Genetic diversity within and among populations of the endangered species Taxus fuana (Taxaceae) from Pakistan and implications for its conservation.

摘要

The West Himalayan yew, Taxus fuana Nan Li & R.R. Mill (Taxaceae), is an endangered species endemic to the Western Himalayas. An investigation of the genetic diversity of wild populations of T. fuana in Pakistan was undertaken. The genetic diversity and genetic structure was quantified using random amplified polymorphic DNA (RAPD) variation in 219 individuals of the 10 populations. Of the 32 universal primers screened 16 produced highly reproducible, clear RAPD bands. Using these primers, 193 discernible DNA fragments were generated, of which 164 (84.97%) were polymorphic. The statistical results indicated that there was a relatively low genetic diversity within populations (with percentages of polymorphic bands, PPB, ranging from 29.53 to 50.26%, with an average of 38.34% and a Nei's genetic diversity index (HE) of 0.1165), and a high genetic differentiation among populations (GST=0.5842, Phi ST=0.5685) within these populations. The gene flow (Nm) was low with only 0.3558. The distribution of genetic diversity revealed among the wild populations of T. fuana in Pakistan may result from their evolutionary history including habitat fragmentation, genetic drift combined with limited gene flow. The results are unexpected for an outcrossing, wind-pollinated and long-lived woody species. Based on these findings, conservation concerns are discussed together with possible strategies for implementing in situ and ex situ conservation.