Genetic diversity of fragmented populations of<Emphasis Type="Italic"> Polygala reinii</Emphasis> (Polygalaceae), a perennial herb endemic to Japan

Genetic variation at 10 allozyme loci was analyzed in 14 populations of Polygala reinii (Polygalaceae), a perennial herb endemic to central Honshu, Japan, with a fragmented geographical distribution. The levels of genetic variation within species (P=80.0, A=3.10, H_E=0.303) and within populations (P=42.1, A=1.61, H_E=0.163) were considerably higher than the mean for other endemic plants or short-lived perennial herbs. Genetic differentiation among populations was also high (G_ST=0.404). The genetic distance phenogram tended to show a clustering of the populations reflecting the fragmentation of the species range. A principal component analysis revealed the same tendency, as well as three groupings of populations in the Tokai district, on the Kii Peninsula and in the northern Kinki district. A negative correlation was obtained between the levels of gene flow and geographical distance among the populations (r=–0.745, P<0.0001). These results indicated limited gene flow among populations in P. reinii, presumably due to the geographical isolation accompanying the fragmented distribution. On the other hand, the geographical differentiation between the Japan Sea and Pacific Ocean sides was found in P. reinii, suggesting the influence of postglacial migration on the establishment of the genetic structure of this species.     

Genetic diversity in <Emphasis Type="Italic">Delphinium staphisagria</Emphasis> (Ranunculaceae), a rare Mediterranean dysploid larkspur with medicinal uses

Delphinium staphisagria is an endemic annual or biennial herb from the Mediterranean Basin, widely distributed in isolated populations of variable size. We evaluated the allozyme diversity of 31 populations along its distribution range via starch gel electrophoresis, assaying 12 enzyme systems and scoring 17 loci. The low levels of genetic variability detected (A = 11.8, A _p = 1.6, H _o = 0.026, H _e = 0.057), are discussed in relation to the life-history traits of the species, such as short life-span, selfing or gravity seed dispersion. Other factors influencing genetic diversity, such as evolutionary history and spreading are also considered. Due to its historical medicinal uses, this plant has probably become widespread in the Mediterranean area. Human-mediated distribution could have promoted few migrant genotypes, recent founder events and long distance dispersal. These events would explain the genetic homogeneity found within and among populations, as well as the absence of a clear biogeographic structure. The limited genetic variability, the high genetic similarity among populations and the dysploidy of this species make it worthy of conservation. Management strategies are proposed mainly to preserve its genetic pool.     

Grain protein variability among populations of wild barley (Hordeum spontaneum C. Koch.) from Jordan

Summary Protein content, kernel weight, and genetic diversity in the storage protein hordein, encoded by the Hor 1 and Hor 2 loci, were assessed in 12 populations of wild barley (Hordeum spontaneum C. Koch.) collected from central, peripheral, and marginal areas of its distribution in Jordan. Protein content ranged from 106.3 to 239.1 g kg^-1, and kernel weight ranged from 21.17 to 31.8 mg. Populations with high protein content and heavy kernels have been identified. Electrophoretic analysis of the storage protein hordein showed that the two hordein loci, Hor 1 and Hor 2, are highly polymorphic, having 34 and 38 alleles, respectively. Polymorphism (H_e) was highest in central populations (H_e Hor 1=0.859, H_e Hor 2=0.782), intermediate in peripheral populations (H_e Hor 1=0.566, H_e Hor 2=0.509), and lowest in marginal populations (H_e Hor 1=0.392, H_e Hor 2=0.349). Geographical distances between populations were not indicative of Nei's genetic similarity (NI). NI values averaged 0.209 and ranged from 0.0 to 0.83, supporting the hypothesis of an island population model for the species. The high proportion of allelic diversity, apportioned among populations for Hor 1 (0.584) and Hor 2 (0.495) loci, indicates that these natural populations are a rich reserve of genetic variability for protein. This variability is readily exploitable in breeding.     

Genetic structure of Polytrichum formosum in relation to the breeding system as revealed by microsatellites

Microsatellite variation was determined for three Danish and three Dutch populations of the haploid moss species Polytrichum formosum to gain insight into the relative importance of sexual vs. asexual reproduction for the amount and structure of genetic variation. In general, low levels of microsatellite variation were observed within this species. Even when estimated for polymorphic loci only, the levels of microsatellite variability (P=90.6, A=4.3 and H_S=0.468) within populations were on average lower than those reported for most other plant species. In contrast, genotypic diversity was high within each of the examined populations, indicating that sexual reproduction is a very important determinant of the genetic structure of P. formosum within populations. In agreement with previous findings for allozyme data, no significant genetic differentiation (F_ST=0.028, R_ST=0.015) was observed neither between populations nor between regions approximately 450 km apart (Denmark vs. the Netherlands). These low levels of population differentiation observed for both types of genetic markers are probably best explained by a high level of effective spore dispersal (gene flow) between populations. Therefore, also on a large geographical scale sexual reproduction is the most important determinant of the genetic structure of P. formosum, despite the high potential to reproduce clonally.     

Comparative analysis of genetic structure in natural populations of two <Emphasis Type="Italic">Arabidopsis</Emphasis> species with different degree of panmixia

Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P _99% = 62.50%; H _exp = 0.169) than the populations of A. thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P _99% = 42.27%; H _exp = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average D _N = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.     

Demography, and genetic and morphological variability of the endangered Sophronitis sincorana (Orchidaceae) in the Chapada Diamantina, Brazil

We carried out a demographic study and evaluated the genetic and morphological variability in five populations of the endangered Sophronitis sincorana (Orchidaceae) endemic to Northeastern Brazil, based on allozyme and morphometric analyses. Plant density was approximately 0.5 plants/m², and the projected total number of plants was approximately 50,000 individuals. However, fruit set and recruitment of individuals are rare. The genetic variability was very high in all populations (P = 100, A = 3.0−3.5, H _e = 0.33−0.48), and all populations presented similar values of morphological variability. Low genetic and morphological structuring were found in the species (F _ST = 0.053, A_MRPP = 0.018). The elevated coefficient of endogamy encountered in populations of S. sincorana indicates the occurrence of structuring within the populations. The lack of correlation between morphological and genetic variation in this species indicates that none of the markers examined should be used separately for either conservation purposes.     

Polyploid origin,genetic diversity and population structure in the tetraploid sea lavender <Emphasis Type="Italic">Limonium narbonense</Emphasis> Miller (Plumbaginaceae) from eastern Spain

Limonium narbonense Miller is a fertile tetraploid species with a sporophytic self-incompatibility system. This sea lavender is found in coastal salt marshes which have been under intense human pressure during the past decades resulting in significant habitat fragmentation. Eleven microsatellite loci specifically designed for this species were amplified in 135 individuals from five populations. These markers were used to investigate the polyploid nature, the levels of genetic diversity and population structure in this species. L. narbonense showed high levels of genetic diversity (A = 7.82, P = 100% H _T = 0.446), consistent with its likely autotetraploid origin revealed in this study and obligate outcrossing breeding system. Inbreeding (F _IS) values were low in the three southern populations (mean F _IS = 0.062), and higher in the northern populations (mean F _IS = 0.184). Bayesian analysis of population structure revealed that populations could be grouped into two genetic clusters, one including three southern populations and the other the two northernmost ones. Individuals from the two northernmost populations showed higher admixture of the two genetic clusters than individuals from the three southern ones. A thorough analysis of microsatellite electrophoretic patterns suggests an autotetraploid origin for L. narbonense. The genetic structure revealed in this study is attributed to a recent migration from the southern area. This result suggests a net gene flow from the south to the north, likely facilitated by migratory movements of birds visiting the temporary flooded ponds occupied by L. narbonense.     

Genetic variability of Siberian fir <Emphasis Type="Italic">Abies sibirica</Emphasis> Ledeb. inferred from AFLP markers

Genetic variability of AFLP markers was studied in 20 populations of Siberian fir (Abies sibirica, Pinaceae) and in two populations of Far-Eastern species Manchurian fir A. nephrolepis and Sakhalin fir A. sachalinensis each. Four pairs of selective primers were used. In total, 168 samples from three fir species were genotyped for 117 polymorphic loci. According to the AMOVA results, the variability proportion characterizing the differences among three Abies species was several times higher (F _CT = 0.53) than that acounting for population differences within the species (F _SC = 0.125). Differentiation of the A. sibirica populations based on AFLP markers exceeded 14% (F _ST = 0.141). Significant correlation between the genetic distances calculated from the AFLP data and the geographic distances between populations was found. The results of AFLP variability analysis supported and supplemented the conclusions inferred previously from allozyme and cpSSR data: several genetically similar geographic groups of Siberian fir were identified. These groups differ both in allele frequencies and in the levels of genetic variation.     

Genetic diversities of four little-known species of Malesherbia (Malesherbiaceae) endemic to the arid inter-Andean valleys of Peru

Few studies of genetic variation have been conducted on plants of the Pacific coastal desert and neighboring Andes of Peru, although the region has many endemic taxa. Enzyme electrophoresis was employed to examine allozyme diversities of four species of the family Malesher-biaceae, an endemic to the arid Andes and coastal desert. One population ofMalesherbia splendens and two ofM. tubulosa, both endemics of the department of Lima, one population ofM. weberbaueri var.weberbaueri, an endemic of the Andean department Huancavélica, and the two Lima populations ofM. scarlatiflora were studied. Fifteen loci were examined for all populations and an additional seven loci were resolved forM. weberbaueri andM. splendens. Malesherbia splendens, which is known from three populations, has a low mean number of alleles per locus (A), proportion of polymorphic loci (P), and expected heterozygosity (H_s) (A=1.214, P=0.214, H_s=0.057).Malesherbia weberbaueri (A=1.231, P=0.154, H_s=0.079) andM. scarlatiflora (A=1.364, P=0.273, H_t=0.083) both have average expected heterozygosities and relatively low mean numbers of alleles per locus and proportions of polymorphic loci. InM. tubulosa, all measures of genetic diversity are high in comparison with other endemics (A=1.818, P=0.364, H_t=0.206).Malesherbia tubulosa has high interpopulation differentiation, whereasM. scarlatiflora has low among-population diversity. The relatively low allozyme diversities, restricted habitats, narrow ranges ofM. splendens andM. weberbaueri, and the morphological similarities of all four species suggest that they evolved recently by founder events. Greater allozyme diversities inM. tubulosa could be attributable to its maintenance of larger populations in a greater variety of habitats.     

Isolation by distance and a chromosomal cline in the Cayapa cytospecies of <Emphasis Type="Italic">Simulium exiguum</Emphasis>, the vector of human onchocerciasis in Ecuador

The population genetic structure of the Cayapa cytospecies of Simulium exiguum, the vector of onchocerciasis, was analysed using allozyme frequency and chromosomal inversion polymorphism data from 6 and 15 populations respectively, collected in Ecuador. Eight allozyme loci were scored. No unique allozyme markers were found enabling us to identify biting adults of the vector from the non-vector Bucay cytotype. Mannose-phosphate isomerase (Mpi) contributed largely to the significant heterogeneity in gene frequency among populations of the Cayapa cytospecies and also to the overall population structuring (F_ST=0.015 ± 0.014) which fitted the isolation by distance model. However, heterozygote deficits were recorded for Mpi in four of the six populations, which could indicate that selection is acting at this locus but this hypothesis will require further convincing evidence. Furthermore the significant population structuring of allozymes was not evident when Mpi was omitted from the analysis. All inversion polymorphisms (IIS-B, IIS-F, IIL-A and IIL-B) were in Hardy-Weinberg equilibrium, showed significant heterogeneity between populations and revealed the occurrence of an altitudinal cline in inversion IIS-B frequency. The inversion polymorphisms revealed a significant degree of population structuring (F_ST=0.083 ± 0.027), which can be explained by the isolation by distance model. A UPGMA cluster analysis revealed the relatively remote, high altitude Rio Mira populations to be the most genetically distinct.     

Evolutionary implications of allozyme and RAPD variation in diploid populations of dioecious buffalograss Buchloë dactyloides

Buffalograss, Buchloë dactyloides, is widely distributed throughout the Great Plains of North America, where it is an important species for rangeland forage and soil conservation. The species consists of two widespread polyploid races, with narrowly endemic diploid populations known from two regions: central Mexico and Gulf Coast Texas. We describe and compare the patterns of allozyme and RAPD variation in the two diploid races, using a set of 48 individuals from Texas and Mexico (four population samples of 12 individuals each). Twelve of 22 allozyme loci were polymorphic, exhibiting 35 alleles, while seven 10-mer RAPD primers revealed 98 polymorphic bands. Strong regional differences were detected in the extent of allozyme polymorphism: Mexican populations exhibited more internal gene diversity (H_e= 0.20, 0.19) than did the Texan populations (H_e= 0.08, 0.06), although the number of RAPD bands in Texas (n= 62) was only marginally smaller than in Mexico (n= 68). F-statistics for the allozyme data, averaged over loci, revealed strong regional differentiation (mean F_RT=+ 0.30), as well as some differentiation among populations within regions (mean F_PR=+ 0.09). In order to describe and compare the partitioning of genetic variation for multiple allozyme and RAPD loci, we performed an Analysis of Molecular Variance (AMOVA). AMOVA for both allozyme and RAPD data revealed similar qualitative patterns: large regional differences and smaller (but significant) population differences within regions. RAPDs revealed greater variation among regions (58.4% of total variance) than allozymes (45.2%), but less variation among individuals within populations (31.9% for RAPDs vs. 45.2% for allozymes); the proportion of genetic variance among populations within regions was similar (9.7% for RAPDs vs. 9.6% for allozymes). Despite this large-scale concordance of allozyme and RAPD variation patterns, multiple correlation Mantel techniques revealed that the correlations were low on an individual by individual basis. Our findings of strong regional differences among the diploid races will facilitate further study of polyploid evolution in buffalograss.     

Coarse-grained population structure in Central European sculpin (Cottus gobio L.): secondary contact or ongoing genetic drift?

Population genetic affinities of 261 European sculpins Cottus gobio L. across the Rhenanian-Danubian and the Rhenanian-Rhónian watersheds were assessed by horizontal agarose-gel electrophoresis of up to 20 allozyme systems (encoded by 29 genetic loci). Polymorphism P_mean= 0.0689 (range: 0.000-0.1379), and heterozygosity H_e(mean)= 0.0167 (range: 0.000-0.0507) indicated low genetic variability within local stocks from single streams. Significant genetic distances D_mean= 0.1917 ± 0.0336 (D_max= 0.2407), based on differential fixation at 3–6 loci (Acp-1**, Pgdh**, Fh**, Est-1**, Gpi-2**, and Pgm-1**) distinguished populations from the Neckar catchment basin from those of the Hochhrein-Oberrhein and Danube basins. Differential fixation of alleles and pronounced genetic distances also separated sculpins of the Rh6nian tributary Doubs from Neckarian populations (D_men= 0.2131 ± 0.0033; Ah**, Acp-1**, Fh**), of the Doubs from the Danube (D_mean= 0.2177 ± 0.0028; Gpi-2**, Pgm-1**, Pgdh**, Ah**), and of the Doubs from the Hochrhein-Oberrhein (D_mean= 0.1780; Pgm-1**, Pgdh**, Ah**). Genetic distances between streams within these drainages proved low (Neckar: D_men= 0.0047 ± 0.0014, Danube: D_mean= 0.026 ± 0.0179, Rhine: D_mean= 0.0308). Screening of another 16 small-size samples consisting of 55 sculpins for nine diagnostic loci (Aat-2**, Acp-1**, Acp-2**, Ah**, Est-1**, Fh**, Gpi-2**, Pgdh** and Pgm-1**) confirmed the genetic homogeneity of sculpins within the Danubian and Neckarian drainage systems, but Neckarian sculpins were similar to those from the river Main. Populations from Hochrhein-Oberrhein resembled the Danubian stock but contained a decreasing frequency of ‘Neckarian’ markers when approaching the Danubian region. The genetic divergence between Neckarian, Danubian and Rhdnian sculpins suggests the existence of hitherto neglected taxa of anteglacial divergence.     

Genetic diversity of the endangered Chinese endemic herb Primulina tabacum (Gesneriaceae) revealed by amplified fragment length polymorphism (AFLP)

Primulina tabacum Hance, is a critically endangered perennial endemic to limestone area in South China. Genetic variability within and among four extant populations of this species was assessed using AFLP markers. We expected a low genetic diversity level of this narrowly distributed species, but our results revealed that a high level of genetic diversity remains, both at population level (55.5% of markers polymorphic, H _E = 0.220, I _S = 0.321), and at species level (P = 85.6% of markers polymorphic, H _E = 0.339, I _S = 0.495), probably resulting from its refugial history and/or breeding system. High levels of genetic differentiation among populations was apparent based on Nei’s genetic diversity analysis (G _st=0.350). The restricted gene flow between populations is a potential reason for the high genetic differentiation. The population genetic diversity of P. tabacum revealed here has clear implications for conservation and management. To maintain present levels of genetic diversity, in situ conservation of all populations is necessary.     

The diversity of chloroplast microsatellite loci in Siberian fir (Abies sibirica Ledeb.) and two Far East fir species A. nephrolepis (Trautv.) Maxim. and A. sachalinensis Fr. Schmidt

The genetic variability in 29 populations of Abies sibirica, three of A. nephrolepis, and seven of A. sachalinensis was studied using SSR markers of chloroplast DNA. Among ten primer pairs examined, pairs Pt71936 and Pt30204 gave stable amplification and polymorphic products (with nine and fourteen alleles, respectively). Totally, 70 haplotypes were found, 43 in A. sibirica, 49 in A. sachalinensis, and 31 in A. nephrolepis. The highest values of genetic diversity parameters were observed in A. sachalinensis, and the lowest in A. sibirica. The Siberian fir differs from Far East species by the uneven multimodal frequency distributions of allele length in both cpSSR loci, which is explained by the presence of few separated from each other dominating haplotypes. This fact indicates that A. sibirica and the Far East species have different demographic histories. In A. sibirica, the proportion of diversity between populations in the total genetic diversity, calculated taking into account the differences between haplotypes (R _ST) was 8.34 and 4.42% without accounting for haplotypes differences (R _ST > G _ST, P = 0.01). The pairwise G _ST correlate significantly with geographic distances between the populations A. sibirica and with genetic distances D calculated from allozyme data. No such correlations were found with the R _ST parameter. The results of cpSSR variability analysis strongly support the conclusions inferred from allozyme data: several geographic groups of comparatively genetically close populations are identified, which may be explained by the history of colonization of the present-day Siberian fir range. Original Russian Text ? S.A. Semerikova, V.L. Semerikov, 2007, published in Genetika, 2007, Vol. 43, No. 12, pp. 1637–1646.     

Population Genetic Structure of Two Columnar Cacti with a Patchy Distribution in Eastern Brazil

The genetic variability and population genetic structure of six populations of Praecereus euchlorus and Pilosocereus machrisii were investigated. The genetic variability in single populations of Pilosocereus vilaboensis, Pilosocereus aureispinus, and Facheiroa squamosa was also examined. All of these cacti species have a patchy geographic distribution in which they are restricted to small areas of xeric habitats in eastern Brazil. An analysis of genetic structure was used to gain insights into the historical mechanisms responsible for the patchy distribution of P. euchlorus and P. machrisii. High genetic variability was found at the populational level in all species (P=58.9–92.8%, A_p=2.34–3.33, H_e=0.266–0.401), and did not support our expectations of low variability based on the small population size. Substantial inbreeding was detected within populations (F_IS=0.370–0.623). In agreement with their insular distribution patterns, P. euchlorus and P. machrisii had a high genetic differentiation (F_ST=0.484 and F_ST=0.281, respectively), with no evidence of isolation by distance. Accordingly, estimates of gene flow (N_m) calculated from F_ST and private alleles were below the level of N_m=1 in P. machrisii and P. euchlorus. These results favored historical fragmentation as the mechanism responsible for the patchy distribution of these two species. The genetic distance between P. machrisii and P. vilaboensis was not compatible with their taxonomic distinction, indicating a possible local speciation event in this genus, or the occurrence of introgression events.     

An AFLP-based survey of genetic diversity and relationships of major farmed cultivars and geographically isolated wild populations of <Emphasis Type="Italic">Saccharina japonica</Emphasis> (Phaeophyta) along the northwest coasts of the Pacific

The genetic diversity and relationships of six representative cultivars and six geographically isolated wild populations of Saccharina japonica along the northwest coasts of the Pacific Ocean were investigated using AFLP markers. A total of 547 bands were generated across all samples by ten primer combinations. At the cultivar or population level, the percentage of polymorphic loci (P), gene diversity (H), and Shannon’s information index (I) was highest in Dalian population (P 59.05%; H 0.2057; I 0.3062) and lowest in Lianjiang cultivar (P 9.87%; H 0.0331; I 0.0497). At the species level, P, H, and I were 85.01%, 0.1948, and 0.3096, respectively. Unique bands were detected in all the six wild populations, with Dalian being the most. In comparison, only Yanza cultivar possessed one unique band. The G _ST value was 0.6226 and the gene flow (N _m ) was 0.1515, indicating strong genetic differentiation among cultivars and populations. Two UMPGA dendrograms were constructed based on the Dice similarity coefficients among individuals and on genetic distances among cultivars and populations, which generally revealed three major clades corresponding to three countries. Analysis of molecular variance revealed that a larger proportion (60.21%) of the total genetic variation was attributable to differences among cultivars and populations. The Mantel test suggested that genetic differentiation was positively correlated with geographic distance (r = 0.7962, P = 0.011) in the six wild populations, agreeing with the isolation by distance model. On the whole, low to moderate genetic diversity within cultivars and populations (except Dalian population) and high genetic differentiation among cultivars and populations were detected.     

The ‘paradigm of extremes’: extremely low genetic diversity in an extremely narrow endemic species, Coristospermum huteri (Umbelliferae)

Low levels of genetic diversity in endemic species are generally attributable to the small size of their populations. This lack of genetic variability will, predictably, be more evident in those species that occur in only one or a very few localities with a total population consisting of a few dozen individuals, or sometimes fewer (i.e. ‘extremely narrow endemics’, ENEs). We used allozyme electrophoresis to survey the genetic variability of Coristospermum huteri, an endemic species from the island of Majorca (Balearic Islands, W. Mediterranean Basin) with a single natural population of about 100 individuals. As expected, allozyme variability was virtually nil for this species (P = 8.3 %, A = 1.08, H _e = 0.022), which seems to be a general rule for ENEs (mean H _e = 0.057). A founder effect associated with a dispersal event from the continent is probably behind the lack of genetic diversity in this highly threatened species. Preservation of the mountain summit where the plant is found (Puig Major) is essential for the survival of C. huteri, and would also guarantee the conservation of other ENEs and rare and threatened species.     

Genetic Diversity and Geographical Differentiation of <Emphasis Type="Italic">Desmodium triflorum</Emphasis> (L.) DC. in South China Revealed by AFLP Markers

High levels of genetic variation enable species to adapt to changing environments and provide plant breeders with the raw materials necessary for artificial selection. In the present study, six AFLP primer pairs were used to assess the genetic diversity of Desmodium triflorum (L.) DC. from 12 populations in South China. A high percentage of polymorphic loci (P = 76.16%) and high total gene diversity (H _T = 0.310) were found, indicating that the genetic diversity of D. triflorum is high at the species level. Genetic diversity was also relatively high at the population level (P = 55.85%, H _e = 0.230). The coefficient of gene differentiation among populations (G _ST) was 0.255, indicating that while most genetic diversity resided within populations, there was also considerable differentiation among populations. AMOVA also indicated 24.29% of the total variation to be partitioned among populations (Φ_ST = 0.243). UPGMA clustering analysis based on genetic distances showed that the 12 populations could be separated into three subgroups: an eastern, a western, and a central-southern subgroup. However, a Mantel test revealed no significant correlation (r = 0.286, p = 0.983) between the geographical distances and genetic distances separating these populations; mountain barriers to gene flow and human disturbance may have confounded these correlations. The present study has provided some fundamental genetic data that will be of use in the exploitation of D. triflorum.     

Genetic variability of natural populations and man-made stands of common pine (Pinus sylvestris L.) in Kremenets Hills and Maloe Polese

Comparative analysis of 19 allozyme loci of Pinus sylvestris L was performed on three relic populations and six uneven-aged man-made stands to evaluate genetic variability of common pine in Kremenets Hills and Maloye Polesye. Low heterozygosity was characteristic of all natural populations and of four forest stands (H_o = 0.182–0.205), whereas in two forest stands the level of heterozygosity was noticeably higher (H_o = 0.245–0.300). Both allelic and genotypic variability of natural populations was reproducible in the man-made forest. However, the genetic distance between forest stands and natural populations was considerably higher than that among three natural populations (D_Nav = 0.014 and D_Nav = 0.003, respectively).     

Conservation of long-lived perennial forest herbs in an urban context: <Emphasis Type="Italic">Primula elatior</Emphasis> as study case

Urban forests are generally fragmented in small isolated remnants, embedded in an inhospitable human-used matrix, and incur strong anthropogenic pressures (recreational activities, artificialization, pollution and eutrophication). These lead to particularly high constraints even for common forest herbs, whose genetic response may depend on life-history traits and population demographic status. This study investigated genetic variation and structure for 20 allozyme loci in 14 populations of Primula elatior, a self-incompatible long-lived perennial herb, occurring in forest fragments of Brussels urban zone (Belgium), in relation to population size and young plants recruitment rate. Urban populations of P. elatior were not genetically depauperate, but the small populations showed reduced allelic richness. Small populations showing high recruitment rates—and therefore potential rejuvenation—revealed lower genetic diversity (H _o and H _e) than those with low or no recruitment. No such pattern was observed for the large populations. There was a significant genetic differentiation among populations within forest fragments (F _SC = 0.052, P < 0.001), but not between fragments (F _CT = 0.002, P > 0.10). These findings suggest restricted gene flow among populations within fragments and local processes (genetic drift, inbreeding) affecting small populations, strengthened when there is recruitment. Urban forest populations of long-lived perennial herbs can be of conservation value. However, restoration of small populations by increasing population size through regeneration by seedling recruitment may lead to negative genetic consequences. Additional management, aiming to restore gene flow among populations, may need to be applied to compensate the loss of genetic diversity and to reduce inbreeding.