Abies guatemalensis Rehder, an endangered conifer endemic to Central American highlands, is ecologically vital in upper montane forests. It faces threats from habitat fragmentation, unsustainable logging, and illegal Christmas tree harvesting. While previous genetic studies on mature trees from eighteen populations showed high within-population diversity and limited among-population differentiation, the genetic impact of recent anthropogenic pressures on younger generations has yet to be discovered. Understanding these effects is crucial for developing effective conservation strategies for this vulnerable species. We sampled 170 young trees (< 15 years old) from seven populations across Guatemala. Seven microsatellite markers were used to analyse genetic diversity, population structure, and recent demographic history. Moderate levels of genetic diversity were observed within populations (mean Shannon diversity index = 4.97, mean Simpson's index = 0.51, mean allelic richness = 11.59, mean observed heterozygosity = 0.59). Although genetic structure broadly aligned with mountain corridors, substantial admixture patterns suggest historical connectivity across all populations. Most populations showed evidence of recent bottlenecks (p < 0.05) and inbreeding. The results suggest a potential decline in genetic diversity and increased population structuring (ΦST = 0.274, p < 0.01) over the past decades compared to the previous study on old trees. The observed genetic patterns indicate ongoing impacts of habitat fragmentation and anthropogenic pressures on A. guatemalensis. Conservation efforts should prioritise expanding effective population sizes and facilitating gene flow, particularly for isolated populations. While restoration efforts may be logistically easier within mountain ranges, genetic evidence suggests that increasing overall population connectivity could benefit this species. Management strategies should implement systematic seed collection protocols to maintain genetic diversity in future populations. These findings highlight the urgent need for conservation measures to preserve remaining genetic diversity and promote connectivity among A. guatemalensis populations.

• Klíčová slova
• Conservation, Gene flow, Genetic bottleneck, Guatemalan fir, Inbreeding, Overexploitation,
• MeSH
• ekosystém * MeSH
• genetická variace * MeSH
• jedle * genetika   MeSH
• mikrosatelitní repetice * genetika   MeSH
• ohrožené druhy * MeSH
• populační genetika MeSH
• zachování přírodních zdrojů MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Guatemala MeSH

Sheep are one of the most important livestock species in Croatia, found mainly in the Mediterranean coastal and mountainous regions along the East Adriatic coast, well adapted to the environment and mostly kept extensively. Our main objective was therefore to map the positive selection of the X-chromosome (18,983 SNPs that passed quality control), since nothing is known about the adaptation genes on this chromosome for any of the breeds from the Balkan cluster. Analyses were performed on a sample of eight native Croatian breeds (101 females and 100 males) representing the East Adriatic metapopulation and on 10 mouflons (five females and males), all sampled in Croatia. Three classical within-population approaches (extreme Runs of Homozygosity islands, integrated Haplotype Score, and number of Segregating Sites by Length) were applied along with our new approach called Haplotype Richness Drop (HRiD), which uses only the information contained in male haplotypes. We have also shown that phylogenetic analyses, such as the Median-joining network, can provide additional information when performed with the selection signals identified by HRiD. Our new approach identifies positive selection signals by searching for genomic regions that exhibit a sudden decline in haplotype richness. In total, we identified 14 positive selection signals, 11 using the classical approach and three using the HRiD approach, all together containing 34 annotated genes. The most reliable selection signal was mapped by all four approaches in the same region, overlapping between 13.17 and 13.60 Mb, and assigned to the CA5B, ZRSR2, AP1S2, and GRPR genes. High repeatability (86%) of results was observed, as 12 identified selection signals were also confirmed in other studies with sheep. HRiD offers an interesting possibility to be used complementary to other approaches or when only males are genotyped, which is often the case in genomic breeding value estimations. These results highlight the importance of the X-chromosome in the adaptive architecture of domestic ruminants, while our novel HRiD approach opens new possibilities for research.

• Klíčová slova
• X-chromosome, haplotype richness drop, integrated haplotype score, number of segregating sites by length, runs of homozygosity, selection signals, sheep,
• Publikační typ
• časopisecké články MeSH

BACKGROUND AND AIMS: Rubus subgenus Rubus is a group of mostly apomictic and polyploid species with a complicated taxonomy and history of ongoing hybridization. The only polyploid series with prevailing sexuality is the series Glandulosi , although the apomictic series Discolores and Radula also retain a high degree of sexuality, which is influenced by environmental conditions and/or pollen donors. The aim of this study is to detect sources of genetic variability, determine the origin of apomictic taxa and validate microsatellite markers by cloning and sequencing. METHODS: A total of 206 individuals from two central European regions were genotyped for 11 nuclear microsatellite loci and the chloroplast trn L- trn F region. Microsatellite alleles were further sequenced in order to determine the exact repeat number and to detect size homoplasy due to insertions/deletions in flanking regions. KEY RESULTS: The results confirm that apomictic microspecies of ser. Radula are derived from crosses between sexual series Glandulosi and apomictic series Discolores , whereby the apomict acts as pollen donor. Each apomictic microspecies is derived from a single distinct genotype differing from the parental taxa, suggesting stabilized clonal reproduction. Intraspecific variation within apomicts is considerably low compared with sexual series Glandulosi , and reflects somatic mutation accumulation. While facultative apomicts produce clonal offspring, sexual species are the conduits of origin for new genetically different apomictic lineages. CONCLUSIONS: One of the main driving forces of evolution and speciation in the highly apomictic subgenus Rubus in central Europe is sexuality in the series Glandulosi . Palaeovegetation data suggest that initial hybridizations took place over different time periods in the two studied regions, and that the successful origin and spread of apomictic microspecies of the series Radula took place over several millennia. Additionally, the cloning and sequencing show that standard evaluations of microsatellite repeat numbers underestimate genetic variability considering homoplasy in allele size.

• Klíčová slova
• Apomixis, Rubus subgenus Rubus, hybridization, microevolution, microsatellites, polyploidy,
• MeSH
• apomixie * MeSH
• DNA chloroplastová genetika   MeSH
• hybridizace genetická * MeSH
• mikrosatelitní repetice * MeSH
• mutace INDEL MeSH
• polyploidie MeSH
• Rubus klasifikace   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• DNA chloroplastová MeSH

Microsatellites, or simple sequence repeats (SSRs) are widespread class of repetitive DNA sequences, used in population genetics, genetic diversity and mapping studies. In spite of the SSR utility, the genetic and evolutionary mechanisms are not fully understood. We have investigated three microsatellite loci with different position in the pea (Pisum sativum L.) genome, the A9 locus residing in LTR region of abundant retrotransposon, AD270 as intergenic and AF016458 located in 5'untranslated region of expressed gene. Comparative analysis of a 35 pair samples from seven pea varieties propagated by single-seed descent for ten generations, revealed single 4 bp mutation in 10th generation sample at AD270 locus corresponding to stepwise increase in one additional ATCT repeat unit. The estimated mutation rate was 4.76 × 10(-3) per locus per generation, with a 95% confidence interval of 1.2 × 10(-4) to 2.7 × 10(-2). The comparison of cv. Bohatýr accessions retrieved from different collections, showed intra-, inter-accession variation and differences in flanking and repeat sequences. Fragment size and sequence alternations were also found in long term in vitro organogenic culture, established at 1983, indicative of somatic mutation process. The evidence of homoplasy was detected across of unrelated pea genotypes, which adversaly affects the reliability of diversity estimates not only for diverse germplasm but also highly bred material. The findings of this study have important implications for Pisum phylogeny studies, variety identification and registration process in pea breeding where mutation rate influences the genetic diversity and the effective population size estimates.

• MeSH
• 5' nepřekládaná oblast MeSH
• chov MeSH
• DNA rostlinná genetika   izolace a purifikace   MeSH
• genetická variace MeSH
• genom rostlinný MeSH
• genotyp MeSH
• hrách setý genetika   MeSH
• intergenová DNA MeSH
• koncové repetice MeSH
• mikrosatelitní repetice * MeSH
• mutace * MeSH
• nestabilita genomu MeSH
• retroelementy MeSH
• rodokmen * MeSH
• sekvenční analýza DNA MeSH
• semena rostlinná genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 5' nepřekládaná oblast MeSH
• DNA rostlinná MeSH
• intergenová DNA MeSH
• retroelementy MeSH

BACKGROUND: Quest for understanding the nature of mechanisms governing the life span of clonal organisms lasts for several decades. Phylogenetic evidence for recent origins of most clones is usually interpreted as proof that clones suffer from gradual age-dependent fitness decay (e.g. Muller's ratchet). However, we have shown that a neutral drift can also qualitatively explain the observed distribution of clonal ages. This finding was followed by several attempts to distinguish the effects of neutral and non-neutral processes. Most recently, Neiman et al. 2009 (Ann N Y Acad Sci.:1168:185-200.) reviewed the distribution of asexual lineage ages estimated from a diverse array of taxa and concluded that neutral processes alone may not explain the observed data. Moreover, the authors inferred that similar types of mechanisms determine maximum asexual lineage ages in all asexual taxa. In this paper we review recent methods for distinguishing the effects of neutral and non-neutral processes and point at methodological problems related with them. RESULTS AND DISCUSSION: We found that contemporary analyses based on phylogenetic data are inadequate to provide any clear-cut answer about the nature and generality of processes affecting evolution of clones. As an alternative approach, we demonstrate that sequence variability in asexual populations is suitable to detect age-dependent selection against clonal lineages. We found that asexual taxa with relatively old clonal lineages are characterised by progressively stronger deviations from neutrality. CONCLUSIONS: Our results demonstrate that some type of age-dependent selection against clones is generally operational in asexual animals, which cover a wide taxonomic range spanning from flatworms to vertebrates. However, we also found a notable difference between the data distribution predicted by available models of sequence evolution and those observed in empirical data. These findings point at the possibility that processes affecting clonal evolution differ from those described in recent studies, suggesting that theoretical models of asexual populations must evolve to address this problem in detail. REVIEWERS: This article was reviewed by Isa Schön (nominated by John Logsdon), Arcady Mushegian and Timothy G. Barraclough (nominated by Laurence Hurst).

• MeSH
• biologická evoluce * MeSH
• genetická variace genetika   MeSH
• nepohlavní rozmnožování MeSH
• populační genetika metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

One hundred and sixty-four accessions representing Czech and Slovak pea (Pisum sativum L.) varieties bred over the last 50 years were evaluated for genetic diversity using morphological, simple sequence repeat (SSR) and retrotransposon-based insertion polymorphism (RBIP) markers. Polymorphic information content (PIC) values of 10 SSR loci and 31 RBIP markers were on average high at 0.89 and 0.73, respectively. The silhouette method after the Ward clustering produced the most probable cluster estimate, identifying nine clusters from molecular data and five to seven clusters from morphological characters. Principal component analysis of nine qualitative and eight quantitative morphological parameters explain over 90 and 93% of total variability, respectively, in the first three axes. Multidimensional scaling of molecular data revealed a continuous structure for the set. To enable integration and evaluation of all data types, a Bayesian method for clustering was applied. Three clusters identified using morphology data, with clear separation of fodder, dry seed and afila types, were resolved by DNA data into 17, 12 and five sub-clusters, respectively. A core collection of 34 samples was derived from the complete collection by BAPS Bayesian analysis. Values for average gene diversity and allelic richness for molecular marker loci and diversity indexes of phenotypic data were found to be similar between the two collections, showing that this is a useful approach for representative core selection.

• MeSH
• alely MeSH
• analýza hlavních komponent MeSH
• Bayesova věta MeSH
• frekvence genu MeSH
• genetická variace * MeSH
• genetické markery genetika   MeSH
• hrách setý genetika   MeSH
• mikrosatelitní repetice genetika   MeSH
• minisatelitní repetice genetika   MeSH
• populační dynamika MeSH
• retroelementy genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• genetické markery MeSH
• retroelementy MeSH