A test of the abundant-center hypothesis for stream fishes

The abundant-center hypothesis (ACH) provides a conceptual model for predicting range-wide distributions of species abundance, suggesting that abundance peaks in the center of the geographic range and declines towards range edges. Empirical studies testing the ACH and its subsequent derivations predominantly occurred in terrestrial systems and reported mixed support. Moreover, none of these models consider the possibility of multiple geographic areas of elevated abundance (which we refer to as abundant cores). Naturally, dispersal limited species may exhibit multiple abundant cores, requiring refinement of the ACH. We used fish species abundances from 29,206 community monitoring surveys and weighted geospatial kernel density estimation to identify the number of abundant cores for 64 freshwater fish species. We regressed the number of abundant cores against range size and body size to test if larger geographic distributions and body sizes contain more abundant cores than smaller distribu..., , # A test of the abundant-center hypothesis for stream fishes

Dataset DOI: [10.5061/dryad.r4xgxd2r1](10.5061/dryad.r4xgxd2r1)

## Description of the data and file structure

The following files include data and code for running analyses in the associated study. The study hinges on the KDE (kernal density estimates) that inform the distribution modeling. 

### Files and variables

#### File: Ecography\_Rproject.Rproj

**Description:** R Project file for the analysis

#### File: ACH\_code.R

**Description:** R script for running the abundance center hypothesis analysis

#### File: KDEcoreResults\_Ecography.csv

**Description:** CSV data for the kernal density data

##### Variables

* Scientific_Name: Scientific name of stream fishes in study
* Common_Name: Common name of stream fishes in study
* avg.c10: average number of c10 cores estimated
* sd.cores10: standard deviation of c10 core estimates
* c10_SE: standard error of c10 core estimates
* c10_2.5: 2.5% quantile of c10 core estimates
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