Most cited article - PubMed ID 21642109
Genetic structure of experimental populations and reproductive fitness in a heterocarpic plant Atriplex tatarica (Chenopodiaceae)
Rumex alpinus L. (R. alpinus) is a non-native invasive plant in Czech mountain regions, altering ecosystem structure and function in protected areas. Rumex obtusifolius L. (R. obtusifolius) is a native species and a problematic weed in Czech meadows, while Rumex longifolius DC. (R. longifolius) is characteristic of Fennoscandia and widespread in northern and central Europe. This study explores temperature-driven germination patterns in R. alpinus, R. obtusifolius, and R. longifolius and also focuses on potential differences across populations of R. alpinus. The hypothesis suggests that R. alpinus is not established in lowland areas due to temperature limitations during germination. A second experiment evaluates the influence of native and non-native localities on R. alpinus seed germination. The primary experiment was conducted at 6°C, 12°C, 18°C, 24°C, 29°C, and 35°C in a climate chamber, while the second experiment was performed at 24°C for 14 days. Contrary to expectations, R. alpinus exhibited the highest germination rate across all temperatures. In the second experiment, germination rates varied significantly, with a positive correlation between germination success and transition from Alpine to Czech localities. The highest and fastest germination was observed in seeds from the Krkonoše Mountains, where R. alpinus is an invasive plant species.
- Keywords
- alpine dock, broad‐leaved dock, invasive plant, long‐leaved dock, mountain plants, weeds,
- Publication type
- Journal Article MeSH
Many ephemeral mudflat species, which rely on a soil seed bank to build up the next generation, are endangered in their natural habitat due to the widespread regulation of rivers. The aim of the present study was to elucidate the role of the soil seed bank and dispersal for the maintenance of genetic diversity in populations of near-natural river habitats and anthropogenic habitats created by traditional fish farming practices using Cyperus fuscus as a model. Using microsatellite markers, we found no difference in genetic diversity levels between soil seed bank and above-ground population and only moderate differentiation between the two fractions. One possible interpretation is the difference in short-term selection during germination under specific conditions (glasshouse versus field) resulting in an ecological filtering of genotypes out of the reservoir in the soil. River populations harbored significantly more genetic diversity than populations from the anthropogenic pond types. We suggest that altered levels and patterns of dispersal together with stronger selection pressures and historical bottlenecks in anthropogenic habitats are responsible for the observed reduction in genetic diversity. Dispersal is also supposed to largely prohibit genetic structure across Europe, although there is a gradient in private allelic richness from southern Europe (high values) to northern, especially north-western, Europe (low values), which probably relates to postglacial expansion out of southern and/or eastern refugia.
- Keywords
- Cyperus fuscus, Isoëto‐Nanojuncetea, long‐distance dispersal, microsatellites, ornithochory, selfing,
- Publication type
- Journal Article MeSH
PREMISE OF THE STUDY: Microsatellite primers were developed to characterize the genetic diversity and structure of the annual herb Atriplex tatarica (Amaranthaceae) and to facilitate ecological and evolutionary studies of A. tatarica and its relatives. METHODS AND RESULTS: Sixteen novel microsatellite primers were developed for A. tatarica based on high-throughput sequencing of enriched libraries. All markers were polymorphic, with the number of alleles per locus ranging from three to 25 and observed and expected heterozygosity ranging from 0.08 to 0.74 and 0.10 to 0.87, respectively. In addition, some of these loci were successfully amplified and showed polymorphisms in four Atriplex and seven Chenopodium species. CONCLUSIONS: The microsatellite markers published here will be useful in assessing genetic diversity, structure, and gene flow within and across populations of A. tatarica, as well as in other species of Atriplex and the related genus Chenopodium.
- Keywords
- Amaranthaceae, Atriplex, Chenopodium, cross-amplification, microsatellites,
- Publication type
- Journal Article MeSH
We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we analysed the extent to which allele and genotype frequencies vary in consecutive life history stages including the summer seed bank, which has been overlooked up to now. We compared the winter seed bank (i.e., seeds collected before the spring germination peak), seedlings, rosettes, the summer seed bank (i.e., seeds collected after the spring germination peak) and fruiting plants. We found that: (1) All three species partitioned most of their genetic diversity within life history stages and less among stages within populations and among populations. (2) All genetic diversity parameters, except for allele frequencies, were similar among all life history stages across all populations in different species. (3) There were differences in allele frequencies among life history stages at all localities in Amaranthus retroflexus and at three localities in both Carduus acanthoides and Pastinaca sativa. (4) Allele frequencies did not differ between the winter and summer seed bank in most Carduus acanthoides and Pastinaca sativa populations, but there was a marked difference in Amaranthus retroflexus. In conclusion, we have shown that the summer seed bank is not genetically depleted by spring germination and that a majority of genetic diversity remains in the soil through summer. We suggest that seed banks in the species investigated play an important role by maintaining genetic diversity sufficient for recovery rather than by accumulating new genetic diversity at each locality.
- MeSH
- Alleles MeSH
- Amaranthus physiology MeSH
- Carduus physiology MeSH
- Species Specificity MeSH
- Ecosystem MeSH
- Genetic Variation MeSH
- Models, Genetic MeSH
- Pastinaca physiology MeSH
- Soil analysis MeSH
- Seasons MeSH
- Plants genetics MeSH
- Seeds chemistry genetics MeSH
- Models, Statistical MeSH
- Geography MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Soil MeSH
BACKGROUND AND AIMS: The heterocarpic species Atriplex tatarica produces two types of seeds. In this study, how basic population genetic parameters correlate with seed germinability under various experimental conditions was tested. METHODS: Population genetic diversity was ascertained in eight populations of A. tatarica by assessing patterns of variation at nine allozyme loci. Germinability of both seed types from all sampled populations was determined by a common laboratory experiment under different salinity levels. Basic population genetic parameters, i.e. percentage of polymorphic loci, average number of alleles per locus and observed heterozygosity were correlated with observed population germination characteristics. KEY RESULTS: Atriplex tatarica possesses a remarkable heterocarpy, i.e. one type of seed is non-dormant and the other shows different dormancy levels in relation to experimental conditions. Significant negative correlations have been detected between germination of both seed types and the coefficient of inbreeding, and a significant negative correlation between germination of dormant seeds and other population genetic parameters, i.e. percentage of polymorphic loci and average number of alleles per polymorphic locus. Moreover, populations from the region characterized by a shorter growing season manifested higher germinability, i.e. had lower dormancy, than those from the lower-latitude one. CONCLUSIONS: In general, germination of non-dormant seeds is probably not under strong genetic control. Hence, they germinate as soon as conditions are favourable, thus ensuring survival in the short term, but populations risk local extinction if conditions become adverse (i.e. a high-risk strategy). In contrast, germination of the dormant type of seeds is under stronger genetic control and is significantly correlated with basic population genetic parameters. These seeds ensure long-term reproduction and survival in the field by protracted germination, albeit in low quantities (i.e. A. tatarica also adopts a low-risk strategy).
