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1. Predation pressure in amphidromous gobies: how their morphology is selected by predator species.

Author

Lagarde, R. and Ponton, D.

Subjects
*PREDATION, *PECTORAL fins, *SPECIES, *MORPHOLOGY, *PREDATORY animals, *GOBIIDAE
Abstract

The morphology of an individual can improve its ability to escape predators and ultimately its chances of survival. Sicydiine fishes reproduce in rivers, and their larvae develop in the sea. Once juveniles arrive in rivers, they face numerous predatory fish species. Some juveniles can climb above the first waterfall where the abundance of predatory species is reduced. For individuals that do not climb waterfalls, survival only depends upon their ability to avoid predation. While the factors that affect climbing performance of sicydiines have been extensively described, the information is scarce concerning their predator escape performance. Our experimental study aimed to describe how the predation pressure imposed by three predatory fish species (Eleotris klunzingerii, Kuhlia rupestris, and Anguilla marmorata) affects the individual morphology of juveniles of two sicydiine species from Reunion Island (Cotylopus acutipinnis and Sicyopterus lagocephalus). Individuals which survived predation had a more streamlined body and larger and/or longer pectoral fins for the two sicydiine species, whereas others morphological variables differed with the predator species. Body form of individuals that survived predation also differed from the body form of individuals that climbed waterfalls. The different prey's body forms under selection by the three predator species should be considered in further studies that could address the tradeoff in sicydiines between climbing waterfalls and escaping predation in the field. For example, a careful description of the predator community would help to understand which predator(s) sicydiines juveniles need to escape in downstream reaches and how this particular predation pressure can select body forms. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Intra- and inter-specific morphological diversity of amphidromous gobies influences waterfall-climbing performance

Author

Lagarde, R., Borie, G., Blob, R. W., Schoenfuss, H. L., and Ponton, Dominique

Subjects
fish, locomotion, gobies, morphology, amphidromous, selection, diadromy, performance
Abstract

The morphology of an individual can affect functional performance and, ultimately, survival and fitness. To study these links, a first step is to evaluate the relationship between morphology and performance. Sicydiine fishes are an interesting model for such studies, because successful completion of their life cycle depends on a functionally demanding task: climbing waterfalls when they return to freshwater from the ocean. Previous studies identified two different climbing modes among sicydiines: 'inching' and 'powerburst'. Relationships between morphology and climbing performance have been found for inching and powerburst species present on different islands from distant oceans (Pacific and Caribbean), but species from the same island have not been compared. In this study, we challenged two different sicydiine species from Reunion Island to an artificial climbing ramp: the inching climber Sicyopterus lagocephalus and the powerburst climber Cotylopus acutipinnis. For each species, we evaluated differences in morphology between successful and unsuccessful climbers. We predicted that species with similar climbing styles (S. lagocephalus and S. stimpsoni) would show differences between successful and unsuccessful climbers that more closely resembled each other than differences between successful and unsuccessful climbers across species from the same island (S. lagocephalus and C. acutipinnis). This prediction was only partially met. S. lagocephalus individuals with a streamlined body showed better climbing performance, as observed for S. stimpsoni. However, the size of the pelvic sucker, which fish use to attach to the substrate while resting, appeared less important for S. lagocephalus than for S. stimpsoni and C. acutipinnis. Instead, the size of the mouth, which inching species use to attach to the substrate while moving up, seemed important for S. lagocephalus but not for other species. Thus, differences in the morphology-performance relationship among sicydiines may relate not only to differences in climbing mode, but also to species-specific specializations within each climbing mode.

Published
2018

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