Contrasting population genetic structure of two sympatric species of Anthurium (Araceae) along elevation in an Andean mountain forest

The topography of the tropical Andean forest is steep, resulting in physical conditions that change with the elevation, thus driving a high turnover of insect pollinator species over short distances, which may lead to localized gene dispersal, promoting genetic divergence between plant populations distributed along the elevation gradient. In this study, we characterized the population genetic structure of Anthurium caucanum and A. panduriforme, two closely related species that coexist along the elevation gradient in the Andean forest but differ in inflorescence size and abundance of flower visitors. The sampling of both species covered seven elevation bands, from 2,200 to 2,900 MASL. Five microsatellite loci were used to genotype the sampled individuals. Our results indicated that heterozygosity was high for both species. Genotypic richness was significantly lower for A. caucanum (G/N = 0.45) compared with A. panduriforme (G/N = 0.88), while population differentiation was strong for A. caucanum (Fst = 0.23) but low for A. panduriforme (Fst = 0.03). Assignment analysis suggested a low rate of immigration events for A. caucanum populations and a high gene flow between A. panduriforme populations. Based on the seed production of bagged inflorescences, A. caucanum demonstrated the ability to self‐pollinate, while A. panduriforme was considered self‐incompatible. In addition, genotypic richness decreased with elevation for A. caucanum. In summary, the contrasting population genetic structure of the two Anthurium species along the elevation gradient appear to be the result of different gene flow rates, mating systems, and life‐history traits, such as clonal growth, flowering phenology, and density. in Spanish is available with online material. Resumen La topografía de altas pendientes en los bosques Andinos del trópico puede originar cambios en las condiciones físicas a través de la elevación causando una alta tasa de recambio de las especies de insectos polinizadores a distancias cortas y una reducción en la diversidad a alta elevación, lo cual puede conducir a dispersión localizada de genes promoviendo divergencia genética entre poblaciones de plantas distribuidas a lo largo del gradiente. En este estudio, se caracterizó la estructura genética de las poblaciones de Anthurium caucanum y A. panduriforme, dos especies cercanamente relacionadas que coexisten a lo largo de un gradiente de elevación en un bosque Andino, pero con tamaño de las inflorescencias y abund