Figure captions
Figure 1. (a) Figure showing the main study selection
criterion. The population (marked with circle) was the observation level
for analysis, and only study systems with a minimum of two islands (I1,
I2) and two mainland populations (M1, M2) were considered. Circle size
indicates possible differences between the mean of a specific phenotypic
trait or a neutral genetic diversity measure. We calculated the log
ratio between the largest and the smallest values for paired island
populations and paired mainland populations respectively for each
phenotypic trait and neutral genetic diversity measure (Y axis in (b)).
(b) Expectations for a positive effect of geographic and macroclimatic
distances on the calculated response variables within island and
mainland systems. We expected stronger effects of geographic distance on
mean phenotypes and neutral genetic diversity in island systems compared
to the mainland systems, and we did not expect the effects of
macroclimatic distance to differ between the two system types. We
expected stronger responses of phenotypic traits compared to the neutral
genetic diversity.
Figure 2. (a) The global representation of 1019 island
(turquoise dots) and 813 mainland populations (orange dots) with
population-level phenotypic traits and genetic diversity data studied
comparatively in island and mainland systems for 112 species. (b) Number
of species in different taxonomic groups included in this study
(vascular plants were sub-grouped into Tree or Shrub and Herbaceous life
forms). (c) Two sample maps showing the geographic distribution of
populations studied comparatively in island and mainland systems for a
bird (Melospiza melodia ) and a plant (Elymus glaucus )
species.
Figure 3. Log-ratio of phenotypic trait values between island
populations (turquoise) and between mainland populations (orange) for
100 sampled datasets. Horizontal black lines represent intercept
estimates for each of the 100 sampled datasets, and the point with a
vertical dashed line represent the mean and the overall 95% credibility
interval. Points are jittered horizontally for better visualisation.