DOI: 10.5061/dryad.08kprr588
title: Wall-following – phylogenetic context of an enhanced behaviour in stygomorphic <em>Sinocyclocheilus</em> (Cypriniformes: Cyprinidae) cavefishes

description: With 75 known species, the freshwater-fish genus Sinocyclocheilus is the
 largest cavefish radiation in the world, emerging as a model system for
 evolutionary studies. They show multiple adaptations for cave dwelling
 (stygomorphic adaptations), which include a range of traits such as eye
 degeneration (Normal-eyed, Micro-eyed and Eyeless), depigmentation of
 skin, and in some species, the presence of “horns”. Their behavioural
 adaptations to subterranean environments, however, are poorly understood.
 Wall-following (WF) behaviour, where an organism remains in close contact
 with the boundary demarcating its habitat when in the dark, is a peculiar
 behaviour observed in a wide range of animals and is enhanced in some cave
 dwellers. Hence, we hypothesize wall-following to be present also in
 Sinocyclocheilus, possibly enhanced in Eyeless species compared to species
 with visual cues (Normal / Micro-eyed species). Using 13 species
 representative of Sinocyclocheilus radiation and eye-morphs, we designed a
 series of assays, based on pre-existing methods for Astyanax mexicanus
 behavioural experiments, to examine wall-following behaviour under three
 stimulation conditions. Our results indicate that eyeless species exhibit
 significantly enhanced levels of WF compared to Normal-eyed species, with
 Micro-eyed forms demonstrating intermediate levels. Using a mtDNA based
 dated phylogeny (chronogram with four clades A – D), we traced the degree
 of WF of these forms to outline common patterns. We show that intensity of
 WF behaviour is high in the subterranean clades (B & C) compared
 to clades with free-living species (A & D). Experiments on WF
 behaviour revealed that eyeless species are highly sensitive to
 vibrations, whereas normal-eyed species are the least sensitive. Since WF
 behaviour is present to some degree in all Sinocyclocheilus species, and
 given that these fishes evolved in the late Miocene, we identify this
 behaviour as being ancestral with WF enhancement related to cave
 occupation. Our results from this diversification-scale study of cavefish
 behaviour suggest that enhanced wall-following behaviour may be a
 convergent trait across all stygomorphic cavefish lineages.
description: # Wall-following – phylogenetic context of an enhanced behaviour in
 stygomorphic *Sinocyclocheilus* (Cypriniformes: Cyprinidae) cavefishes
 This readme file was generated on 2024-03-05 by Bing Chen GENERAL
 INFORMATION Date of data collection: 2019-2021 Geographic location of data
 collection: Guangxi University, NanNing, China DATA & FILE OVERVIEW 1.
 "Sinocyclocheilus_supplementary_data1.csv": Raw data collection
 about wall-following behaviour from laboratory measurements. All
 Abbreviations were set the same as "TABLE A2. The definition and
 measurements of all variables in this study" * **WF**:Wall-following
 * **SL**: Standard Length * **Pfin**: Pectoral fin * **S**: Stimulation *
 **WF-Distance**: Distance fish swam in wall-following range/standard
 length (SL) * **WF-Time**: Time that fish spend for wall-following/whole
 testing time (%) * **WF-Resting Time**: Time of swimming speeds &lt;0.2
 (cm/s)/whole testing time (%) * **WF-Speed**: Tested by EthoVision XT as
 average speed (SL/s) * **WF-Max Speed**: The maximum speed fish reached in
 one assay (SL/s) * **WF-Frequency**: The times fish swimming into
 wall-following range (–) * **S-Time**: Time fish swimming in stimulation
 range (%) * **S-Speed**: Average speed in stimulation range (SL/s) *
 **S-Max Speed**: The max speed in stimulation range (SL/s) *
 **S-Frequency**: The times fish swam into stimulation range (–) *
 **SE-diameter**: Diameter of eyeball/diameter of eye orbit (–) *
 **Standard Length**: The length from the tip of mouth to the end of caudal
 fin (cm) * **Angle3**: Angle of approaching to stimulation, the third time
 (degree) * **Angle2**: Angle of approaching to stimulation, the second
 time (degree) * **Angle1**: Angle of approaching to stimulation, the first
 time (degree) * **Distance3**: Distance of the third approach (cm) *
 **Distance2**: Distance of the second approach (cm) * **Distance1**:
 Distance of the first approach (cm) 1.
 "Sinocyclocheilus_supplementary_data2.csv": Raw data collection
 from wall-following behaviour in the "Approaching distance,
 angle" laboratory measurements. METHODOLOGICAL INFORMATION 1.
 Description of methods used for collection/generation of data:
 Measurements were collected from the lab work. 2. Methods for processing
 the data: Behaviour was recorded by Cannon infrared camera (Cannon XF 405)
 and analysis was measured by software "EthoVision XT v.15 (Noldus IT,
 Wageningen, Netherlands)".