Conservation genetic evaluation of Juniperus communis sensu lato in Slovakia

This study explores the population structure, hybridization, and adaptation of Juniperus communis sensu lato in the context of its current habitat fragmentation, using inter-primer binding site markers and needle morphometry. Three native juniper taxa in Slovakia were analyzed: J. communis ssp. communis, J. communis ssp. nana, and their putative hybrid, J. communis nothovar. intermedia. The results reveal a moderate overall structure (ΦPT = 0.115, p = 0.001), indicating high gene flow within ssp. communis and low gene flow between ssp. communis and ssp. nana. However, after correcting for non-neutral loci, the inter-subspecies differentiation dropped significantly, suggesting adaptive divergence despite substantial gene flow. This conclusion was further supported using admixture regression of needle morphometry and ΦPT-QST comparison. We show that adaptive genetic differentiation may play a more significant role than phenotypic plasticity in these traits, a key consideration in preventing outbreeding depression in conservation management. Importantly, we also provide evidence for intermediate admixture and distinct selection pressures within two populations of nothovar. intermedia (Stolica, Kralova Studna), which may qualify their recognition as evolutionarily significant units (ESUs).

Ionomic Parameters of Populations of Common Juniper (Juniperus communis L.) Depending on the Habitat Type

For the study of the ionomic parameters of Juniperus communis needles, fourteen sites covering most of the territory of Lithuania and belonging to distinct habitats (coastal brown dunes covered with natural Scots pine forests (G), Juniperus communis scrubs (F), transition mires and quaking bogs (D), subcontinental moss Scots pine forests (G), and xero-thermophile fringes) were selected. Concentrations of macro-, micro-, and non-essential elements were analyzed in current-year needles, sampled in September. According to the concentrations of elements in J. communis needles, the differences between the most contrasting populations were as follows: up to 2-fold for Mg, N, K, Ca, and Zn; 2- to 7-fold for P, Na, Fe, Cu, Al, Cr, Ni, and Pb; and 26- to 31-fold for Mn and Cd. The concentrations of Cd, Cr, and Ni in needles of J. communis did not reach levels harmful for conifers. When compared to all other habitats (B, F, G, and E), the populations from transition mires and quaking bogs (D) had significantly lower concentrations of main nutritional elements N (12176 µg/g d. m.), P (1054 µg/g d. m.), and K (2916 µg/g d. m.). In Juniperus communis scrubs (F), a habitat protected by EUNIS, the concentration of K in the needles was highest, while Zn and Cu concentrations were the lowest. Principal component (PC) analyses using concentrations of 15 elements as variables for the discrimination of populations or habitats allowed authors to distinguish F and B habitats from the E habitat (PC1) and F and D habitats from the G habitat (PC2). Discriminating between populations, the most important variables were concentrations of P, N, Mg, Ca, Cu, and K. Discriminating between habitats, the important variables were concentrations of N and P.

Molecular and Phytochemical Variability of Endemic Juniperus sabina var. balkanensis from Its Natural Range

Juniperus sabina L. var. balkanensis R.P. Adams & Tashev is a recently described endemic variety from the Balkan Peninsula. Its strong sprouting ability and fast vegetative propagation, on one hand, and fragmented distribution, on the other, can lead to lower genetic diversity in local populations and to the differentiation of populations. As there has been no detailed investigation of this variety, we studied Balkan natural populations using phytochemical and molecular markers. Leaf essential oils (EOs) were chosen based on their proven usability in the population studies of Juniperus taxa, while ISSRs (Inter Simple Sequence Repeats) have been used due to their high resolution. In addition, since this variety is best described using molecular markers, the chloroplast trnS-trnG region was amplified from individuals from different populations having different chemotypes. Based on the essential oil profile, three chemotypes could be identified with a difference in their distribution. The analysis of molecular variance showed moderate differentiation of populations and regions, attesting to the start of the separation of three regions in the Balkans: west, east and south. The bioclimatic and environmental parameters and sex of the individual did not influence the EO profile, although some of the compounds present in low-to-medium concentrations showed strong correlation with several bioclimatic parameters.

Genetic Evaluation of Juniperus sabina L. (Cupressaceae) in Arid and Semi-Arid Regions of China Based on SSR Markers

Juniperus sabina L., a shrub distributed in patches in arid and semi-arid areas of the northern hemisphere, plays an important role in preventing land desertification and maintaining ecosystems. However, few studies have reported genetic diversity and genetic structure of widely distributed populations of J. sabina in northwest China. Here, we evaluated the genetic diversity and genetic structure and predicted the isolation barriers among 11 populations based on 20 simple sequence repeats (SSRs). A total of 134 alleles were generated and the average number of alleles per locus was 6.70. The Shannon diversity index ranged from 0.659 to 0.951, with an average of 0.825. Population structure analysis revealed that the populations were assigned into two genetic groups. The analysis of molecular variance (AMOVA) indicated that 88% of genetic variation existed within populations. Moderate population differentiation was occurred with FST value of 0.090. Finally, we concluded that geographic isolation is the main factor affecting the genetic structure of J. sabina populations. The results of this study provide a foundation for the strategies for J. sabina genetic conservation and management.

Using genetic evaluation to guide conservation of remnant Juniperus communis (Cupressaceae) populations

Many critically endangered plant species exist in small, genetically depauperate or inbred populations, making assisted gene flow interventions necessary for long-term population viability. However, before such interventions are implemented, conservation practitioners must consider the genetic and demographic status of extant populations, which are strongly affected by species' life-history traits. In northwestern Europe, Juniperus communis, a dioecious, wind-pollinated and bird-dispersed gymnosperm, has been declining for the past century and largely exists in small, isolated and senescent populations. To provide useful recommendations for a recovery plan involving translocation of plants, we investigated genetic diversity and structure of populations in Belgium using four microsatellite and five plastid single-nucleotide polymorphism (SNP) markers. We detected no clonality in the populations, suggesting predominantly sexual reproduction. Populations exhibited high genetic diversity (H_e  = 0.367-0.563) and low to moderate genetic differentiation (F_ST  ≤ 0.133), with no clear geographic structure. Highly positive inbreeding coefficients (F_IS  = 0.221-0.507) were explained by null alleles, population substructuring and biparental inbreeding. No isolation by distance was observed among distant populations, but isolation at close geographic proximity was found. Patterns were consistent with high historical gene flow through pollen and seed dispersal at both short and long distances. We also tested four pre-germination treatments among populations to improve germination rates; however, germination rates remained low and only cold-stratification treatments induced germination in some populations. To bolster population regeneration, introductions of cuttings from several source populations are recommended, in combination with in situ management practices that improve seedling survival and with ex situ propagation.