Figure 1.

Body weight of island and mainland populations in the study area. (a) Map of coastal British Columbia, Canada, showing the study area. The colour of collection points indicates the median weight of P. maniculatus populations, and circle area indicates sample size. Collection sites within 8 km of each other were combined into a single site. Only adult males were included. Sampled islands are shaded dark grey, non-sampled islands light grey and mainland areas (including Vancouver Island) light green. Live deer mice were collected from Saturna Island (SI) and the Malcolm Knapp Research Forest (MKRF) to found laboratory colonies (starred). (b) Genetic PCA of 54 deer mice from Saturna Island, Pender Island (PI) and the Malcolm Knapp Research Forest, based on 80 248 genome-wide variants. The percentage of variance explained by the first and second PC is provided. (c) Admixture analysis of the dataset from (b) with a cluster number of K = 3. (d) Bayesian divergence time estimates of island and mainland P. maniculatus populations and the outgroup P. keeni based on 7092 variants from 14 specimens. Grey bars represent 95% highest posterior density intervals. The scale bar is in thousands of years (kyr). (Online version in colour.)