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Auteur ]. Gerard B. Oostermeijer |
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Offspring fitness in relation to population size and genetic variation in the rare perennial plant species Gentiana pneumonanthe (Gentianaceae) / ]. Gerard B. Oostermeijer in Oecologia, vol. 97 (Année 1994)
[article]
Titre : Offspring fitness in relation to population size and genetic variation in the rare perennial plant species Gentiana pneumonanthe (Gentianaceae) Auteurs : ]. Gerard B. Oostermeijer, Auteur ; M.W. van Eijck, Auteur ; J. C. M. den Nijs, Auteur Année de publication : 1994 Article en page(s) : pp. 289-293 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Gentiana pneumonanthe
[Thèmes] Biologie de la conservation
[Thèmes] Conservation
[Thèmes] Germination des graines
[Thèmes] Plante à forte valeur patrimonialeMots-clés : variation génétique Résumé : "Seeds were sampled from 19 populations of the rare Gentiana pneumonanthe, ranging in size from 5 to more than 50,000 flowering plants. An analysis was made of variation in a number of life-history characters in relation to population size and offspring heterozygosity (based on seven polymorphic isozyme loci). Life-his-tory characters included seed weight, germination rate, proportion of seeds germinating, seedling mortality, seedling weight, adult weight, flower production per plant and proportion of plants flowering per family. Principal component analysis (PCA) reduced the dataset to three main fitness components. The first component was highly correlated with adult weight and flowering performance, the second with germination performance and the third component with seed and seedling weight and seedling mortality. The latter two components were considered as being maternally influenced, since these comprised life-history traits that were significantly correlated with seed weight. Multiple regression analysis showed that variation in the first fitness component was mainly associated with heterozygosity and not with population size, while the third fitness component was only correlated with population size and not with heterozygosity. The latter relationship appeared to be non-linear, which suggests a stronger loss of fitness in the smallest populations. The second (germination) component was neither correlated with population size nor with genetic variation. There was only a weak association between population size, heterozygosity and the population coefficients of variation for each life history character. Most correlation coefficients were negative, however, which suggests that there is more variation among progeny from smaller populations. We conclude that progeny from small populations of Gentiana pneumonanthe show reduced fitness and may be phenotypically more variable. One of the possible causes of the loss of fitness is a combination of unfavourable environmental circumstances for maternal plants in small populations and increased inbreeding. The higher phenotypic variation in small populations may also be a result of inbreeding, which can lead to deviation of individuals from the average phenotype through a loss of developmental stability." (source : auteurs) Type de publication : périodique Référence biblio : Oostermeijer J.-G.-B., van Eijck M.-W., den Nijs J.-C.-M., 1994 - Offspring fitness in relation to population size and genetic variation in the rare perennial plant species Gentiana pneumonanthe (Gentianaceae). Oecologia, 97 : 289-293. ID PMB : 71994 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71994
in Oecologia > vol. 97 (Année 1994) . - pp. 289-293[article]Exemplaires(0)
Disponibilité aucun exemplaire Population biology and management of the marsh gentian (Gentiana pneumonanthe L.), a rare species in The Netherlands / ]. Gerard B. Oostermeijer in Botanical Journal of the Linnean Society, vol. 108, n°2 (Année 1992)
[article]
Titre : Population biology and management of the marsh gentian (Gentiana pneumonanthe L.), a rare species in The Netherlands Auteurs : ]. Gerard B. Oostermeijer, Auteur ; J. C. M. den Nijs, Auteur ; Leon E. L. Raijmann, Auteur Année de publication : 1992 Article en page(s) : pp. 117-130 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Gentiana pneumonanthe
[Thèmes] Conservation
[Thèmes] Pays basque
[Thèmes] Plante à forte valeur patrimonialeMots-clés : gestion suivi biologie des populations Résumé : "A broad study into the population biology of the marsh gentian has revealed so far that in The Netherlands there are two types of populations, characterized by a different demographic behaviour, viz. 'dynamic' populations, with high seedling turnover and low percentage of adult flowering plants, and 'static' or 'senile' populations, consisting mostly of flowering individuals and with hardly any seedlings. Also, populations encounter problems due to increasing isolation and decreasing numbers of individuals. Important parameters, such as seedling recruitment, seedling growth potential, seed production, rates of outcrossing and gene flow and the degree of genetic variation, all appear to be reduced in small populations. An evaluation of the effects of different management strategies, based on population ecological studies, is discussed as well." (source : auteurs) Type de publication : périodique Référence biblio : Oostermeijer ].-G., den Nijs J.-C.-M., Raijmann L.-L., 1992 - Population biology and management of the marsh gentian (Gentiana pneumonanthe L.), a rare species in The Netherlands. Botanical Journal of the Linnean Society, 108 (2) : 117-130. ID PMB : 71996 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71996
in Botanical Journal of the Linnean Society > vol. 108, n°2 (Année 1992) . - pp. 117-130[article]Exemplaires(0)
Disponibilité aucun exemplaire Population structure of the rare, long-lived perennial Gentiana pneumonanthe in relation to vegetation and management in the Netherlands / ]. Gerard B. Oostermeijer in Journal of Applied Ecology, vol. 31 (Année 1994)
[article]
Titre : Population structure of the rare, long-lived perennial Gentiana pneumonanthe in relation to vegetation and management in the Netherlands Auteurs : ]. Gerard B. Oostermeijer, Auteur ; R. van 't Veer, Auteur ; J. C. M. den Nijs, Auteur Année de publication : 1994 Article en page(s) : pp. 428-438 Langues : Anglais (eng) Catégories : [ZG] Pays-Bas
[Espèces (in biblio)] Gentiana pneumonanthe
[Thèmes] Conservation
[Thèmes] Plante à forte valeur patrimonialeMots-clés : suivi Résumé : "1. After analysis of population age-state spectra of Gentiana pneumonanthe in a variety of vegetation types, three different population types could be distinguished: (a) `invasive' or `dynamic' populations, characterized by high densities of seedlings and juveniles relative to the adult age states, (b) `normal' or `stable' populations with adult age states prevailing, but with low densities of seedlings and juveniles, and (c) `regressive' or `senile' populations, consisting only of adult flowering and adult vegetative individuals.
2. The structure of the surrounding vegetation appears to be very important in determining the population structure of the marsh gentian. In particular the percentage of bare soil surface and the cover of the litter layer explain most of the variation in the density and proportion of different age states in the populations. The area of bare soil surface in the vegetation increases the percentage of seedlings and juveniles in the population and, consequently, decreases the proportion of generative adults, while the reverse is true for the cover of the litter layer.
3. In heathlands, a clear trend can be observed in the age state structure from `invasive' populations in young successional stages, via `normal' populations in relatively stable situations, to `regressive' populations in late successional stages or unmanaged areas dominated by grasses or shrubs. In hay meadows, `normal' populations are usually observed, except where mowing has been stopped or where a combination of early mowing and acidification exists. This leads to closure of the community by grasses or bryophytes, respectively, and therefore to a `regressive' population structure.
4. Individuals in heathland and grassland populations seem to have a different lifestrategy because of the differences in vegetation dynamics between these two habitat types. Ecotypic differentiation in life-history characteristics may therefore be expected.
5. It is argued that, as a basis for conservation and management, monitoring the age state structure of populations of rare perennial plant species is far more effective than counting only the flowering individuals, as is mostly done." (source : auteurs)Type de publication : périodique Référence biblio : Oostermeijer J.-G.-B., van 't Veer R., den Nijs J.-C.-M., 1994 - Population structure of the rare, long-lived perennial Gentiana pneumonanthe in relation to vegetation and management in the Netherlands. Journal of Applied Ecology, 31 : 428-438. ID PMB : 71995 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71995
in Journal of Applied Ecology > vol. 31 (Année 1994) . - pp. 428-438[article]Exemplaires(0)
Disponibilité aucun exemplaire Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands / S.H. Luijten in Folia Geobotanica, vol. 34, n°4 (Année 1999)
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Titre : Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands Auteurs : S.H. Luijten, Auteur ; ]. Gerard B. Oostermeijer, Auteur ; A.C. Ellis-Adam, Auteur ; J.H.C.M. (den) Nijs, Auteur Année de publication : 1999 Article en page(s) : pp. 483-496 Langues : Anglais (eng) Catégories : [ZG] Pays-Bas
[Espèces (in biblio)] Gentiana germanica
[Thèmes] Plante à forte valeur patrimoniale
[Thèmes] Pollinisation, pollen, nectarRésumé : "Gentianella germanica (Willd.) Börner, a rare plant species, occurs at the margin of its distribution area in the Netherlands. It is found only in isolated patches of chalk grassland surrounded by intensively-used agricultural land. In 1997 and 1998, we investigated the spatial and temporal separation of anthers and stigma in relation to autofertility. We performed our experiments in one large and two small populations to investigate the possible selection against herkogamy and for increased autofertility in marginal populations with pollination limitation. Dichogamy appeared to be very weak and varied within individuals. Homogamous and protandrous flowers were most frequent. Dichogamy is apparently no effective barrier against self-fertilization in this species. Herkogamy varied significantly between individuals and between populations, and plant and flower size were not correlated with anther-stigma separation. Both observations suggest a genetic basis for herkogamy. Autofertility was generally high in all three populations. Only in one small population was a correlation between autofertility and herkogamy found. In this population, most plants had the stigma positioned above the anthers (mean herkogamy +0.8 mm), while in the other two populations the stigma was positioned mainly in between or below the anthers (mean herkogamy −0.55 mm). In comparison with earlier data from 1991 and 1992, plants in the large population were less herkogamous and more self-fertile in 1998. Since 1993 this population was mown each year one month earlier than usual, leading to dramatic reductions (bottlenecks) in population size. In addition, the early mowing time may have caused a further reduction of the already scarce visitation by pollinating insects. We hypothesize that both adverse conditions may have caused a selection of plants with smaller anther-stigma separation and higher autofertility and thus showing that human influence can have profound effects on the reproductive success and evolution of rare plant species, even if it occurs in the context of nature conservation." (source : auteurs) Type de publication : périodique Référence biblio : Luijten S.-H., Oostermeijer ].-G., Ellis-Adam A.-C., Nijs J.-H.-C.-M. (den), 1999 - Variable herkogamy and autofertility in marginal populations of Gentianella germanica in the Netherlands. Folia Geobotanica, 34 (4) : 483-496. ID PMB : 17464 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=17464
in Folia Geobotanica > vol. 34, n°4 (Année 1999) . - pp. 483-496[article]Exemplaires(1)
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