High genetic diversity in the only known population of Aechmea tuitensis (Bromeliaceae)

Abstract

Aechmea tuitensis (P. Magaña and E. Lott) is a narrow endemic species from Mexico. Only one population has been reported. We studied the genetic variation and structure, and clonal diversity of this rare bromeliad by using starch gel electrophoresis. Six enzyme systems encoded by nine gene loci were resolved in nine subpopulations. The percentage of polymorphic loci was high (77.8%). Mean expected heterozygosity for the population was 0.12. All loci except CPX-1 were in Hardy–Weinberg equilibrium. Genetic diversity was substantially larger within subpopulations (mean F_is = 0.631) than between them (F_st = 0.196). We detected 33 genetically distinguishable clones from 109 plants (ramets) sampled. One clone had a frequency of 32.1%, others showed frequencies ranging from 1.8 to 9.2%, and 19% of the total samples were unique multilocus genotypes. Aechmea tuitensis exhibits high genetic diversity even though it has an extremely narrow distribution. Our results also suggest that the effect of genetic drift on genetic structure in A. tuitensis might be counteracted by the influence of vegetative reproduction.