Chemical distances based on CHC analyses
New CHC extractions were performed following Peña-Carrillo et al. (2021a). We used the Bray-Curtis distances as dissimilarity measures to calculate chemical distances between the 156 examined specimens based on the relative abundances of the simplified chemical profile. This was obtained by summing the percentages of hydrocarbons with the same carbon-chain length by class (Peña-Carrillo et al. 2021a). We then calculated the chemical distance between populations (centroids) and used them to obtain a hierarchical cluster dendrogram using the program Primer 6 & Permanova + (Anderson 2017). We also performed Mantel tests based on Pearson’s product-moment correlation, running analyses with a maximum of 999 permutations to correlate chemical, genetic and geographic distances among the examined populations. Mantel tests were performed with the Vegan package (Oksanen et al. 2015) in R Studio (Version 3.5.2).