The constant threat from a non-native predator increases tail muscle and fast-start swimming performance in Xenopus tadpoles.

Tsukasa Mori,Keiko Kashiwagi,Akihiko Kashiwagi,Tadashi Kimura,Yoichiro Kitani,Naoko Goto-Inoue,Goshi Yamamoto,Yukio Yanagisawa

doi:10.1242/bio.029926

Abstract

ABSTRACTPredator-induced phenotypic plasticity is the ability of prey to adapt to their native predator. However, owing to environmental changes, encounters with unknown predators are inevitable. Therefore, study of prey and non-native predator interaction will reveal the primary stages of adaptive strategies in prey-predator interactions in the context of evolutionary processes. Here, Xenopus tadpoles exposed to a non-native predator, a larval salamander, showed a significant increase in body weight and tail length to body length ratio. The Tmax2 test indicated a significant enhancement of the tail muscle and decrease in the relative ventral fin height in tadpoles exposed to predation risk, leading to significantly higher average swimming speeds. The analysis of muscle-related metabolites revealed that sarcosine increased significantly in tadpoles exposed to non-native predators. Multiple linear regression analysis of the fast-start swimming pattern showed that the fast-start swimming speed was determined by the time required for a tadpole to bend its body away from the threat (C-start) and the angle at which it was bent. In conclusion, morphological changes in tadpoles were functionally adaptive and induced by survival behaviors of Xenopus tadpoles against non-native predators.

Highlights

Phenotypic plasticity is the ability to produce different phenotypes in response to changes in environmental conditions, facilitating adaptation to different environmental conditions (Schoeppner and Relyea, 2005; Spitze, 1992; Trussell, 1996)
We focused on the prey-non-native predator interaction between tadpoles of Xenopus laevis, a species that occurs naturally in southern Africa and has been used widely as a model organism in biological studies (Tinsley and Kobel, 1996), and the larval salamander, H. lichenatus, which is endemic to the Tohoku area of Japan
It is well known that predator-induced phenotypic plasticity is the result of adaptation to predators, and many reports have shown that variations in morphological features in relation to various predators are the product of adaptive evolution during the prey–predator interaction as described in the Introduction

Summary

Introduction

Phenotypic plasticity is the ability to produce different phenotypes in response to changes in environmental conditions, facilitating adaptation to different environmental conditions (Schoeppner and Relyea, 2005; Spitze, 1992; Trussell, 1996). A bulgy morph formation was observed in Rana pirica tadpoles after their exposure to their main predator, the larval salamander Hynobius retardatus, which swallows tadpoles live (Kishida and Nishimura, 2004) These predator-induced morphological changes in tadpoles affect their performance; for example, they may increase their swimming speed to evade predators (Johnson et al, 2015). Tadpoles displaying phenotypic plasticity show higher survival rates when placed with native predators (Kishida and Nishimura, 2005; Van Buskirk and Relyea, 1998) These adaptive strategies involving phenotypic plasticity are found in tadpoles as a defense mechanism against specific predators to enhance their ability to escape predators and increase their chance of survival in prey-predator interactions occurring in nature

Methods

Results

Conclusion