Genetic diversity of Astragalus nitidiflorus, a critically endangered endemic of SE Spain, and implications for its conservation

Abstract

Abstract Inter-simple sequence repeats (ISSR) markers were used to assess the genetic diversity and population structure in five populations of Astragalus nitidiflorus , a critically endangered species endemic to southeast Spain. Eight primers amplified 78 bands with 40 (51.3%) being polymorphic. Statistical results indicated a low genetic diversity at the population and species level, with percentages of polymorphic bands (PPB) ranging from 28.2 to 37.2% (an average of 31.8%), and means of gene diversity ( H E ) of 0.129 and 0.171 respectively. The Shannon’s index (SI) ranged from 0.160 to 0.214 at the population level and was 0.260 at the species level. A low level of genetic differentiation among populations was detected, based on the Shannon’s information index (0.297), the coefficient of genetic differentiation between populations ( G ST = 0.2418) and AMOVA analysis ( Φ ST = 0.255). The estimated gene flow ( N m) was 0.789. The high genetic connectivity found among populations of A. nitidiflorus is an evidence of a recent habitat fragmentation. In addition, a bottleneck event in the past has been revealed, with a subsequent reduction of population size and a loss of genetic variation. Based on these results, the conservation strategy of A. nitidiflorus was proposed.