic “unseen” life stages that may be critical to the persistence and stability of economically valuable macroalgal populations, but these stages are difficult to locate in the field and rarely studied in the lab. We will quantify the distribution of microscopic stages across marine landscapes by DNA sequencing. In the lab, we will culture microscopic stages and characterize their resistance to environmental stress and herbivory. These data will inform population models to make predictions about the persistence of macroalgal populations and harvestable yields in the future.