Addressing the challenges of biodiversity conservation problem demands the investigation of the genetic variability of a rare, endangered species, such as an endemic of the Kamchatka Peninsula Abies gracilis Kom. Single population of the fir occupies an area of about 20 hectares on the southeastern part of the peninsula, nearly 1000 km away from the other fir species ranges. Aim of this study was to clear up the taxonomic status of A. gracilis, to study the level of genetic diversity and to shed light on the demographic history and origin of this fir using three types of genetic markers.
A needles and buds from twenty five fir trees were collected in the grove within the Kronotzky State Reserve. 17 populations of the geographically nearest fir species A. nephrolepis, A. sachalinensis and 38 populations of the A. sibirica with sample size 24-50 trees were taken for the comparison. Eight enzyme systems and 11 loci were used in allozyme analysis.
In A. gracilis population the heterozygosity level was not reduced (Íî=0.102, Íå=0.135) in spite of relatively low proportion of polymorphic loci (Ð100=36.4%), and allele number (À=1.4). Highest heterozygote deficiency among the investigated Abies populations observed in A. gracilis (FIS=0.248, P=0.0292) indicates certain inbreeding supposedly due to selfing.
Genetic distances (D, Nei, 1978) between A. gracilis and the rest of Abies correspond to species rank differences and indicate more similarity of A. gracilis with À. sachalinensis – A. nephrolepis complex than with the A. sibirica. On the same time A. nephrolepis and A. sachalinensis are the closest relatives to A. gracilis by allozyme date. All allozyme alleles observed in the latter are present in the former species. A. gracilis is somewhat more similar to A. nephrolepis (mean D =0.072) than to A. sachalinensis (mean D =0.101).
According to study of the mtDNA variation in firs of the Far East, common mitotype “n” is fixed in A. gracilis, in mainland and in northern Sakhalin while another haplotype “s” is distributed in Southern Sakhalin and Kunashir suggesting the continental origin of the Kamchatka population.
In chloroplast genome the variation of two highly polymorphic chloroplast microsatellite loci Pt71936 and Pt30204 (Vendramin et al., 1996) was investigated. Only one chloroplast haplotype was found in A. gracilis population. Low level of genetic variation in A. gracilis could be explained by population bottleneck due to LGM climate conditions or/and volcanoes activity delaying the forest vegetation development on the eastern coast of the peninsula in Holocene. It seems that the bottleneck has removed the cpSSR variation, but it was not sufficient to eliminate the allozyme variation perhaps due to bigger effective population size, specific to nuclear genes in comparison with cytoplasmic ones.
Note. Abstracts are published in author's edition