MASSIVE GENETIC INTROGRESSION AMONG ACONITUM (RANUNCULACEAE) SPECIES IN
A MOUNTAIN HYBRID ZONE
Abstract
HHybridization in Aconitum is a widespread phenomenon. However, the
introgression between the diploid and tetraploid species is rare. We
studied species of different ploidy in a mountain hybrid zone in the
Tatra Mts (West Carpathians). In this paper, we aimed to identify the
extent of introgressive hybridization using PCR-ISSR fingerprinting and
chloroplast DNA (cpDNA) sequencing. The diploid and tetraploid species
had different cpDNA haplotypes, and the triploid hybrid was stabilized
on the tetraploid level. ISSR markers showed the locally pervasive
introgression, but genetic introgressants were not morphologically
changed. Principal Coordinates Analysis, NeighborNet clustering, and
Bayesian inference showed close genetic links between individuals in the
same population but populations were significantly genetically
differentiated (FST = 0.129, p < 0.001). A genetic model of
introgression via the triploid bridge was proposed. Genetic
introgression does not seemingly pose a threat to species taxonomic
identity. The genetic differences between the same species in different
populations advocate for a web-of-life than a biological species
concept. Genetic introgressants in the isolated mountain populations
make each of them genetically unique.