Emilia Brzosko

Spatial genetic structure and clonal diversity of island populations of lady's slipper (Cypripedium calceolus) from the Biebrza National Park (northeast Poland).

Three populations of the rare and endangered plant species Cypripedium calceolus were included in a study of genetic diversity and spatial genetic structure in the Biebrza National Park, northeast Poland. Analysis of 11 allozyme loci indicate that the populations of this species contained high genetic variability (P = 45.5%, A= 1.73). On the other hand, the genetic differentiation (FST = 0.014, P < 0.05) among C. calceolus populations was very low when compared to other species with similar life history characteristics. The observed high rate of gene flow (Nm = 18) may suggest that the populations studied derived from each other in the recent past. Five polymorphic allozyme markers identified 109 multilocus genotypes in three populations and the majority of them (67%) were population‐specific. One of the populations studied, characterized by particularly extensive vegetative reproduction, showed the lowest clonal diversity (G/N = 0.15) and heterozygosity (HO = 0.111) values and the highest FIS(0.380), when compared to other two populations (G/N = 0.26–0.27, HO= 0.166–178, FIS = 0.024–0.055). This may indicate that clonal reproduction has an important influence on the genetic structure of C. calceolus populations. The longevity of genets, the out‐crossing breeding system and the presence of recruitment from seeds are factors maintaining genetic diversity in C. calceolus.

Selfing potential in Epipactis palustris , E. helleborine and E. atrorubens (Orchidaceae)

Factors enabling and limiting self-fertilization were examined in populations of Epipactispalustris, E. helleborine and E. atrorubens located in NE Poland. In these species we found self-compatibility within the same flower (even 100% of fruit set from induced autogamy) and the same inflorescence (reaching 90–100% of fruit set from induced geitonogamy). Facultative autogamy was found only in E. palustris (even 82.5% of fruit set in a bagged inflorescence), due to underdevelopment of the clinandrium and projection of pollinia over the rostellum. Allogamy was predominant in E. helleborine (maximum to 2.8% of fruits set spontaneously) and E. atrorubens (maximum to 3.4%), attributable to a well-developed rostellum and clinandrium and to the position of pollinia. Autonomous selfing takes place during flower wilting, when the viscidium becomes evanescent and the pollinia are fragile. Selfing is enabled mostly by pollinator behaviour, promoting both geitonogamy and autogamy, and influencing mixed-mating.

Patterns of Genetic Diversity in Platanthera bifolia (Orchidaceae) with Respect to Life History Traits and Recent Range Expansion

For evolutionary and ecological analyses, genetic diversity at different scales needs to be studied in terms of biological properties, habitat, population size and population history. We surveyed Platanthera bifolia populations from six regions in northeastern Poland to determine the impact of the mating system and population history on genetic diversity. Based on variation at allozyme markers, genetic variation was relatively moderate (P = 22.3%, A = 1.48, HO = 0.083, FIS = −0.015) and similar to other Platanthera species. These parameters varied between populations (P = 13.3%–26.6%, A = 1.26–1.66, HO = 0.055–0.111, FIS = −0.262–0.147). The genetic diversity patterns were shaped by different proportions of facilitated selfing and/or outcrossing, resulting in positive and negative FIS values, respectively. No relationship between inbreeding coefficient and population size, however, and no impact of apomixis on the level of genetic diversity of P. bifolia were found. The relatively low level of genetic differentiation among the investigated regions (FCT = 0.002, P > 0.05) and among populations (FST = 0.048, P < 0.001), and the lack of a significant relationship between genetic and geographical distance, are discussed in the context of possible scenaria of postglacial expansion.

Genetic Diversity of Cypripedium calceolus at the Edge and in the Centre of Its Range in Europe

The patterns of genetic diversity in 14 Cypripedium calceolus populations were investigated in two distant regions, located inside its continuous range (Biebrza valley, NE Poland) and close to the periphery of its range (Alps, SE France). The genetic variation at the species level was found to be relatively high (P% = 37.5%, H o = 0.145) as compared with that observed in other endangered or rare species. The mean genetic diversity for both European regions did not differ significantly, except for P% (42.5% for Biebrza valley, 34.1% for Alps, p < 0.001). The Biebrza valley yielded almost twice as many genotypes, but genotypic diversity (as measured by G/N and Ĝ/N) was higher in populations from the Alps. This could mean that asexual reproduction is more intense in populations in the Biebrza valley than in the Alps. The results from PCA, UPGMA and AMOVA analyses showed clear genetic differences in C. calceolus between the two European regions. The Mantel test showed positive and significant associations between genetic and geographic distances among populations situated in the Biebrza valley (r 2 = 0.37, p < 0.05), but not among the Alpine populations (r 2 = -0.25, p > 0.05). Our data showed that substantial loss of genetic diversity in C. calceolus most likely occurs rather at the population than at the species level.

Cytotype distribution and colonization history of the steppe plant Iris aphylla.

The polyploid origin and colonization history of Iris aphylla in central and southeastern Europe were investigated by means of karyological and AFLP analyses. The study indicated two chromosome races within I. aphylla based on chromosomal numbers 2n = 24 and 2n = 48. The overall chromosome counts and determined ploidy suggest tetraploidy as the most common ploidy level for this species in Europe. Only one diploid I. aphylla population was found, with a restricted distribution area in the Slovak Karst. The analyses showed that tetraploids arose independently at least three or more times in the past. The karyological results were in agreement with the AFLP data and strongly suggested that migration between the two Carpathian Mts. sites occurred recently via the Dukielska Pass. The low number of AFLP fragments unique to each population supports the hypothesis of recent range expansion and colonization of different environments in central Europe by I. aphylla. All populations were genetically depauperated and had 0–3 unique bands, indicating that not enough time elapsed for many unique fragments to form through mutation. We also observed relatively high and significant differentiation between the one diploid and all investigated tetraploid I. aphylla populations (&PHgr;ST = 0.470, p < 0.001). The high and significant values of genetic differentiation can be explained by several factors such as anthropopression and natural succession, which have fragmented the open calcareous habitats in central Europe.

Genetic structure of dioecious and trioecious Salix myrsinifolia populations at the border of geographic range

Gene flow in plant populations is heavily affected by species sexual systems. In order to study the effect of sexual systems on genetic structure, we examined plastid and nuclear DNA of 12 dioecious (males and females) and 18 trioecious (males, females and hermaphrodites) populations of Salix myrsinifolia—a boreal shrub with slow range expansion. Populations were located along latitudinal gradients across submarginal and marginal parts of the range. Individuals of each sex morph were all hexaploid. We identified 10 chloroplast DNA haplotypes and scored 205 polymorphic bands with amplified fragment length polymorphism. We found dioecious populations that differed from trioecious populations via the presence of four unique haplotypes and significant difference in Nei’s gene diversity index (0.119 vs. 0.116) and down-weighed marker value (1.17 vs. 1.02). The latter parameter, together with haplotype and nucleotide diversity, significantly decreased with latitude similar to the expansion front. Also, we found that 89% of hermaphrodite individuals belong to one distinct in tree parsimony network haplotype. This frequency significantly decreased with latitude towards the expansion front. We suspect that the presence of hermaphrodites in trioecious populations may represent a trade-off between the possibility of producing progeny by single hermaphrodites and genetic variability loss through autogamy. S. myrsinifolia benefits from trioecious sexual systems under colonization events. This phenomenon is no longer a gain closer to the core of the species range.