Figure 1.
Phenotypic variability, genetic diversity and predation pressure measured in Ranitomeya imitator for the study sites.
(A) Topographic profile of the study system with the study sites along the 18 km transect. (B) Phenotypic variation within sites of both aposematic dorsal coloration and pattern measured using the Shannon diversity index. (C) Neutral genetic variation estimated from nine nuclear microsatellites loci in terms of expected heterozygosity and mean number of alleles per loci, and their associated standard deviation. (D) Avian predation frequency on each aposematic signal in each site. Within sites Freeman-Tukey deviates identify which model phenotype suffered significantly (*) more (+) or less (−) predation attempts and are indicated above the bars, and the sample size is specified below.
Figure 2.
Phenotypic distribution and genetic differentiation measured in Ranitomeya imitator for the study sites.
(A) Frequency distribution of the different aposematic phenotypic coloration and dorsal patterns found among individuals in the four study sites. (B) Individual assignment among K = 2 clusters using STRUCTURE and (C) the hierarchical partioning of genetic variance between population groups estimated from nuclear microsatellites and mitochondrial control region; * indicates a level of significance of p<0.05. (D) Minimum spanning tree for mitochondrial control region haplotypes detected in this study. Each box refers to a distinct haplotype and the size represents its relative abundance.
Figure 3.
Schematic representation of the diversification process of aposematic signals in R. imitator.
The colored areas represent zones of high predation selecting distinct phenotypes and the grey area corresponds to a migration barrier for R. imitator. Individuals originating from the monomorphic yellow striped lowland populations (right) colonized (arrows) the transient zone (white area). Under the lowered predation pressure prevalent in these elevations, aposematic signals diversified due to genetic drift. Among the novel signals, the green reticulated phenotype which is recognized by predators (left) enabled the further colonization of the system, while other signals are highly counter selected (X). Below the figure is a schematic representation of the relative intensity of selection compared to genetic drift.