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Auteur Christopher George Eckert (1960-) |
Documents disponibles écrits par cet auteur (5)
Affiner la rechercheDoes self-pollination provide reproductive assurance in Aquilegia canadensis (Ranunculaceae)? / Christopher George Eckert in American Journal of Botany, 85 (7) (07/1998)
Titre : Does self-pollination provide reproductive assurance in Aquilegia canadensis (Ranunculaceae)? Type de document : Imprimé Auteurs : Christopher George Eckert (1960-) ; A. Schaefer Année de publication : 1998 Article en page(s) : 919-924 Langues : Anglais (eng) Mots-clés : Aquilegia sp. Aquilegia canadensis Résumé : The ability to produce seeds when pollinators or potential mates are scarce is thought to be one of the main advantagesof self-fertilization in flowering plants. However, whether autonomous selfing increases seed set in natural populations hasseldom been tested, and even fewer studies have evaluated the advantage of selfing across a gradient of pollen availability.This study examines the fertility consequences of autonomous selfing inAquilegia canadensis(Ranunculaceae), a short-lived, spring-flowering perennial typically found in small, patchy populations on rock outcrops. We used a pollinator exclu-sion experiment to confirm reports thatA. canadensishas a well-developed capacity for autonomous selfing resulting fromincomplete protogyny and close proximity of stigmas and anthers during dehiscence. Flowers excluded from pollinators set87% as many seeds per carpel (X ̄61SE57.161.4 seeds) as hand-pollinated flowers (8.161.3 seeds), and seedproduction in unpollinated flowers correlated negatively with the distance between stigmas and anthers (r520.46). Au-tonomous selfing could be potentially valuable in providing reproductive assurance because only 2.760.5 pollen grainswere deposited on each stigma before anther dehiscence, compared to 134.1617.9 pollen grains by the end of antherdehiscence. However, prevention of autonomous selfing by anther removal before dehiscence did not decrease seed set, evenfor plants at low plant densities where outcross pollen may have been in short supply. Emasculated flowers set as manyseeds per carpel (9.360.9) as intact flowers (8.461.1), indicating that sufficient cross pollen is deposited for full seedset. These results do not support the hypothesis that autonomous selfing byA. canadensishas been selected because itprovides reproductive assurance. Lien pérenne : DOI : 10.2307/2446357 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137833
in American Journal of Botany > 85 (7) (07/1998) . - 919-924Eckert, Christopher George (1960-), Schaefer, A. 1998 Does self-pollination provide reproductive assurance in Aquilegia canadensis (Ranunculaceae)? American Journal of Botany, 85(7): 919-924.Documents numériques
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Article (1998)URL
Titre : Effect of population size on the mating system in a self-compatible, autogamous plant, Aquilegia canadensis (Ranunculaceae) Type de document : Imprimé Auteurs : Matthew B. Routley ; Katherine Mavraganis ; Christopher George Eckert (1960-) Année de publication : 1999 Article en page(s) : 518-528 Langues : Français (fre) Mots-clés : Aquilegia sp. Résumé : In self-compatible plants, small populations may experience reduced outcrossing owing to decreased pollinator visitation and mate availability. We examined the relation between outcrossing and population size in eastern Ontario populations of Aquilegia canadensis. Experimental pollinations showed that the species is highly self-compatible, and can achieve full seed-set in the absence of pollinators via automatic self-pollination. We estimated levels of outcrossing (t) and parental inbreeding coefficients (F) from allozyme variation in naturally pollinated seed families for 10 populations ranging in size from 32 to 750 reproductive individuals. The proportion of seeds produced through outcrossing was generally low (mean = 0.29 ± 0.02 SE) and varied widely among populations (range = 0.00–0.83). Accordingly, estimates of F were large (mean = 0.26 ± 0.05) and significantly greater than zero in seven populations. As expected, four small populations (N < 40) outcrossed less (0.17 ± 0.03) than six large populations (N > 90; 0.38 ± 0.03). However, parental plants were not significantly more inbred in small than large populations (P= 0.18). There was no difference in the germination of seeds from hand self- and cross-pollinations. However, population genetic estimates of inbreeding depression for survival expressed from seed to reproductive maturity were very high (mean δ = 1 − relative fitness of selfed seed = 0.88 ± 0.14). The combination of self-compatibility and automatic self-pollination makes the mating system of A. canadensis sensitive to variation in ecological factors that affect the likelihood of cross-pollination. Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137834
in Heredity > 82 (5) (05/1999) . - 518-528Routley, Matthew B., Mavraganis, Katherine, Eckert, Christopher George (1960-) 1999 Effect of population size on the mating system in a self-compatible, autogamous plant, Aquilegia canadensis (Ranunculaceae). Heredity, 82(5): 518-528.Documents numériques
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article (1999)Adobe Acrobat PDF
Titre : Effects of floral morphology and display on outcrossing in Blue Columbine, Aquilegia caerulea (Ranunculaceae) Type de document : Imprimé Auteurs : J. Brunet ; Christopher George Eckert (1960-) Année de publication : 1998 Article en page(s) : 596-606 Langues : Anglais (eng) Mots-clés : Aquilegia sp. Lien pérenne : DOI : 10.1046/j.1365-2435.1998.00231.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137832
in Functional Ecology > 12 (4) (1998) . - 596-606Brunet, J., Eckert, Christopher George (1960-) 1998 Effects of floral morphology and display on outcrossing in Blue Columbine, Aquilegia caerulea (Ranunculaceae). Functional Ecology, 12(4): 596-606.Documents numériques
Article (1998)URL
Titre : Experimental analysis of protogyny in Aquilegia canadensis (Ranunculaceae) Type de document : Imprimé Auteurs : Steven R. Griffin ; Katherine Mavraganis ; Christopher George Eckert (1960-) Année de publication : 2000 Article en page(s) : 1246-1256 Langues : Anglais (eng) Mots-clés : Aquilegia sp. Aquilegia canadensis Résumé : Dichogamy is very common in flowering plants and is widely thought to reduce pollen-pistil interference, especially self-pollination. Yet, the functional significance of dichogamy has rarely been studied. We investigated the nature and functioning of dichogamy in eastern Ontario populations of Aquilegia canadensis, a highly selfing columbine previously described as protogynous. We then manipulated flowers to determine whether increased protogyny would reduce self-fertilization. Contrary to previous reports, A. canadensis is not dichogamous. Controlled pollinations in a greenhouse showed that pollen tubes generally begin to develop after anther dehiscence. Although stigmas can collect pollen early in floral development, naturally pollinated flowers collected from four populations had few pollen grains on stigmas and almost no pollen tubes in styles until after anther dehiscence. Limited pollen deposition before anther dehiscence was also associated with low nectar availability and limited sepal expansion. Because inbreeding depression is strong in this species, selection may favor increased protogyny if it reduces selfing. We tested this hypothesis by comparing the level of selfing in flowers rendered protogynous by the removal of the first 19 (of 39) anthers to develop, with nonprotogynous control flowers. Contrary to expectations, protogyny did not reduce selfing. Our results emphasize the importance of detailed field observations and manipulative experiments in understanding the nature and functional significance of dichogamy. Lien pérenne : DOI : 10.2307/2656717 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137835
in American Journal of Botany > 87 (9) (07/2000) . - 1246-1256Griffin, Steven R., Mavraganis, Katherine, Eckert, Christopher George (1960-) 2000 Experimental analysis of protogyny in Aquilegia canadensis (Ranunculaceae). American Journal of Botany, 87(9): 1246-1256.Documents numériques
article (2000)URLThe loss of sex in clonal plants / Christopher George Eckert (2002)
Titre : The loss of sex in clonal plants Type de document : Tiré à part de revue Auteurs : Christopher George Eckert (1960-) Année de publication : 2002 Importance : 501-520 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Régime et stratégie de reproduction (allogamie, autogamie, apomixie, reproduction asexué) Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=131027 Eckert, Christopher George (1960-) 2002 The loss of sex in clonal plants. Evolutionary Ecology Research, 15 : 501-520.Exemplaires (1)
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