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José Ramón Obeso - One of the best experts on this subject based on the ideXlab platform.
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dimorfismo sexual en el acebo Ilex aquifolium coste de la reproduccion seleccion sexual o diferenciacion fisiologica
Revista Chilena de Historia Natural, 2002Co-Authors: José Ramón Obeso, Rubén RetuertoAbstract:Se examina la importancia de tres hipotesis que pueden explicar la existencia de dimorfismo sexual en caracteres secundarios (tamano) en arbol dioico Ilex aquifolium (Aquifoliaceae): coste de la reproduccion, competencia entre machos y diferenciacion fisiologica entre sexos. Para ello se presenta una sintesis de trabajos publicados junto con nuevos resultados de tipo observacional y experimental. Durante la floracion los machos invirtieron el triple de carbono y el doble de nitrogeno que las hembras. En la fructificacion, los arboles hembras invirtieron 10 veces mas que los machos en carbono, pero solo cinco veces mas en nitrogeno. No se encontraron diferencias entre sexos en la dinamica foliar y las diferencias en el crecimiento de las ramas fueron dependientes del contexto, aunque en general crecieron mas en los machos. En periodos de tiempo largos, 10-30 anos, el grosor medio de los anillos de crecimiento de los arboles fue superior en los machos. Las ramas en las que se interrumpio la reproduccion eliminando los brotes florales crecieron significativamente mas que aquellas que maduraron frutos. Se encontraron diferencias entre machos en la produccion de granos de polen por flor. La realizacion de todos los cruces posibles entre cinco machos y cinco hembras demostro fuertes efectos maternos en la fecundidad, pero no hubo diferencias entre machos en la probabilidad de dejar descendencia. Existen diferencias fisiologicas entre sexos en condiciones de baja luminosidad; asi la eficiencia de la fotosintesis (evaluada como Fv' / Fm') fue mayor en las hembras y por el contrario, los machos fueron mas eficientes en el uso del agua (evaluado mediante discriminacion isotopica del carbono). Finalmente se discute la importancia de las hipotesis consideradas para explicar estos resultados
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Gender, light and water effects in carbon isotope discrimination, and growth rates in the dioecious tree Ilex aquifolium
Functional Ecology, 2000Co-Authors: Rubén Retuerto, B. Fernandez Lema, S. Rodriguez Roiloa, José Ramón ObesoAbstract:1. Detailed understanding of the specific physiology of sexes in dioecious species is required to explain patterns in gender dimorphism. Under controlled-environment conditions we tested the hypothesis that sexes of the dioecious tree holly Ilex aquifolium L. (Aquifoliaceae) differed in growth and long-term potential water-use efficiency, as measured by carbon isotope discrimination (Δ13C), and that these differences were dependent on the environmental context. 2. Patterns of response in Δ13C to the various combinations of light and water were gender-specific. Under more xeric conditions, females maintained significantly higher Δ13C than males. 3. Female plants exhibited significantly greater relative diameter growth rates than male plants. 4. As expected, Δ13C significantly increased with decreasing irradiance, and decreased with increasing limitation in water supply. Light and water effects were not independent, with a more pronounced drought effect in decreasing leaf Δ13C under unshaded than under shaded conditions. 5. Our results suggest that between-sex differences in physiology are context-dependent. Future studies attempting to assess gender dimorphism should take more account of gender-specific interactions with the environment. Gender-specific efficiency in water use could play a decisive role in explaining gender differences in growth and ecological interactions.
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Sex ratios, size distributions, and sexual dimorphism in the dioecious tree Ilex aquifolium (Aquifoliaceae).
American journal of botany, 1998Co-Authors: José Ramón Obeso, Manuel Alvarez‐santullano, Rubén RetuertoAbstract:Sex ratio and sexual dimorphism in physiology and growth were studied in the dioecious tree Ilex aquifolium at two localities in northern Spain. Genet sex ratio was significantly male biased in one locality but not in the other. However, ramet and flowering ramet sex ratios were male biased at both study sites. Males had significantly thicker main trunks than females in one locality and produced more ramets in the other. Growth rate, estimated from mean width of annual rings, did not differ between localities, but males produced wider rings than females at both sites. Mean annual growth rates over the last 10, 20, and 30 yr were significantly higher for males. Measurements of chlorophyll fluorescence indicated that the efficiency of photosynthesis of leaves on nonfruiting branches of females was higher than for leaves on branches of male plants under low-light conditions, though not under saturating-light conditions. Efficiency of photosynthesis was significantly lower on fruiting branches of female plants than on nonfruiting branches. We discuss whether the observed between-sex differences are attributable to the higher cost of reproduction in females and/or to pollen competition.
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Patterns of variation in Ilex aquifolium fruit traits related to fruit consumption by birds and seed predation by rodents
Écoscience, 1998Co-Authors: José Ramón ObesoAbstract:The drupes of Ilex aquifolium contain up to four pyrenes, but brood size reduction by both pyrene number reduction and/or seed abortion producing blank pyrenes affected 2/3 of fruit production. The...
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Effects of defoliation and girdling on fruit production in Ilex aquifolium
Functional Ecology, 1998Co-Authors: José Ramón ObesoAbstract:1. The effects of defoliation and girdling on fruit production in European holly Ilex aquifolium were studied in a northern Spanish population. Three defoliation treatments (control, 50% and 100% leaf removal) were applied at branch level in 10 trees. Six branches were used per treatment in each tree and half of these branches were girdled (a ring of bark and cambium was removed from the branch base). 2. Leaf removal from ungirdled branches had little effect on fruit set, fruit production and reproductive allocation at branch level. However, these variables decreased as the extent of defoliation increased on girdled branches. 3. Fruit production in undefoliated branches did not differ between girdled and ungirdled branches, showing that girdled branches were autonomous for fruit production when undamaged. Mean fruit mass of girdled-100% defoliated branches averaged 8% of fruit mass produced by control branches. 4. Fruit production of ungirdled-100% defoliated branches did not differ from control branches, showing the importance of resource importation from other branches. Hence the branches may be regarded as only partially autonomous for fruit production. 5. Fruit production of girdled-50% defoliated branches was 42% of fruit production of control branches, while ungirdled-50% defoliated branches amounted to 70% of controls. These results also demonstrated resource importation but did not support the existence of photosynthetic compensatory mechanisms. 6. The ability of resource importation developed by fruiting branches might be a mechanism to reduce the effect of reproductive costs in this species.
Samuel J. Stellpflug - One of the best experts on this subject based on the ideXlab platform.
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Holiday plants with toxic misconceptions.
Western Journal of Emergency Medicine, 2012Co-Authors: Zabrina N. Evens, Samuel J. StellpflugAbstract:Several plants are used for their decorative effect during winter holidays. This review exploresthe toxic reputation and proposed management for exposures to several of those, namelypoinsettia (Euphorbia pulcherrima), English holly (Ilex aquifolium), American holly (Ilex opaca),bittersweet (Solanum dulcamara), Jerusalem cherry (Solanum pseudocapsicum), Americanmistletoe (Phoradendron serotinum), and European mistletoe (Viscum album). [West J Emerg Med.2012;13(6):538-542]
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Holiday Plants with Toxic Misconceptions
Western Journal of Emergency Medicine, 2012Co-Authors: Zabrina N. Evens, Samuel J. StellpflugAbstract:Several plants are used for their decorative effect during winter holidays. This review explores the toxic reputation and proposed management for exposures to several of those, namely poinsettia (Euphorbia pulcherrima), English holly (Ilex aquifolium), American holly (Ilex opaca), bittersweet (Solanum dulcamara), Jerusalem cherry (Solanum pseudocapsicum), American mistletoe (Phoradendron serotinum), and European mistletoe (Viscum album).
Zabrina N. Evens - One of the best experts on this subject based on the ideXlab platform.
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Holiday plants with toxic misconceptions.
Western Journal of Emergency Medicine, 2012Co-Authors: Zabrina N. Evens, Samuel J. StellpflugAbstract:Several plants are used for their decorative effect during winter holidays. This review exploresthe toxic reputation and proposed management for exposures to several of those, namelypoinsettia (Euphorbia pulcherrima), English holly (Ilex aquifolium), American holly (Ilex opaca),bittersweet (Solanum dulcamara), Jerusalem cherry (Solanum pseudocapsicum), Americanmistletoe (Phoradendron serotinum), and European mistletoe (Viscum album). [West J Emerg Med.2012;13(6):538-542]
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Holiday Plants with Toxic Misconceptions
Western Journal of Emergency Medicine, 2012Co-Authors: Zabrina N. Evens, Samuel J. StellpflugAbstract:Several plants are used for their decorative effect during winter holidays. This review explores the toxic reputation and proposed management for exposures to several of those, namely poinsettia (Euphorbia pulcherrima), English holly (Ilex aquifolium), American holly (Ilex opaca), bittersweet (Solanum dulcamara), Jerusalem cherry (Solanum pseudocapsicum), American mistletoe (Phoradendron serotinum), and European mistletoe (Viscum album).
Richard A. Ennos - One of the best experts on this subject based on the ideXlab platform.
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Chloroplast DNA diversity of the dioecious European tree Ilex aquifolium L. (English holly).
Molecular ecology, 2003Co-Authors: S. Rendell, Richard A. EnnosAbstract:Variation in the chloroplast genome of Ilex aquifolium (English holly), a dioecious evergreen tree native to south, west and central Europe, was analysed using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLPs) and microsatellites. Differentiation between populations was high (GST = 0.595) and evidence for phylogeographical structure was detected (NST = 0.697, significantly higher than GST). Two chloroplast lineages were inferred originating from putative glacial refugia in southern Europe (Iberia, Italy and possibly the Balkans). The GST value was higher than reported for endozoochorous hermaphrodite species and for anemochorous dioecious species investigated over a similar geographical scale. It appears that dioecy has contributed to strong differentiation between refugia and that this has been maintained following postglacial recolonization as a result of limited seed flow. Palynological records for I. aquifolium are poor, thus these results give an important insight into patterns of glacial isolation and postglacial recolonization of this species.
Rubén Retuerto - One of the best experts on this subject based on the ideXlab platform.
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dimorfismo sexual en el acebo Ilex aquifolium coste de la reproduccion seleccion sexual o diferenciacion fisiologica
Revista Chilena de Historia Natural, 2002Co-Authors: José Ramón Obeso, Rubén RetuertoAbstract:Se examina la importancia de tres hipotesis que pueden explicar la existencia de dimorfismo sexual en caracteres secundarios (tamano) en arbol dioico Ilex aquifolium (Aquifoliaceae): coste de la reproduccion, competencia entre machos y diferenciacion fisiologica entre sexos. Para ello se presenta una sintesis de trabajos publicados junto con nuevos resultados de tipo observacional y experimental. Durante la floracion los machos invirtieron el triple de carbono y el doble de nitrogeno que las hembras. En la fructificacion, los arboles hembras invirtieron 10 veces mas que los machos en carbono, pero solo cinco veces mas en nitrogeno. No se encontraron diferencias entre sexos en la dinamica foliar y las diferencias en el crecimiento de las ramas fueron dependientes del contexto, aunque en general crecieron mas en los machos. En periodos de tiempo largos, 10-30 anos, el grosor medio de los anillos de crecimiento de los arboles fue superior en los machos. Las ramas en las que se interrumpio la reproduccion eliminando los brotes florales crecieron significativamente mas que aquellas que maduraron frutos. Se encontraron diferencias entre machos en la produccion de granos de polen por flor. La realizacion de todos los cruces posibles entre cinco machos y cinco hembras demostro fuertes efectos maternos en la fecundidad, pero no hubo diferencias entre machos en la probabilidad de dejar descendencia. Existen diferencias fisiologicas entre sexos en condiciones de baja luminosidad; asi la eficiencia de la fotosintesis (evaluada como Fv' / Fm') fue mayor en las hembras y por el contrario, los machos fueron mas eficientes en el uso del agua (evaluado mediante discriminacion isotopica del carbono). Finalmente se discute la importancia de las hipotesis consideradas para explicar estos resultados
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Gender, light and water effects in carbon isotope discrimination, and growth rates in the dioecious tree Ilex aquifolium
Functional Ecology, 2000Co-Authors: Rubén Retuerto, B. Fernandez Lema, S. Rodriguez Roiloa, José Ramón ObesoAbstract:1. Detailed understanding of the specific physiology of sexes in dioecious species is required to explain patterns in gender dimorphism. Under controlled-environment conditions we tested the hypothesis that sexes of the dioecious tree holly Ilex aquifolium L. (Aquifoliaceae) differed in growth and long-term potential water-use efficiency, as measured by carbon isotope discrimination (Δ13C), and that these differences were dependent on the environmental context. 2. Patterns of response in Δ13C to the various combinations of light and water were gender-specific. Under more xeric conditions, females maintained significantly higher Δ13C than males. 3. Female plants exhibited significantly greater relative diameter growth rates than male plants. 4. As expected, Δ13C significantly increased with decreasing irradiance, and decreased with increasing limitation in water supply. Light and water effects were not independent, with a more pronounced drought effect in decreasing leaf Δ13C under unshaded than under shaded conditions. 5. Our results suggest that between-sex differences in physiology are context-dependent. Future studies attempting to assess gender dimorphism should take more account of gender-specific interactions with the environment. Gender-specific efficiency in water use could play a decisive role in explaining gender differences in growth and ecological interactions.
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Sex ratios, size distributions, and sexual dimorphism in the dioecious tree Ilex aquifolium (Aquifoliaceae).
American journal of botany, 1998Co-Authors: José Ramón Obeso, Manuel Alvarez‐santullano, Rubén RetuertoAbstract:Sex ratio and sexual dimorphism in physiology and growth were studied in the dioecious tree Ilex aquifolium at two localities in northern Spain. Genet sex ratio was significantly male biased in one locality but not in the other. However, ramet and flowering ramet sex ratios were male biased at both study sites. Males had significantly thicker main trunks than females in one locality and produced more ramets in the other. Growth rate, estimated from mean width of annual rings, did not differ between localities, but males produced wider rings than females at both sites. Mean annual growth rates over the last 10, 20, and 30 yr were significantly higher for males. Measurements of chlorophyll fluorescence indicated that the efficiency of photosynthesis of leaves on nonfruiting branches of females was higher than for leaves on branches of male plants under low-light conditions, though not under saturating-light conditions. Efficiency of photosynthesis was significantly lower on fruiting branches of female plants than on nonfruiting branches. We discuss whether the observed between-sex differences are attributable to the higher cost of reproduction in females and/or to pollen competition.
