Genetic diversity of the extremely rare Habenaria dentata and the rare Habenaria linearifolia (Orchidaceae) in South Korea: implications for population history and conservation

Background and aims – Since historical events often leave an indelible mark on levels of genetic diversity of plant populations, one may indirectly infer their evolutionary history with the help of current patterns of genetic diversity. The terrestrial orchid Habenaria dentata, an element of warm-temperate/subtropical vegetation, reaches its northernmost limits in the Korean Peninsula, and thus it is extremely rare there. As H. dentata was absent from the Peninsula during the Last Glacial Maximum (LGM), it is likely to be of post-glacial origin having arrived from either a single refugium or multiple refugia. However, its rare, temperate/boreal congener H. linearifolia might have persisted in situ in either macrorefugia or microrefugia on the Peninsula during the LGM.Methods – To test which hypothesis is most appropriate for each species, we investigated levels of allozyme-based (17 loci) genetic diversity and population genetic structure in the two only known populations of H. dentata and in 12 populations of H. linearifolia.Key results – No allozyme diversity was found in H. dentata (He = 0.000), whereas H. linearifolia exhibited low within-population variation (He = 0.060) and high among-population differentiation (FST = 0.237). We found little association between populations in relation to their geographic location; several populations presented individuals belonging to different clusters.Conclusions – Our results suggest that H. dentata likely originated from a single ancestral population (perhaps from southern Japan or southern China) through post-glacial dispersal, whereas H. linearifolia probably survived the LGM in situ in microrefugia situated at low to mid-elevated regions. We further suggest that separate conservation strategies for each species should be employed, given that the two taxa have different ecological and demographic traits and harbour different levels of genetic diversity.

Genetic diversity of two annual Salsola species (Chenopodiaceae) among habitat types in desert plant communities

Desert annual plant species are valuable pasture forage and sources for restoration of degraded pastures. Examining the impact of environmental stresses on genetic diversity and population structure can identify species populations suitable for habitat restoration. We examined allozyme diversity and population structure of two annual species, halo-xerophyte

Preliminary results on allozyme diversity and differentiation of Norway spruce (Picea abies (L.) Karst.) in Poland based on plus tree investigations

Genetic diversity and genetic differentiation among Polish populations of Norway spruce (<em>Picea abies</em> (L.) Karst.) were studied analyzing allozyme variation at 24 loci. Presented investigations based on 81 clones represented 6 populations from three different regions: Sudety Mts., Beskid Mts. and North-East Poland. On average, the expected heterozygosity was 0.134, 52.8% of loci were polymorphic, and the number of alleles per locus was 1.8. Our data confirm the hypothesis that a lower level of variation of <em>Picea abies</em> exists in central Europe, compared to other regions of its natural distribution. Relatively small allozyme differentiation among regions was observed (Fst =0.027, and Nei's genetic distances ranged from 0.005 to 0.008). Reasons for the low genetic differentiation observed between Southern and Northern populations are briefly discussed.

Low allozyme heterozygosity in North Pacific and Bering Sea populations of red king crab (Paralithodes camtschaticus): adaptive specialization, population bottleneck, or metapopulation structure?

Grant, W. S., Merkouris, S. E., Kruse, G. H., and Seeb, L. W. 2011. Low allozyme heterozygosity in North Pacific and Bering Sea populations of red king crab (Paralithodes camtschaticus): adaptive specialization, population bottleneck, or metapopulation structure? – ICES Journal of Marine Science, 68: . Populations of red king crab in the North Pacific and Bering Sea have declined in response to ocean-climate shifts and to harvesting. An understanding of how populations are geographically structured is important to the management of these depressed resources. Here, the Mendelian variability at 38 enzyme-encoding loci was surveyed in 27 samples (n = 2427) from 18 general locations. Sample heterozygosities were low, averaging HE = 0.015 among samples. Weak genetic structure was detected among three groups of populations, the Bering Sea, central Gulf of Alaska, and Southeast Alaska, but without significant isolation by distance among populations. A sample from Adak Island in the western Aleutians was genetically different from the remaining samples. The lack of differentiation among populations within regions may, in part, be due to post-glacial expansions and a lack of migration-drift equilibrium and to limited statistical power imposed by low levels of polymorphism. Departures from neutrality may reflect the effects of both selective and historical factors. The low allozyme diversity in red king crab may, in part, be attributable to adaptive specialization, background selection, ice-age population bottlenecks, or metapopulation dynamics in a climatically unstable North Pacific.