Intraspecific variation in aerobic and anaerobic locomotion: gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata) do not exhibit a trade-off between maximum sustained swimming speed and minimum cost of transport.

Jon C Svendsen,Bjã¸Rn Tirsgaard,Gerardo A Cordero,John F Steffensen

doi:10.3389/fphys.2015.00043

Abstract

Intraspecific variation and trade-off in aerobic and anaerobic traits remain poorly understood in aquatic locomotion. Using gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata), both axial swimmers, this study tested four hypotheses: (1) gait transition from steady to unsteady (i.e., burst-assisted) swimming is associated with anaerobic metabolism evidenced as excess post exercise oxygen consumption (EPOC); (2) variation in swimming performance (critical swimming speed; Ucrit) correlates with metabolic scope (MS) or anaerobic capacity (i.e., maximum EPOC); (3) there is a trade-off between maximum sustained swimming speed (Usus) and minimum cost of transport (COTmin); and (4) variation in Usus correlates positively with optimum swimming speed (Uopt; i.e., the speed that minimizes energy expenditure per unit of distance traveled). Data collection involved swimming respirometry and video analysis. Results showed that anaerobic swimming costs (i.e., EPOC) increase linearly with the number of bursts in S. aurata, with each burst corresponding to 0.53 mg O2 kg−1. Data are consistent with a previous study on striped surfperch (Embiotoca lateralis), a labriform swimmer, suggesting that the metabolic cost of burst swimming is similar across various types of locomotion. There was no correlation between Ucrit and MS or anaerobic capacity in S. aurata indicating that other factors, including morphological or biomechanical traits, influenced Ucrit. We found no evidence of a trade-off between Usus and COTmin. In fact, data revealed significant negative correlations between Usus and COTmin, suggesting that individuals with high Usus also exhibit low COTmin. Finally, there were positive correlations between Usus and Uopt. Our study demonstrates the energetic importance of anaerobic metabolism during unsteady swimming, and provides intraspecific evidence that superior maximum sustained swimming speed is associated with superior swimming economy and optimum speed.

Highlights

IntroductionVariation in locomotor performance and metabolism is linked to fitness, because both traits are often coupled with important behaviors such as predator evasion, prey capture, reproduction,(MO2active); used to calculate the critical swimming speed (Ucrit), Critical swimming speed; Umax, Swimming speed associated with the maximum metabolic rate (MO2max); Usus correlates positively with optimum swimming speed (Uopt), Optimum swimming speed defined as the speed that minimizes energy expenditure per unit of distance traveled; Usus, Maximum sustained swimming speed defined as the maximum recorded swimming speed (over 0.5 h) without any Excess post exercise oxygen consumption (EPOC) (i.e., no influence of anaerobic metabolism).www.frontiersin.orgIntraspecific aerobic and anaerobic variation migration, and dominance (Clobert et al, 2000; Walker et al, 2005; Langerhans, 2009a; Leis et al, 2009; Eliason et al, 2011; Seebacher et al, 2013; Wilson et al, 2013; Burnett et al, 2014; Killen et al, 2014; Scantlebury et al, 2014)
Variation in locomotor performance and metabolism is linked to fitness, because both traits are often coupled with important behaviors such as predator evasion, prey capture, reproduction, (MO2active); used to calculate the critical swimming speed (Ucrit), Critical swimming speed; Umax, Swimming speed associated with the maximum metabolic rate (MO2max); Usus correlates positively with optimum swimming speed (Uopt), Optimum swimming speed defined as the speed that minimizes energy expenditure per unit of distance traveled; Usus, Maximum sustained swimming speed defined as the maximum recorded swimming speed without any Excess post exercise oxygen consumption (EPOC)
This study demonstrated the energetic importance of anaerobic metabolism during unsteady locomotion

Summary

Introduction

Variation in locomotor performance and metabolism is linked to fitness, because both traits are often coupled with important behaviors such as predator evasion, prey capture, reproduction,(MO2active); Ucrit, Critical swimming speed; Umax, Swimming speed associated with the maximum metabolic rate (MO2max); Uopt, Optimum swimming speed defined as the speed that minimizes energy expenditure per unit of distance traveled; Usus, Maximum sustained swimming speed defined as the maximum recorded swimming speed (over 0.5 h) without any EPOC (i.e., no influence of anaerobic metabolism).www.frontiersin.orgIntraspecific aerobic and anaerobic variation migration, and dominance (Clobert et al, 2000; Walker et al, 2005; Langerhans, 2009a; Leis et al, 2009; Eliason et al, 2011; Seebacher et al, 2013; Wilson et al, 2013; Burnett et al, 2014; Killen et al, 2014; Scantlebury et al, 2014). Trade-offs may occur when two antagonistic traits cannot be optimized simultaneously, because the two traits pose conflicting demands on the same design feature (Damme et al, 2002). An organism may specialize in one trait at the cost of the other, in which case a trade-off may cause phenotypic differentiation (DeWitt and Scheiner, 2004; Konuma and Chiba, 2007; Herrel et al, 2009). The conflicting demands may result in organisms performing sub-optimally for both traits and constrain evolution (Lewontin, 1978; Arnold, 1992). There is evidence of a trade-off between endurance capacity and sprint speed (Langerhans, 2009b; Oufiero et al, 2011); the trade-off is not ubiquitous at the whole-organism level (Wilson et al, 2002; Vanhooydonck et al, 2014; Fu et al, 2015)

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