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This file was generated on 2026-04-26 by NIKLAS BECKERS


A GENERAL INFORMATION

1. Title of the dataset:
Data on the distribution and body sizes of two size morphs in the arctic-alpine beetle Amara alpina (Paykull, 1790)

2. Brief description of the research project and its aims: 
We studied how the distribution of body sizes in A. alpina across Northern Europe relates to the environment. Our aim was to confirm the existence of these two distinct phenotypes of the species and identify environmental drivers to explain their distribution. Our hypothesis was that the differentiation of the species is driven by patterns of snowmelt. We tested this by using a machine learning approach to model body sizes against environmental variables of a dataset with 1x1 km spatial and daily average temporal resolution. 
The data provided here are the measurements of Amara alpina pronotum width with accompanying information on environemtal variables. Climate data are publicly available from www.senorge.no under the respective coordinates given for each specimen.

3. Author Information
	A. Investigator Contact Information
		Name: NIKLAS BECKERS
		Institution: Dept. of Geography, University of Bonn
		Address: Meckenheimer Allee 166, 53115 Bonn
		Email: nbeckers@uni-bonn.de

		Name: NILS HEIN
		Institution: Helmholtz Centre for Environmental Research, Leipzig; 
		Address: Permoserstraße 15 04318 Leipzig
		Email: nils.hein@ufz.de

		Name: KIM A. VANSELOW
		Institution: Institute of Geography, University of Erlangen
		Address: Wetterkreuz 15, 91058 Erlangen
		Email: kim.vanselow@fau.de
			
		Name: JOERG LOEFFLER
		Institution: Dept. of Geography, University of Bonn
		Address: Meckenheimer Allee 166, 53115 Bonn
		Email: nbeckers@uni-bonn.de

	B. Project Supervisor (Principal Investigator) Contact Information
		Name: NIKLAS BECKERS
		Institution: Dept. of Geography, University of Bonn
		Address: Meckenheimer Allee 166, 53115 Bonn
		Email: nbeckers@uni-bonn.de		

	C. In case of questions related to this dataset, please contact:
		Name: NIKLAS BECKERS
		Institution: Dept. of Geography, University of Bonn
		Address: Meckenheimer Allee 166, 53115 Bonn
		Email: nbeckers@uni-bonn.de				

4. Date of data collection: 
1985-08-08 until 2010-09-28

5. Information about funding sources that supported the collection of the data: 
No external funding received; Data was collected in other projects and reassembled for this studies' purpose

6. Language of the dataset:
English

7. Geographic location of data collection:
Norwegian Scandes Mountain Range. For our study, we assembled specimens from the entire latitudinal and elevational ranges of the species´ Northern European distribution (Lindroth, 1989). 
Along the latitudinal gradient, we included specimens from a southernmost location 60° 34’ 27.192’’ N to 70° 25' 9.516’’ N. 
Along the elevational gradient, we collected specimens from 4 m a.s.l. in the North of Norway to about 1565 m a.s.l. in the southern Norwegian Scandes. 
Our earliest sample dates to 1985, the most recent specimens to 2010. Older specimens were available in Museum collections across Norway. 
Our analysis required that our data can be coupled to seNorge.no raster cells for climate data, which limited the preliminary dataset to specimens which had been collected post-1950 and provided with sufficient spatial information. 
Therefore, our data consisted largely of specimens collected repeatedly in two main long-term ecosystem research areas: 
Finse (Østbye & Hågvar, 1996; Hågvar et al., 2017) and Vågå (Löffler, 2002; Hein et al., 2014; Beckers et al., 2018; Löffler & Pape, 2020) in the Norwegian Scandes. 
The University Museum of Trondheim (NTNU Museum, Prof. Frode Ødegaard) and University Museum of Bergen (UiB, Dr. Steffen Roth) kindly provided samples for our study; 
not all of these could be included in the final study for statistical reasons.



B DATA & FILE OVERVIEW

1. File List: 
Aalp_sizes.txt - textfile containing data, see variable description below
readme_beckers-et-al.txt - data documentation of the dataset

2. Are there multiple versions of the dataset?
No

3. Relationship between files: 
Data supplement table and Readme.

4. Additional related data collected that was not included in the current data package: 
Some measured specimens (for example UiB collection specimens, see section A number 7) were not included due to insufficient information on sampling location or time. Data can be requested from the author.



C SHARING/ACCESS INFORMATION

1. Was data derived from another source?: No

2. Licenses/restrictions placed on the data: 
Creative Commons CC-BY-4.0 International License

3. Links to publications that cite or use the data
The article "Snowmelt timing determines the distribution of two size morphs in the arctic-alpine beetle Amara alpina (Paykull, 1790)" that this dataset is supplement to is currently under review. 
Upon the publication of the article, its full citation will be updated in the dataset’s metadata field “Related Publication”.



D METHODOLOGICAL INFORMATION

1. Description of methods used for collection/generation of data: 
Collection stemming from pitfall trapping of analyzed individuals, collected individuals from NTNU University Museum (https://www.ntnu.edu/museum/research-and-collections) and Sigmund Hågvår (private collection)

2. Methods for processing the data: 
We used the width of the pronotum (mm) at its base as a proxy for body size. 
The base of the pronotum is marked by a lateral tooth (Lindroth, 1985), making this approach easily applicable. 
Specimens were digitally photographed under a stereomicroscope with 56-100x magnification for specimens from our University of Bonn Collection (GIUB collection). 
These specimens were placed on a sand bed within a petri dish to ensure that pictures were taken from a perpendicular angle. 
The images were adjusted to scale. 
Additional images with attached scale were provided by the University Museum of Trondheim (NTNU collection). 
Measurements were then made using the ImageJ software (Rasband, 2016). 
Specimens stemming from S. Hågvar’s private collection were measured using a handheld caliper. 
We rounded photogrammetric results to the nearest 0.05 mm, according to the accuracy of caliper results.

3. Instrument- and/or software-specific information needed to interpret the data: 
Data can be accessed with any text editor (i.e., MS Editor). 
We recommend the use of R version 4.5.1 (2025-06-13 ucrt; https://www.r-project.org/), via R Studio (https://posit.co/download/rstudio-desktop)

4. People involved in sample collection, processing, analysis and/or submission: 
Niklas Beckers, Sigmund Hågvår (retired).


E DATA-SPECIFIC INFORMATION FOR: Aalp_sizes.txt


1. Variable list including full names and definitions (please spell out abbreviated words) of column headings for tabular data: 

Size: Pronotum width of A. alpina, raw values as measured
SizeR: Pronotum width of A. alpina, rounded to the nearest .05 mm for analysis

Spatial variables:
Elev: Elevation of sampling sites, in some cases approximated based on GPS coordinates [m] a.s.l. (meters above sea level)
Lat: Latitude; [decimal degrees]
Long: Longitude; [decimal degrees]
Region: study region [character string]

Others:
Year: Year of sampling
Sex: Sex of specimen
Photo.ID: file name of corresponding image files. Images can be shared upon request.
Sorting: numeric vector to sort data in a processor, e.g. Excel. 


2. Units of measurement used:
See above definition of variables.

3. Missing data codes/symbols: 
no missing data