Bioclimatic data
The method of principal components was used to identify the influence of
environmental variables on the sex ratios in each population. PCA was
applied to sex ratios and climatic parameters. Climatic factors for the
data matrix were retrieved from WorldClim (Fick and Hijmans 2017) and
ENVIREM (Title and Bemmels 2018) and were designated as follows: Bio1,
average mean temperature; Bio7, temperature annual range; Bio12, annual
precipitation; Elev, elevation; and Arid, Aridity Index. We selected the
climatic parameters by following their importance for the sex ratios in
populations of gynodioecious plants. The values for each site were
determined at a very high spatial resolution of 30 seconds
(~1 km2). Close relationships
(positive or negative) between climatic parameters and the frequency of
females in populations with the main components were considered as the
influence of various environmental variables on the variation in the
frequency of females. An arcsine transformation of the females’
frequency in populations was performed before determining the main
components.