Abstract
Lateralization, i.e. the preferential use of one side of the body, may convey fitness benefits for organisms within rapidly-changing environments, by optimizing separate and parallel processing of different information between the two brain hemispheres. In coral reef-fishes, the movement of larvae from planktonic to reef environments (recruitment) represents a major life-history transition. This transition requires larvae to rapidly identify and respond to sensory cues to select a suitable habitat that facilitates survival and growth. This ‘recruitment’ is critical for population persistence and resilience. In aquarium experiments, larval Acanthurus triostegus preferentially used their right-eye to investigate a variety of visual stimuli. Despite this, when held in in situ cages with predators, those larvae that previously favored their left-eye exhibited higher survival. These results support the “brain’s right-hemisphere” theory, which predicts that the right-eye (i.e. left-hemisphere) is used to categorize stimuli while the left-eye (i.e. right-hemisphere) is used to inspect novel items and initiate rapid behavioral-responses. While these experiments confirm that being highly lateralized is ecologically advantageous, exposure to chlorpyrifos, a pesticide often inadvertently added to coral-reef waters, impaired visual-lateralization. This suggests that chemical pollutants could impair the brain function of larval fishes during a critical life-history transition, potentially impacting recruitment success.
Highlights
Brain asymmetry and the preference to use one side of the body over the other to accomplish actions, has been identified in a variety of vertebrate and invertebrate species[1,2,3,4,5]
This study identified a strong preference for the right eye when inspecting stimuli from either a mirror, conspecifics, or a predator
While a preference for the using the right eye, or the left hemisphere of the brain, to categorize familiar stimuli has been seen in another coral reef fish: Myrispristis pralinia[8], our results suggest that this preference extends to unfamiliar stimuli
Summary
Brain asymmetry and the preference to use one side of the body over the other to accomplish actions (termed lateralization), has been identified in a variety of vertebrate and invertebrate species[1,2,3,4,5]. The relationship between brain morphology, lateralization, social interactions, and anti-predator behaviors in early-life-stage coral reef fishes remains largely unknown[8, 45, 46, 51, 54,55,56], with the role of behavioral lateralization during recruitment only initially assessed[55, 56] These recent experiments have primarily used detour tests, which examine potential turning bias of individuals in a context of vigilance, and revealed that such lateralized behaviors can be associated with anti-predator response phenotypes and survival benefits[55,56,57]. Whether this pollutions affect or not behavioral lateralized processes remains unknown[71]
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