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Auteur Jon Ågren |
Documents disponibles écrits par cet auteur (2)
Affiner la rechercheGender variation and sexual differences in reproductive characters and seed production in gynodioecious Geranium maculatum / Jon Ågren in American Journal of Botany, 78 (4) (1991)
Titre : Gender variation and sexual differences in reproductive characters and seed production in gynodioecious Geranium maculatum Type de document : Imprimé Auteurs : Jon Ågren ; Mary F. Willson (1938-) Année de publication : 1991 Article en page(s) : 470-480 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Biologie de la reproduction
[CBNPMP-Thématique] Stratégie de production de semences (fécondité)Mots-clés : Geranium Résumé : Variation in sex expression, flowering pattern, and seed production was studied in the self-compatible perennial herb Geranium maculatum in Illinois and Indiana. In a survey of eight populations, female (male-sterile) plants were found in seven (frequencies ranging from 0.5% to 24.3% [median 4.2%]), and intermediate plants (with partly reduced male function) were found in all populations. Gender variation and sexual differences in reproductive characters were studied in detail in two populations. One population consisted of 5% female, 27% intermediate, and 68% hermaphrodite plants; the other consisted of 1% female, 20% intermediate, and 79% hermaphrodite plants. Females produced smaller flowers and began flowering earlier than hermaphrodites. Intermediates produced flowers of an intermediate size and began flowering as early as females. Females and hermaphrodites did not differ in flower number, vegetative size, flowering frequency, survival, or seed size. However, females produced 1.6 times more seeds than hermaphrodites. Intermediates produced 1.3–1.6 times more seeds than hermaphrodites. Some between-year variation in sex expression was observed. Hand-pollination with outcross pollen produced two to four times as many seeds as hand-pollination with self-pollen. A lower outcrossing rate in hermaphrodites than in females may at least partly explain the lower seed set in hermaphrodites. The higher seed production of females, and possibly the high fecundity of the intermediates, should contribute to the maintenance of this sexual polymorphism. Identifiant : DOI : 10.1002/j.1537-2197.1991.tb15213.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137573
in American Journal of Botany > 78 (4) (1991) . - 470-480Ågren, Jon, Willson, Mary F. (1938-) 1991 Gender variation and sexual differences in reproductive characters and seed production in gynodioecious Geranium maculatum. American Journal of Botany, 78(4): 470-480.Documents numériques
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article (1991)URL
Titre : Landscape structure, clonal propagation and genetic diversity in Scandinavian populations of Arabidopsis lyrata (Brassicaceae) Type de document : Numérique Auteurs : Myriam Gaudeul (1976-) ; Hans K. Stenøien ; Jon Ågren Année de publication : 2007 Article en page(s) : 1146-1155 Langues : Anglais (eng) Résumé : Colonization history, landscape structure, and environmental conditions may influence patterns of neutral genetic variation because of their effects on gene flow and reproductive mode. We compared variation at microsatellite loci within and among 26 Arabidopsis lyrata populations in two disjunct areas of its distribution in northern Europe (Norway and Sweden). The two areas probably share a common colonization history but differ in size (Norwegian range markedly larger than Swedish range), landscape structure (mountains vs. coast), and habitat conditions likely to affect patterns of gene flow and opportunities for sexual reproduction. Within-population genetic diversity was not related to latitude but was higher in Sweden than in Norway. Population differentiation was stronger among Norwegian than among Swedish populations (F(ST) = 0.23 vs. F(ST) = 0.18). The frequency of clonal propagation (proportion of identical multilocus genotypes) increased with decreasing population size, was higher in Norwegian than in Swedish populations, but was not related to altitude or substrate. Differences in genetic structure are discussed in relation to population characteristics and range size in the two areas. The results demonstrate that the possibility of clonal propagation should be considered when developing strategies for sampling and analyzing data in ecological and genetic studies of this emerging model species. Identifiant : DOI : 10.3732/ajb.94.7.1146 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=140697
in American Journal of Botany > 94 (2007) . - 1146-1155Gaudeul, Myriam (1976-), Stenøien, Hans K., Ågren, Jon 2007 Landscape structure, clonal propagation and genetic diversity in Scandinavian populations of Arabidopsis lyrata (Brassicaceae). American Journal of Botany, 94: 1146-1155.Documents numériques
Article (2007)URL
