Low genetic variation in Amentotaxus formosana Li revealed by isozyme analysis and random amplified polymorphic DNA markers

Abstract

The objective of this research was to use random amplified polymorphic DNA (RAPD) and isozyme analysis to investigate genetic variation in narrowly distributed populations of Amentotaxus formosana Li. A total of 20 loci from 10 enzyme systems were analysed in 50 individual trees from each of the two natural populations. No isozyme variation was observed in the Tsatsayalai population. Phosphoglucose isomerase (Pgi-1) was the only polymorphic enzyme in the Tawu population, giving 5 per cent polymorphic loci with 0.008 expected heterozygosity. No genetic distance was found between these two populations using isozymes. Amentotaxus formosana demonstrated a high proportion of monomorphic RAPD fragments, about 79 per cent, for 20 arbitrary oligonucleotide primers. High similarity (0.994) was found between the Tawu and Tsatsayalai populations. RAPD markers provided further confirmation of the low levels of genetic variation in A. forinosana detected by isozyme analysis. The value of isozyme analysis was emphasized by the finding of the rare allele, Pgi-la, which was present only in the Tawu population. Based on the analysis of 110 individuals, representing 16 per cent of a native population, it was found that the younger tree category had a higher frequency of Pgi-la (0.125) than the older tree category (0.053), resulting in an expected heterozygosity of 0.250 and 0.105, respectively. It was inferred that the appearance of the Pgi-la allele could be the result of a mutation in the Tawu population and that selection is acting directly upon trees carrying this allele.

Chloroplast DNA phylogeography ofCunninghamia konishii(Cupressaceae), an endemic conifer of Taiwan

“…In contrast with the low level of genetic variation found in many relic species, for example, Amentotaxus fomosanus (Wang et al 1996), Archangiopteris itoi (ferns; Hsu et al 2000), and Chamaecyparis (Lin et al 1994) of Taiwan, North American Asclepias (Broyles 1998), and alpine Saxifraga (Bauert et al 1998), cpDNA variation was high in Cunninghamia. A total of 27 cpDNA haplotypes were detected among 41 individuals examined.…”

Low genetic diversity and significant population structuring in the relict Amentotaxus argotaenia complex (Taxaceae) based on ISSR fingerprinting

“…Based on this assumption, a high level of genetic diversity within species is thus expected in the A. argotaenia complex, especially in the widespread A. argotaenia. However, as revealed in A. formosana using RAPD and allozyme markers (Wang et al 1996), analyses of the ISSR fingerprints based on various statistics revealed low levels of genetic diversity within all populations of the A. argotaenia complex. Shannon indices in the 15 Amentotaxus populations ranged from 0.0263 to 0.0939 (Table 2).…”

“…Accelerating genetic drift that leads to stochastic loss of genetic polymorphisms can counteract the effect of outcrossing mating system (Chiang et al 2003). A recent investigation based on allozymes and RAPD fingerprinting reveals very low diversity in two relic populations of A. formosana in Taiwan (Wang et al 1996). Even so, to date, the population genetics of mainland species still remains unknown.…”

Brief communication. Population genetics of geographically restricted and widespread species of Myrica (Myricaceae)

“…Even though rare, M. adenophora maintains higher levels of genetic diversity than many rare tree species in Taiwan, such as Amentotaxus formosana (H e ϭ 0.004; Wang et al 1996), Bretschmeidera sinensis (H e ϭ 0.062; Huang 1994), and Rhododendron kanehirai (H e ϭ 0.068; Huang et al 1995). This pattern may be due to the relationships between the specific progenitor-derivative species pairs.…”