Intra‐ and inter‐specific morphological diversity of amphidromous gobies influences waterfall‐climbing 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 Réunion 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.

Pre‐ to post‐fledging carryover effects and the adaptive significance of variation in wing development for juvenile songbirds

“…Ultimately, such findings are consistent with studies on development, locomotion and survival in juveniles of other taxa (e.g. Carrier, 1996; Lagarde, Borie, Blob, Schoenfuss, & Ponton, 2018; Landberg & Azizi, 2010) and those highlighting carryover effects in juveniles during the most critical periods of their life (e.g. Jones et al., 2017; Morgan & Metcalfe, 2001; Van Allen et al., 2010; Vonesh & Bolker, 2005).…”

Structure of small tropical island freshwater fish and crustacean communities: A niche‐or dispersal‐based process?

“…However, a stronger variation of abundance of these two trophic groups along elevation and slope gradients would have been expected if dispersal‐based process shapes their distribution. Indeed, inter‐individual difference in locomotor performances can limit species abundances in upstream sites with only the most performant individuals being able to reach these sites (Lagarde et al, 2018; Lagarde et al, 2020). In this context, other environmental factors such as the availability of food resources (Julius et al, 2005), prey/predators or competitive interactions (Monti & Legendre, 2009), can be more essential for shaping primary consumers and omnivore communities.…”

Functional Diversity of Evolutionary Novelties: Insights from Waterfall-Climbing Kinematics and Performance of Juvenile Gobiid Fishes

“…Given that climbing behaviors are components of a migratory phase of the life cycle, to what extent might differences in performance impact features such as the in-stream distributions and upstream penetration of species? In La Réunion, C. acutipinnis has a higher failure rate during attempted climbs than faster S. lagocephalus ( Lagarde et al. 2018 ), and it takes C. acutipinnis 20–25% more days to migrate to adult upstream habitats ( Lagarde et al 2020 ).…”