Dataset DOI: 10.5061/dryad.rxwdbrvrv

Description of the data and file structure

A. artaxerxes females were collected in the Uppsala area in the province of Uppland, Sweden, between July 2-13, 2024 (localities: 59.8359 N, 17.5880 E; 59.8595 N, 17.5783 E & 59.8394 N, 17.5566 E). The two host plant species G. sylvaticum and G. sanguineum were also collected in the province of Uppland (localities: 59.8359 N, 17.5880 E; 59.8595 N, 17.5783 E; 59.8394 N, 17.5566 E & 60.5093 N, 17.5973 E). During the field work, we observed that both G. sylvaticum and G. sanguineum were present in the localities where the butterflies were collected. We placed the collected A. artaxerxes females (n = 28) individually in 40 x 40 x 40 cm mesh cages with plastic roofs (n = 4). However, only a minority of the females oviposited during the host plant preference test, resulting in 7 experimental replicates. We cut the host plants to similar sizes, approximately 30 cm in height, and placed them individually in plastic containers with water. In each cage, we placed four containers with plants, one in each corner with the same host plant species in opposite corners. We switched the placement of the host plant species between the cages. In the centre of each cage, we placed a feeding station consisting of Cirsium flowers and sugar water. The host plant preference test ran for 72 hours with an 18-hour light + 6-hour darkness regime (light between 3 a.m. and 9 p.m. and dark between 9 p.m. and 3 a.m., which approximately corresponds to conditions in Uppland at the time of collection). After 72 hours, we counted the number of eggs laid by each female on each host plant species.

During the host plant preference test, 346 eggs were laid by the 7 A. artaxerxes females. The eggs were laid individually (as opposed to in clusters). The larvae hatching from the eggs were raised on the same host plant as the egg was laid. Host plants were replaced regularly so that larvae always had access to fresh food. If host plants were about to dry up, we placed new plants next to them in the containers. The larvae were raised under the same light conditions used during the host plant preference test (18 hours light + 6 hours dark). Beginning on day 8 after the start of the host plant preference test, we photographed the larvae using a Lumenera Infinity 2-5C microscopy camera mounted on a Leica M165C stereo microscope and the software Infinity analyze version 6.2 (Lumenera Corporation, 2013). We photographed each cohort of larvae every 3^rd day for 12-15 days. For each day and cohort, we photographed up to 20 randomly chosen larvae (5 larvae per plant). To minimize handling, we photographed the larvae on the host plants. We measured the surface area (mm²) of the photographed larvae using the polygon selections tool in the software ImageJ version 1.54 (Schneider et al. 2012). In total, we took 370 size measurements.

For the geographic distribution, we downloaded data of reported observations of A. artaxerxes, G. sylvaticum and G. sanguineum in the province of Uppland, Sweden, from the citizen science database Species Observation System (Artportalen) (SLU Swedish Species Information Centre n.d.) on November 27, 2024. For the distribution of A. artaxerxes, we used 1,431 observations reported between years 2000-2024. For the distribution of G. sylvaticum and G. sanguineum, we also used data from an inventory of the plants of Uppland (Jonsell 2010). The plant inventory was conducted between years 1991-2005 in 2,742 grid cells of 2.5 × 2.5 km covering the province of Uppland. The downloaded data showed the grid cells in which G. sylvaticum and G. sanguineum were noted during the inventory. We created a map of the distribution of A. artaxerxes, G. sylvaticum and G. sanguineum in Uppland using the 2.5 × 2.5 km grid cells from the plant inventory in the GIS software QGIS version 3.40 (QGIS Development Team 2024).

Files and variables

File: distribution.csv

Description:  Geographical coordinates for the host plants (G. sylvaticum, G. sanguineam) and the butterfly (A. artaxerxes) in tbe province of Uppland, Sweden. Coordinates for host plants refer to presence in 2.5*2.5 km grid cell from an atlas inventory, while the coordinates for the butterfly refer to actual observations from citizen science.

Variables

• Species: The species (G. sylvaticum, G. sanguineam or A. artaxerxes)
• East: Longitude in WGS 84
• North: Latitude in WGS 84

File: expected_observed.csv

Description: 

Variables

• Number of squares: Number of grid cells each combination of species was expeced or observed
• Species: The host plant species
• Condition: Whether the number of grid cells was observed from data, or expected from the chi2 analysis

File: larvae.csv

Description: 

Variables

• Photo: Unique ID of the photo
• Female: Female who laid the egg
• Species: Host plant the larvae was feeding on
• Day: Days since oviposition
• Date: Date the photo was taken
• Size: Size (surface area) of the larvae in mm^2
• Density: the number of larvae on the individual host plant

File: oviposition.csv

Description: 

Variables

• Female: Female ID
• Species: The species of host plant the female oviposited on
• Number of eggs: The number of eggs oviposited by the female on the given host plant

File: Larvae_analysis_cleaned.R

Description: R code for analysis of larval growth

File: Oviposition_analysis_cleaned.R

Description: R code for analysis of oviposition preference

File: Distribution_analysis_cleaned.R

Description: R code for analysing distribution in a chi2 framework

File: Distribution_glm_cleaned.R

Description: R code for analysing distribution in a regression framework, including tests for spatial autocorrelation

Code/software

Data were analysed in R 4.4.1.

The packages used for each analysis are documented in each R script

The files used for each analysis are documented in each R script