DOI: 10.5061/dryad.q83bk3jv8
title: Data from: Phenotypic plasticity drives the development of laterality in the scale-eating cichlid fish <em>Perissodus microlepis</em>

description: Phenotypic plasticity, in which traits change in response to environmental
 conditions, is closely related to predator–prey interactions and
 speciation. The scale-eating cichlid fish Perissodus microlepis exhibits
 marked left–right differences in predatory behaviour and mouth morphology.
 While phenotypic plasticity is hypothesized to contribute to the formation
 of laterality, direct evidence remains scarce. We examined how plasticity
 shapes laterality by analysing the predatory behaviour and mandibular
 changes under different foraging conditions: picking granulated feed
 (non-scale-eating) and tearing scales from prey fish. During the predation
 experiment, the number of attacks increased over time. Behavioural
 analysis revealed that the mean inter-individual distance from scale-eater
 to prey gradually decreased, whereas mean swimming activity increased.
 Morphological analysis of the mandible showed elongation of the dentary
 bone along the anterior–posterior axis in the scale-eating groups compared
 to the non-scale-eating group. Furthermore, mandible height was
 significantly greater on the dominant side, with the degree of asymmetry
 increasing with scale-eating experience. This strongly suggests that
 phenotypic plasticity contributes to the enhancement of laterality and
 promotes disruptive selection of lateral morphs. This study advances our
 understanding of the unique adaptation in P. microlepis and highlights the
 importance of feeding experience in shaping adaptive traits within the
 cichlid lineage.
description: The scale-eaters used in our study were bred in our laboratory
 with help of the World Freshwater Aquarium Aquatotto Gifu in Japan. We
 prepared three groups of specimens with different levels of scale-eating
 experience. The predation experiments were conducted daily for 127 days
 from the start, and predation was recorded every few days with a video
 camera; 32 videos of the Prey 1 group and 29 videos of the Prey 2 group
 were obtained. To detect the position of each scale-eating fish and prey
 fish in the tank, we fine-tuned the pre-trained neural network YOLO v3 on
 our dataset taken from the predation experiment. To assess the
 morphological features of the mouth of <em>P. microlepis</em>,
 we performed a geometric morphometric analysis on the lower
 jawbone.
description: # Data from: Phenotypic plasticity drives the development of laterality in
 the scale-eating cichlid fish *Perissodus microlepis* Dataset DOI:
 [10.5061/dryad.q83bk3jv8](10.5061/dryad.q83bk3jv8) ## Description of the
 data and file structure The scale-eaters used in our study were bred in
 our laboratory with the help of the World Freshwater Aquarium Aquatotto
 Gifu in Japan. We prepared three groups of specimens with different levels
 of scale-eating experience. The predation experiments were conducted daily
 for 127 days from the start, and predation was recorded every few days
 with a video camera; 32 videos of the Prey 1 group and 29 videos of the
 Prey 2 group were obtained. To detect the position of each scale-eating
 fish and prey fish in the tank, we fine-tuned the pre-trained neural
 network YOLO v3 on our dataset taken from the predation experiment. To
 assess the morphological features of the mouth of *P. microlepis*, we
 performed a geometric morphometric analysis on the lower jawbone. ####
 File 1: Inter-individual_distance.csv **Description:**  Relationship
 between the number of experimental days and inter-individual distance
 between scale-eating fish and prey fish.  #### File 2:
 Swimming_distance_of_scale-eaters.csv **Description:**  Relationship
 between the number of experimental days and the swimming distance of
 scale-eaters. Swimming activity was positively correlated with the number
 of experimental days in both groups. #### File 3:
 The_number_of_attacks_in_10-min.csv **Description:**  Relationship between
 the number of experimental day s and the number of attacks in the
 experimental 10-min period. #### File 4:
 The_number_of_attacks_in_the_first_minute.csv **Description:**  Change
 over time in the number of attacks in the first minute of the experiment.
 #### File 5: PCA_of_the_lower_jawbone.csv **Description:**  Scatter plots
 of PC1 and PC2 from principal component analysis of the lower jawbone. In
 AorBorC column, "A" is Prey 1 group, "B" is Prey 2
 group, and "C" is Non-scale-eating group. In Dominance,
 "D" is a dominant side jaw, and "N" is a non-dominant
 side jaw. #### File 6: The_asymmetry_index_of_mandibular_height.csv
 **Description:**  The asymmetry index of mandibular height in Prey 2
 group, Prey 1 group, and the non-scale-eating group. #### File 7:
 The_swimming_distance_of_prey.csv **Description:**  Relationship between
 the number of experimental days and the swimming distance of prey fish. 
 #### File 8:
 Mandibular_asymmetry_of_wild-caught_fish_and_isolated-rearing_fish.csv
 **Description:**  Comparison of mandibular asymmetry between wild-caught
 fish and isolated-rearing fish. ##### Variables * Inter-individual
 distance: to determine changes in predation behavior with scale-eating
 experience, we took the coordinates during the first minute after the
 introduction of prey and calculated the inter-individual distance between
 them. The unit for inter-individual distance is pixels. * Swimming
 distance: using optical flow, we calculated the swimming activity of
 scale-eating fish, defined as the total swimming distance of the fish in
 the movie. The unit for swimming distance is pixels. * Number of
 attacks: we counted the number of attacks during a 10-minute period based
 on video data. - Asymmetry index: we measured the length of the entire
 posterior dimension of each lower jaw.