Population differentiation and phylogeography of Hygrophila pogonocalyx based on RAPDs fingerprints

Abstract

Genetic variation of the endangered species, Hygrophila pogonocalyx Hayata (Acanthaceae), was estimated based on RAPD fingerprints. According to the criteria of the International Union for Conservation of Nature and Nature Resources, H. pogonocalyx is on the Red List Category due to its endangered status. Entomophilous plants of H. pogonocalyx are mostly pollinated by honeybees. Gene flow between populations is constrained by the migratory capacity of the pollinators. A survey based on RAPD fingerprinting using 50 random primers revealed the distribution of genetic variation following an “isolation by distance” model. A hierarchical AMOVA analyses indicated significant differentiation between geographical regions ( Φ ct=0.934; P=0.048), among populations ( Φ st=0.945; P<0.001), and among populations within region ( Φ sc=0.169; P<0.001). The differentiation between geographic populations may be ascribed to a long isolation since the formation of the Central Mountain Range 1 million years ago. In contrast to low levels of genetic variation in many endangered species, some genetic processes avoiding selfing may have evolved in H. pogonocalyx. Somatic mutation also possibly contributed to the variability maintenance within populations with limited size.