Spatial sorting caused by downstream dispersal: Implication for morphological evolution in isolated populations of fat minnow inhabiting small streams flowing through terraced rice paddies

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..., , , # 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: Th...