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1. Sponge–Microbe Interactions on Coral Reefs: Multiple Evolutionary Solutions to a Complex Environment

   https://doi.org/doi.org/10.3389/fmars.2021.705053  

   Freeman, CJ ; Easson, CG ; Fiore, CL ; Thacker RW ( July 2021 , Frontiers in marine science)

   Aldo Cróquer (Ed.)

   Marine sponges have been successful in their expansion across diverse ecological niches around the globe. Pioneering work attributed this success to both a well-developed aquiferous system that allowed for efficient filter feeding on suspended organic matter and the presence of microbial symbionts that can supplement host heterotrophic feeding with photosynthate or dissolved organic carbon. We now know that sponge-microbe interactions are host-specific, highly nuanced, and provide diverse nutritional benefits to the host sponge. Despite these advances in the field, many current hypotheses pertaining to the evolution of these interactions are overly generalized; these over-simplifications limit our understanding of the evolutionary processes shaping these symbioses and how they contribute to the ecological success of sponges on modern coral reefs. To highlight the current state of knowledge in this field, we start with seminal papers and review how contemporary work using higher resolution techniques has both complemented and challenged their early hypotheses. We outline different schools of thought by discussing evidence of symbiont contribution to both host ecological divergence and convergence, nutritional specificity and plasticity, and allopatric and sympatric speciation. Based on this synthesis, we conclude that the evolutionary pressures shaping these interactions are complex, with influences from both external (nutrient limitation and competition) and internal (fitness trade-offs and evolutionary constraints) factors. We outline recent controversies pertaining to these evolutionary pressures and place our current understanding of these interactions into a broader ecological and evolutionary framework. Finally, we propose areas for future research that we believe will lead to important new developments in the field. 

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2. Chemical Ecology of Marine Sponges: New Opportunities through “-Omics”

   https://doi.org/10.1093/icb/icz014  

   Paul, Valerie J ; Freeman, Christopher J ; Agarwal, Vinayak ( April 2019 , Integrative and Comparative Biology)

   Abstract The chemical ecology and chemical defenses of sponges have been investigated for decades; consequently, sponges are among the best understood marine organisms in terms of their chemical ecology, from the level of molecules to ecosystems. Thousands of natural products have been isolated and characterized from sponges, and although relatively few of these compounds have been studied for their ecological functions, some are known to serve as chemical defenses against predators, microorganisms, fouling organisms, and other competitors. Sponges are hosts to an exceptional diversity of microorganisms, with almost 40 microbial phyla found in these associations to date. Microbial community composition and abundance are highly variable across host taxa, with a continuum from diverse assemblages of many microbial taxa to those that are dominated by a single microbial group. Microbial communities expand the nutritional repertoire of their hosts by providing access to inorganic and dissolved sources of nutrients. Not only does this continuum of microorganism–sponge associations lead to divergent nutritional characteristics in sponges, these associated microorganisms and symbionts have long been suspected, and are now known, to biosynthesize some of the natural products found in sponges. Modern “omics” tools provide ways to study these sponge–microbe associations that would have been difficult even a decade ago. Metabolomics facilitate comparisons of sponge compounds produced within and among taxa, and metagenomics and metatranscriptomics provide tools to understand the biology of host–microbe associations and the biosynthesis of ecologically relevant natural products. These combinations of ecological, microbiological, metabolomic and genomics tools, and techniques provide unprecedented opportunities to advance sponge biology and chemical ecology across many marine ecosystems. 

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3. Comprehensive phylogenomic analyses re-write the evolution of parasitism within cynipoid wasps

   https://doi.org/10.1186/s12862-020-01716-2  

   Blaimer, Bonnie B. ; Gotzek, Dietrich ; Brady, Seán G. ; Buffington, Matthew L. ( December 2020 , BMC Evolutionary Biology)

   null (Ed.)

   Abstract Background Parasitoidism, a specialized life strategy in which a parasite eventually kills its host, is frequently found within the insect order Hymenoptera (wasps, ants and bees). A parasitoid lifestyle is one of two dominant life strategies within the hymenopteran superfamily Cynipoidea, with the other being an unusual plant-feeding behavior known as galling. Less commonly, cynipoid wasps exhibit inquilinism, a strategy where some species have adapted to usurp other species’ galls instead of inducing their own. Using a phylogenomic data set of ultraconserved elements from nearly all lineages of Cynipoidea, we here generate a robust phylogenetic framework and timescale to understand cynipoid systematics and the evolution of these life histories. Results Our reconstructed evolutionary history for Cynipoidea differs considerably from previous hypotheses. Rooting our analyses with non-cynipoid outgroups, the Paraulacini, a group of inquilines, emerged as sister-group to the rest of Cynipoidea, rendering the gall wasp family Cynipidae paraphyletic. The families Ibaliidae and Liopteridae, long considered archaic and early-branching parasitoid lineages, were found nested well within the Cynipoidea as sister-group to the parasitoid Figitidae. Cynipoidea originated in the early Jurassic around 190 Ma. Either inquilinism or parasitoidism is suggested as the ancestral and dominant strategy throughout the early evolution of cynipoids, depending on whether a simple (three states: parasitoidism, inquilinism and galling) or more complex (seven states: parasitoidism, inquilinism and galling split by host use) model is employed. Conclusions Our study has significant impact on understanding cynipoid evolution and highlights the importance of adequate outgroup sampling. We discuss the evolutionary timescale of the superfamily in relation to their insect hosts and host plants, and outline how phytophagous galling behavior may have evolved from entomophagous, parasitoid cynipoids. Our study has established the framework for further physiological and comparative genomic work between gall-making, inquiline and parasitoid lineages, which could also have significant implications for the evolution of diverse life histories in other Hymenoptera. 

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4. Beyond Suction-Feeding Fishes: Identifying New Approaches to Performance Integration During Prey Capture in Aquatic Vertebrates

   https://doi.org/10.1093/icb/icz094  

   Kane, Emily A. ; Cohen, Hannah E. ; Hicks, William R. ; Mahoney, Emily R. ; Marshall, Christopher D. ( June 2019 , Integrative and Comparative Biology)

   Organisms are composed of hierarchically arranged component parts that must work together to successfully achieve whole organism functions. In addition to integration among individual parts, some ecological demands require functional systems to work together in a type of inter-system performance integration. While performance can be measured by the ability to successfully accomplish ecologically relevant tasks, integration across performance traits can provide a deeper understanding of how these traits allow an organism to survive. The ability to move and the ability to consume food are essential to life, but during prey capture these two functions are typically integrated. Suction-feeding fishes have been used as a model of these interactions, but it is unclear how other ecologically relevant scenarios might reduce or change integration. To stimulate further research into these ideas, we highlight three contexts with the potential to result in changes in integration and underlying performance traits: (1) behavioral flexibility in aquatic feeding modes for capturing alternative prey types, (2) changes in the physical demands imposed by prey capture across environments, and (3) secondary adaptation for suction prey capture behaviors. These examples provide a broad scope of potential drivers of integration that are relevant to selection pressures experienced across vertebrate evolution. To demonstrate how these ideas can be applied and stimulate hypotheses, we provide observations from preliminary analyses of locally adapted populations of Trinidadian guppies (Poecilia reticulata) capturing prey using suction and biting feeding strategies and an Atlantic mudskipper (Periophthalmus barbarus) capturing prey above and below water. We also include a re-analysis of published data from two species of secondarily aquatic cetaceans, beluga whales (Delphinapterus leucas) and Pacific white-sided dolphins (Lagenorhynchus obliquidens), to examine the potential for secondary adaptation to affect integration in suction prey capture behaviors. Each of these examples support the broad importance of integration between locomotor and feeding performance but outline new ways that these relationships can be important when suction demands are reduced or altered. Future work in these areas will yield promising insights into vertebrate evolution and we hope to encourage further discussion on possible avenues of research on functional integration during prey capture.

    

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5. Range expansion of a fouling species indirectly impacts local species interactions

   https://doi.org/10.7717/peerj.3911  

   Speights, Cori J. ; McCoy, Michael W. ( October 2017 , PeerJ)

   We investigated how recent changes in the distribution and abundance of a fouling organism affected the strength of interactions between a commercially important foundation species and a common predator. Increases in the abundance of boring sponges that bioerode the calcified shells of oysters and other shelled organisms have been attributed to increased salinization of estuarine ecosystems. We tested the hypothesis that fouling by boring sponges will change the interaction strength between oysters and a common predator (stone crabs). We generated five oyster density treatments crossed with two sponge treatments (sponge and no sponge). We contrasted the interaction strength between stone crabs and fouled and non-fouled oysters by comparing the parameters of fitted functional response curves based on Rogers random predation model. We found that fouled oysters suffered higher predation from stone crabs, and that the increased predation risk stemmed from a reduction in the handling time needed to consume the fouled oysters. These findings highlight the importance of understanding the effects of abiotic changes on both the composition of ecological communities, and on the strengths of direct and indirect interactions among species. Global climate change is altering local ecosystems in complex ways, and the success of restoration, management, and mitigation strategies for important species requires a better appreciation for how these effects cascade through ecosystems.

    

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