Growth rate and locomotor performance tradeoff is not universal in birds.

Tao Zhao,Zhiheng Li

doi:10.7717/peerj.8423

Abstract

Though a tradeoff between growth rate and locomotor performance has been proposed, empirical data on this relationship are still limited. Here we statistically analyze the associations of growth rate and flight ability in birds by assessing how growth rate is correlated with three wing parameters of birds: flight muscle ratio, wing aspect ratio, and wing loading. We find that fast-growing birds tended to have higher flight muscle ratios and higher wing loadings than slow-growing birds, which suggests that fast-growing birds may have better takeoff performance, but lower efficiency in maneuvering flight. Accordingly, our findings suggest that the relationship between growth rate and flight ability is more complex than a simple tradeoff. Since the hindlimbs also contribute greatly to the locomotion of birds, future investigations on the relationship between growth rate and hindlimb performance will provide more insights into the evolution of birds.

Highlights

Growth rates vary considerably among different taxa and organisms (Arendt, 1997; Case, 1978; Ricklefs, 1973, 1968)
Flight muscle ratio was calculated as mass of flight muscles divided by body mass; aspect ratio as wing span squared divided by wing area; wing loading as body mass divided by wing area
Birds with higher flight muscle ratios tended to grow faster than birds with smaller flight muscle ratios (Fig. 1). In all these three models, latitude was significantly correlated with growth rate (P = 0.032, effect size = 0.25 in model 1; P = 0.001, effect size = 0.29 in model 2; P = 0.002, effect size = 0.28 in model 3); birds from higher latitudes tended to grow faster than birds from lower latitudes

Summary

Introduction

Growth rates vary considerably among different taxa and organisms (Arendt, 1997; Case, 1978; Ricklefs, 1973, 1968). Rapid growth allows organisms to shorten the duration of reaching maturity when they are vulnerable to predators (Case, 1978). Rapid growth may reduce longevity (Gabriela, 2018; Metcalfe & Monaghan, 2003) and reduce investment in other functions, because overall resources are limited (Arendt, 1997; Dmitriew, 2011; Martin et al, 2011). One of the main functions that are suggested to be negatively affected by rapid growth is locomotor performance (Billerbeck, Lankford & Conover, 2001; Dmitriew, 2011; Lee, Monaghan & Metcalfe, 2010). Billerbeck, Lankford & Conover (2001) showed that within the Atlantic silversides (Menidia menida), the fast-growing fish have lower maximum prolonged and burst swimming speeds than slow-growing ones

Methods

Results

Discussion

Conclusion