3.3 Population structure
A comparison of BIC values from the genus-level DAPC analyses suggested
a total of five genetic clusters, with two populations in T.
blandingii and three in T. pulverulenta , matching the clades
identified in the phylogenetic analyses (Fig. S3). Our admixture-based
method, LEA, identified two distinct genetic clusters at the genus
level, corresponding to the two Toxicodryas species, and the same
two populations for T. blandingii and three populations forT. pulverulenta as suggested by DAPC (Fig. 4). A low amount of
admixture was identified in the Cameroonian sample of T.
blandingii , and varying levels of admixture were suggested for the
Gabonese samples of T. pulverulenta (Fig. 4). The population
assignment of individuals between the two clustering methods was
identical; however, admixture between populations was not detected by
DAPC. Similarly, STRUCTURE suggested two populations at the genus level,
and two in T. blandingii , but combined the Central African clades
and suggested two populations, instead of three, for T.
pulverulenta . Three populations were supported as the second highest ΔK
and showed identical admixture proportions to those from LEA. We used
five populations for our remaining analyses because multivariate-based
analyses such as LEA and DAPC do not make assumptions about
Hardy-Weinberg equilibrium and may be preferable over Bayesian methods
such as STRUCTURE when sample sizes are small or uneven (Puechmaille,
2016).