DOI: 10.5061/dryad.h70rxwdtd
title: Data from: Spatial sorting caused by downstream dispersal: Implication for morphological evolution in isolated populations of fat minnow inhabiting small streams flowing through terraced rice paddies

description: The evolutionary forces arising from differential dispersal are known as
 “spatial sorting,” distinguishing them from natural selection arising from
 differential survival or differential reproductive success. Spatial
 sorting is often considered to be transient, because it is offset by the
 return of dispersers in many cases. However, in riverine systems, spatial
 sorting by downstream dispersal can be cumulative in habitats upstream of
 migration barriers such as weirs or falls, which can block the return of
 the dispersers. Terraced rice paddies are often found on steep mountain
 slopes in Japan and often incorporate small streams with numerous
 migration barriers. This study investigated the morphological features of
 fat minnow, Rhynchocypris oxycephalus jouyi (Cyprinidae), inhabiting
 above-barrier habitats of the small streams flowing through flood-prone
 terraced rice paddies and examined their function via a mark–recapture
 experiment. Although this study did not reveal a consistent pattern across
 all local populations, some above-barrier populations were characterised
 by individuals with a thinner caudal peduncle, thinner body, and longer
 ventral caudal fin lobes than those in neighbouring mainstream
 populations. A mark–recapture experiment during flooding showed that a
 thinner caudal peduncle and deeper body helped fat minnow avoid downstream
 dispersal and ascend a small step, and suggested that a longer ventral
 caudal fin lobe was important for ascending. These results suggest that
 the caudal morphologies of some above-barrier populations avoid or reduce
 the risk of downstream dispersal, supporting the idea that spatial sorting
 shapes functional traits, enhancing the spatial persistence of individuals
 in upstream habitats.
description: # Spatial sorting caused by downstream dispersal: implication for
 morphological evolution in isolated populations of fat minnow inhabiting
 small streams flowing through terraced rice paddies
 [https://doi.org/10.5061/dryad.h70rxwdtd](https://doi.org/10.5061/dryad.h70rxwdtd) ## Description of the data and file structure ### Files and variables #### File: EnvironmentalDataForInterpopulationComparison(Yamada\_2024).csv **Description:**  ##### Variables * Station: Name of the survey station. * StreamWidth(m): Stream width measured at 5 m intervals from the lowest point of each station. * MeanStreamWidth(m): Mean of the "StreamWidth(m)". * SD(StreamWidth): Standard deviation of the "StreamWidth(m)". * Elevation(m): Mean elevation of the lowest and highest points at each station. * StationLength(m): The length of the station along the stream. * DeltaElevation(m): The difference in elevation between the lowest and highest points of the station. * Slope(%): Slope of the station. Note: There is only a single value for each station in the columns other than "StreamWidth(m)". Therefore, those empty cells are filled with the symbol "-". #### File: InterpopulationComparison(Yamada\_2024).csv **Description:**  ##### Variables * PictureID: The ID of the measured fish image. * ForkLength(mm): Measured values of the Fork Length (mm). * DorsalCaudalFinLobeLength(mm): Measured values of the Dorsal Caudal Fin Lobe Length (mm). * VentralCaudalFinLobeLength(mm): Measured values of the Ventral Caudal Fin Lobe Length (mm). * CaudalPeduncleDepth(mm): Measured values of the Caudal Peduncle Depth (mm). * BodyDepth(mm): Measured values of the Body Depth (mm). * Habitat: Habitat category of the station. * Station: Name of the survey station. #### File: MarkRecaptureExperiment(Yamada\_2024).csv **Description:**  ##### Variables * PictureID: The ID of the measured fish image. * ForkLength(mm): Measured values of the Fork Length (mm). * DorsalCaudalFinLobeLength(mm): Measured values of the Dorsal Caudal Fin Lobe Length (mm). * VentralCaudalFinLobeLength(mm): Measured values of the Ventral Caudal Fin Lobe Length (mm). * CaudalPeduncleDepth(mm): Measured values of the Caudal Peduncle Depth (mm). * BodyDepth(mm): Measured values of the Body Depth (mm). * Section: Name of the section from which the fish were recaptured. * RetentionStatus: Retention status (0 = dispersed individuals; 1 = remaining individuals) * AscentStatus: Ascent status (0 = individuals that did not ascend; 1 = individuals that ascended) Note: To avoid data bias, individuals recaptured as mortal were also photographed and measured. #### Raw data (TIFF files) The name of the TIFF files matches the information in the "PictureID" column of the CSV files (i.e., "InterpopulationComparison(Yamada_2024).csv" and "MarkRecaptureExperiment(Yamada_2024).csv").