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Luis Santamaria - One of the best experts on this subject based on the ideXlab platform.
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Long Corollas as nectar barriers in Lonicera implexa: interactions between Corolla tube length and nectar volume
Evolutionary Ecology, 2015Co-Authors: Amparo Lázaro, Clara Vignolo, Luis SantamariaAbstract:Long Corollas are a classical example of nectar barriers, because they prevent undesired visitors from consuming the reward intended for more effective pollinators. As the investment in nectar barriers increases, flower attractiveness and nectar rewards may also increase to maintain loyal visitation of most effective pollinators; and flowers may become more prone to nectar robbing. We evaluated the effect of nectar barriers (Corolla tube length), two related traits (nectar volume and upper lip size) and the associated risk of nectar robbing, on the fecundity of Lonicera implexa plants from three populations differing in the abundance of its most efficient pollinator, the hummingbird hawkmoth Macroglossum stellatarum. Corolla tube length varied most among individuals within populations (45–46 % of total variance) and inflorescences within individuals (23–32 %), and showed little variation among populations (0.2–11 %). Longer Corolla tubes were always associated with larger nectar volumes and larger upper lips, although the strength of the relationships varied across populations and years. Robbing frequency increased with Corolla tube length, decreased with nectar volume and upper lip size, and its weak effects on fecundity were predominantly positive. Plant fecundity peaked at two different optima: long Corollas with little nectar and short Corollas with abundant nectar. However, the exact shape of the interaction between Corolla length and nectar volume, as well as the combination of traits showing the highest fecundity, differed between populations and years. This variation could be explained by among-population differences in pollinator assemblages, and inter-annual changes in resources dedicated to reproduction. Our study shows that large nectar volumes can modulate the effect of Corolla length as a nectar barrier, and that the combination of these two traits that maximises fecundity may be related to the identity of pollinators within each population.
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resource competition character displacement and the evolution of deep Corolla tubes
The American Naturalist, 2007Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:It is normally thought that deep Corolla tubes evolve when the plant's successful reproduction is contingent on having a Corolla tube longer than the tongue of the flower's pollinators. Combining optimal foraging theory and quantitative genetics in a spatially explicit, individual-based model, we show that flowers with long Corolla tubes can alternatively evolve because they promote resource partitioning among nectar feeders and increase the probability of conspecific pollen transfer. When there is competition for resources, long-tongued flower visitors feed preferentially at deep flowers and short-tongued visitors at shallow flowers. Both plant species thus benefit when the depths of their Corollas are so different that each flower visitor specializes on one species. Resource competition can promote the evolution of deep Corollas despite the presence of significant amounts of noise, such as deviations from optimal foraging behavior due to perceptual errors or temporal fluctuations in the relative abundance of competing pollinator species. Our results can explain the evolution of long Corollas in a number of systems that do not conform to the traditional view.
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resource competition character displacement and the evolution of deep Corolla tubes
The American Naturalist, 2007Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:Abstract: It is normally thought that deep Corolla tubes evolve when the plant’s successful reproduction is contingent on having a Corolla tube longer than the tongue of the flower’s pollinators. Combining optimal foraging theory and quantitative genetics in a spatially explicit, individual‐based model, we show that flowers with long Corolla tubes can alternatively evolve because they promote resource partitioning among nectar feeders and increase the probability of conspecific pollen transfer. When there is competition for resources, long‐tongued flower visitors feed preferentially at deep flowers and short‐tongued visitors at shallow flowers. Both plant species thus benefit when the depths of their Corollas are so different that each flower visitor specializes on one species. Resource competition can promote the evolution of deep Corollas despite the presence of significant amounts of noise, such as deviations from optimal foraging behavior due to perceptual errors or temporal fluctuations in the relati...
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models of optimal foraging and resource partitioning deep Corollas for long tongues
Behavioral Ecology, 2006Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:We model the optimal foraging strategies for 2 nectarivore species, differing in the length of their proboscis, that exploit the nectar provided by 2 types of flowers, differing in the depths of their Corollas. When like flowers appear in clumps, nectarivores must decide whether to forage at a patch of deep or shallow flowers. If nectarivores forage optimally, at least one flower type will be used by a single nectarivore species. Long-tongued foragers will normally visit deep flowers and short-tongued foragers shallow flowers, although extreme asymmetries in metabolic costs may lead to the opposite arrangement. When deep and shallow flowers are randomly interspersed, nectarivores must decide, on encounter with a flower, whether to collect its nectar or continue searching. At low nectarivore densities, the optimal strategy involves exploiting every encountered flower; however, as nectarivore densities increase and resources become scarce, long-tongued individuals should start concentrating on deep flowers and short-tongued individuals on shallow flowers. Therefore, regardless of the spatial distribution of flowers, Corolla depth can determine which nectarivore species exploit the nectar from each flower type in a given community. It follows that Corolla elongation can evolve as a means to keep nectar thieves at bay if short-tongued visitors are less efficient pollinators than long-tongued visitors. Copyright 2006.
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Models of optimal foraging and resource partitioning: deep Corollas for long tongues
2026Co-Authors: Miguel A. Rodríguez-gironés, Luis SantamariaAbstract:We model the optimal foraging strategies for 2 nectarivore species, differing in the length of their proboscis, that exploit the nectar provided by 2 types of flowers, differing in the depths of their Corollas. When like flowers appear in clumps, nectarivores must decide whether to forage at a patch of deep or shallow flowers. If nectarivores forage optimally, at least one flower type will be used by a single nectarivore species. Long-tongued foragers will normally visit deep flowers and short-tongued foragers shallow flowers, although extreme asymmetries in metabolic costs may lead to the opposite arrangement. When deep and shallow flowers are randomly interspersed, nectarivores must decide, on encounter with a flower, whether to collect its nectar or continue searching. At low nectarivore densities, the optimal strategy involves exploiting every encountered flower; however, as nectarivore densities increase and resources become scarce, long-tongued individuals should start concentrating on deep flowers and short-tongued individuals on shallow flowers. Therefore, regardless of the spatial distribution of flowers, Corolla depth can determine which nectarivore species exploit the nectar from each flower type in a given community. It follows that Corolla elongation can evolve as a means to keep nectar thieves at bay if short-tongued visitors are less efficient pollinators than long-tongued visitors. Copyright 2006.competition; habitat selection; nectar concealment
Miguel A Rodriguezgirones - One of the best experts on this subject based on the ideXlab platform.
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divergent pollination system and morph dependent effects of Corolla length on inaccuracy of reciprocity and reproductive success of a distylous species of rubiaceae
Acta Botanica Brasilica, 2021Co-Authors: Alessandra Ribeiro Pinto, Miguel A Rodriguezgirones, Marina Muniz Moreira, Leandro FreitasAbstract:ABSTRACT Intraspecific floral variations may affect the degree of generalization and efficacy of pollinators, with consequences for plant reproductive success. Such effects could be greater for heterostylous plants because morphological variation can alter reciprocity between morphs. We evaluated the frequency, composition, and efficacy of pollinators, and the reciprocity (measured by population inaccuracy) of Psychotria nuda, a distylous species of Rubiaceae, in a montane forest. Moreover, we assessed the effects of Corolla length on reciprocity and reproductive success. We recorded eighteen species of floral visitors, belonging to four functional groups. The frequency of visits differed among groups with butterflies being the most frequent visitors, in contrast to hummingbird-pollinated lowland populations. This difference did not affect reproductive success, since fruit set was similar between these populations. The total population inaccuracy was 21.56 mm2, with inaccuracy of low organs being higher (12.03 mm²) than that of high organs (9.53 mm²). Floral traits may have different effects on the reproductive success of morphs of distylous species; the Corolla length of P. nuda only affected the reproductive success of short-styled flowers. Large Corollas showed greater reproductive success and lower individual inaccuracies for this morph, indicating compensation for the effects of imperfect reciprocal herkogamy on reproductive success.
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resource competition character displacement and the evolution of deep Corolla tubes
The American Naturalist, 2007Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:Abstract: It is normally thought that deep Corolla tubes evolve when the plant’s successful reproduction is contingent on having a Corolla tube longer than the tongue of the flower’s pollinators. Combining optimal foraging theory and quantitative genetics in a spatially explicit, individual‐based model, we show that flowers with long Corolla tubes can alternatively evolve because they promote resource partitioning among nectar feeders and increase the probability of conspecific pollen transfer. When there is competition for resources, long‐tongued flower visitors feed preferentially at deep flowers and short‐tongued visitors at shallow flowers. Both plant species thus benefit when the depths of their Corollas are so different that each flower visitor specializes on one species. Resource competition can promote the evolution of deep Corollas despite the presence of significant amounts of noise, such as deviations from optimal foraging behavior due to perceptual errors or temporal fluctuations in the relati...
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resource competition character displacement and the evolution of deep Corolla tubes
The American Naturalist, 2007Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:It is normally thought that deep Corolla tubes evolve when the plant's successful reproduction is contingent on having a Corolla tube longer than the tongue of the flower's pollinators. Combining optimal foraging theory and quantitative genetics in a spatially explicit, individual-based model, we show that flowers with long Corolla tubes can alternatively evolve because they promote resource partitioning among nectar feeders and increase the probability of conspecific pollen transfer. When there is competition for resources, long-tongued flower visitors feed preferentially at deep flowers and short-tongued visitors at shallow flowers. Both plant species thus benefit when the depths of their Corollas are so different that each flower visitor specializes on one species. Resource competition can promote the evolution of deep Corollas despite the presence of significant amounts of noise, such as deviations from optimal foraging behavior due to perceptual errors or temporal fluctuations in the relative abundance of competing pollinator species. Our results can explain the evolution of long Corollas in a number of systems that do not conform to the traditional view.
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models of optimal foraging and resource partitioning deep Corollas for long tongues
Behavioral Ecology, 2006Co-Authors: Miguel A Rodriguezgirones, Luis SantamariaAbstract:We model the optimal foraging strategies for 2 nectarivore species, differing in the length of their proboscis, that exploit the nectar provided by 2 types of flowers, differing in the depths of their Corollas. When like flowers appear in clumps, nectarivores must decide whether to forage at a patch of deep or shallow flowers. If nectarivores forage optimally, at least one flower type will be used by a single nectarivore species. Long-tongued foragers will normally visit deep flowers and short-tongued foragers shallow flowers, although extreme asymmetries in metabolic costs may lead to the opposite arrangement. When deep and shallow flowers are randomly interspersed, nectarivores must decide, on encounter with a flower, whether to collect its nectar or continue searching. At low nectarivore densities, the optimal strategy involves exploiting every encountered flower; however, as nectarivore densities increase and resources become scarce, long-tongued individuals should start concentrating on deep flowers and short-tongued individuals on shallow flowers. Therefore, regardless of the spatial distribution of flowers, Corolla depth can determine which nectarivore species exploit the nectar from each flower type in a given community. It follows that Corolla elongation can evolve as a means to keep nectar thieves at bay if short-tongued visitors are less efficient pollinators than long-tongued visitors. Copyright 2006.
Grande Allende, José Ramón - One of the best experts on this subject based on the ideXlab platform.
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Convolvulaceae neotropicae novae vel minus cognitae III: Jacquemontia austiniana J.R.Grande sp. nov. (Convolvulaceae), una especie nueva de la Guayana venezolana
'Editorial CSIC', 2019Co-Authors: Grande Allende, José RamónAbstract:As a part of a taxonomic update of the family Convolvulaceae Juss. for Guayana Shield, the species Jacquemontia austiniana J.R.Grande sp. nov., is described and illustrated as new to science. This species is characterized by its linear-subulate bract, ovate-lanceolate external sepals, conspicuously acuminate, villose, with the margins ciliate, and a relatively large and infundibuliform Corolla. To date, this is the only species of Jacquemontia Choisy endemic to the Guayana Shield; its relationships within the genus are still to be elucidated.Como parte de la actualización taxonómica de la familia Convolvulaceae Juss. para el escudo guayanés, se describe e ilustra Jacquemontia austiniana J.R.Grande sp. nov., como nueva para la ciencia. Esta especie se caracteriza por tener brácteas linear-subuladas, sépalos externos ovado-lanceolados, conspicuamente acuminados, vilosos y con el margen ciliado, además de una corola infundibuliforme y relativamente grande. Hasta el momento, esta es la única especie de Jacquemontia Choisy endémica del escudo guayanés. Sus relaciones dentro del género quedan aún por dilucidar
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"Convolvulaceae neotropicae novae vel minus cognitae" III: "Jacquemontia austiniana" J.R.Grande sp. nov. ("Convolvulaceae"), a new species from the Venezuelan Guayana
2019Co-Authors: Grande Allende, José RamónAbstract:As a part of a taxonomic update of the family Convolvulaceae Juss. for Guayana Shield, the species Jacquemontia austiniana J.R.Grande sp. nov., is described and illustrated as new to science. This species is characterized by its linear-subulate bract, ovate-lanceolate external sepals, conspicuously acuminate, villose, with the margins ciliate, and a relatively large and infundibuliform Corolla. To date, this is the only species of Jacquemontia Choisy endemic to the Guayana Shield; its relationships within the genus are still to be elucidated.Como parte de la actualización taxonómica de la familia Convolvulaceae Juss. para el escudo guayanés, se describe e ilustra Jacquemontia austiniana J.R.Grande sp. nov., como nueva para la ciencia. Esta especie se caracteriza por tener brácteas linear-subuladas, sépalos externos ovado-lanceolados, conspicuamente acuminados, vilosos y con el margen ciliado, además de una corola infundibuliforme y relativamente grande. Hasta el momento, esta es la única especie de Jacquemontia Choisy endémica del escudo guayanés. Sus relaciones dentro del género quedan aún por dilucidar
Vincent M Eckhart - One of the best experts on this subject based on the ideXlab platform.
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do hermaphrodites of gynodioecious phacelia linearis hydrophyllaceae trade off seed production to attract pollinators
Biological Journal of The Linnean Society, 1993Co-Authors: Vincent M EckhartAbstract:Abstract Sexual selection theory predicts that hermaphroditic plants might trade off seed production to attract pollinators. This paper reports a test of this prediction in gynodioecious Phacelia linearis (Hydrophyllaceae), a species in which attractiveness to pollinators increases with Corolla diameter. The relationship between Corolla diameter and seed production was determined in three natural and three experimental populations. Phenotypic selection analysis was used, with lifetime seed production as a surrogate for fitness. Negative directional selection was expected on hermaphrodite Corolla diameter. No directional selection (but possibly stabilizing selection) was expected on Corolla diameter in females, which have smaller Corollas than hermaphrodites. Shoot biomass and flowering time were included in selection analyses so that the effects of Corolla size could be assessed independently of these correlated characters. A parent-offspring study of the quantitative genetics of these characters also was performed. High seed production was associated with large shoot biomass (especially in natural populations) and early flowering (especially in experimental populations). The effect of hermaphrodite Corolla size on seed production was not as predicted. Directional selection on hermaphrodite Corolla diameter was generally positive. Directional selection on female Corolla diameter was relatively weak and variable; stabilizing selection was found in one population. Most of the phenotypic selection on Corolla diameter was caused by its (environmental) correlation with shoot biomass. Although these findings do not support the hypothesis that hermaphrodites trade off seed production to attract pollinators, a cautious interpretation is warranted. In one natural population, insect herbivory generated positive covariance between hermaphrodite Corolla diameter and seed number, leading to a spurious estimate of positive directional selection for Corolla diameter. Other, undetected sources of positive covariance between Corolla size and seed production also might have obscured the expected tradeoff. Corolla diameter was found to be heritable, but shoot biomass and flowering time were not. The genetic correlation between hermaphrodite Corolla diameter and female Corolla diameter was positive and significant, but it was significantly less than 1, so Corolla size could evolve independently in the two genders.
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the genetics of gender and the effects of gender on floral characters in gynodioecious phacelia linearis hydrophyllaceae
American Journal of Botany, 1992Co-Authors: Vincent M EckhartAbstract:The evolution of gynodioecy depends in part on the location (nucleus or cytoplasm) ofgender-determining genes. Characters genetically correlated with gender also can be important in the evolution of this sexual system. For example, gender differences in the costs of flowers affect the potential for resource compensation by females for the loss of male function. This paper reports the genetics of gender and the nature of secondary sex characters of flowers in Phacelia linearis (Hydrophyllaceae), a gynodioecious annual in which females exhibit substantial compensation. A single nuclear gene has a major effect on gender, recessive homozygotes being male-sterile, but not all the data can be explained by this or other simple inheritance models. In nature, hermaphrodites have wider Corollas than females and begin to flower slightly later than females. In a common environment, gender effects on Corolla size are modified by genetic background and/or maternal effects. Hermaphrodite flowers have 15% greater dry biomass than female flowers, but similar ovule number and nectar sugar production. Hermaphrodite and female flowers differ in the linear dimensions and biomass allocation of several floral organs. In particular, the androecia and Corollas of female flowers are smaller than those of hermaphrodite flowers, both in absolute terms and relative to the size of the rest of the flower. Corolla size reduction could be an important source of resources for compensation by females. The sexual system in which hermaphroditic and female individuals coexist is called gynodioecy (Darwin, 1877). In theory, under most modes of nuclear gender inheritance, the expected lifetime seed production of females
Alexander Vainstein - One of the best experts on this subject based on the ideXlab platform.
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chrc encoding a chromoplast specific carotenoid associated protein is an early gibberellic acid responsive gene
Journal of Biological Chemistry, 1997Co-Authors: Michael Vishnevetsky, Mariana Ovadis, Hanan Itzhaki, Alexander VainsteinAbstract:Abstract CHRC, a Corolla-specific carotenoid-associated protein, is a major component of carotenoid-lipoprotein complexes inCucumis sativus chromoplasts. Using an in vitroflower bud culture system that mimics in vivo flower development, CHRC mRNA levels in Corollas were shown to be specifically up-regulated by gibberellic acid. The response to gibberellic acid was very rapid (within 20 min) and insensitive to protein synthesis inhibition by cycloheximide. Abscisic acid, known to antagonize gibberellin in many developmental systems, strongly down-regulated CHRC mRNA levels. The gibberellin synthesis inhibitor paclobutrazol exhibited a similar negative effect on CHRC expression. Inclusion of exogenous gibberellic acid into the in vitro bud culture system with the paclobutrazol not only prevented the CHRC mRNA down-regulation, it up-regulated transcript accumulation to the level of gibberellic acid-treated Corollas. CHRC mRNA accumulation in response to gibberellic acid displayed a dose-dependent increase up to 10−4 m gibberellic acid. The up-regulation could be detected with as little as 10−7 m gibberellic acid. Based on these data, we suggest thatCHRC is the first structural gene identified to date whose expression is regulated by gibberellic acid in a primary fashion. The critical role of the rapid response of CHRC to gibberellic acid in aiding carotenoid sequestration while preserving chromoplast structural organization is discussed.
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isolation and regulation of accumulation of a minor chromoplast specific protein from cucumber Corollas
Plant Physiology, 1997Co-Authors: Yael Libalweksler, Michael Vishnevetsky, Mariana Ovadis, Alexander VainsteinAbstract:The differentiation of chloroplasts to chromoplasts in cucumber (Cucumis sativus L.) Corollas parallels flower development. Chromoplast biogenesis involves chlorophyll degradation, carotenoid accumulation, and the appearance of a new set of proteins. To study factors involved in chromoplast biogenesis in floral tissues, a minor (in abundance) protein of about 14 kD, CHRD (chromoplast protein D), was isolated from cucumber Corolla chromoplasts. Immunological characterization revealed that the protein is chromoplast-specific and that its steady-state level in Corollas increases in parallel to flower development. The protein was not detected in cucumber leaves or fruits. Immunological analysis of Corollas and fruits from a variety of other plants also did not reveal cross-reactivity with the CHRD protein antisera. Using an in vitro bud culture system, we analyzed the effect of phytohormones on CHRD expression. Gibberellic acid rapidly enhanced, whereas paclobutrazol down-regulated, the steady-state level of CHRD. Ethylene also down-regulated the protein9s steady-state level. It is suggested that hormonal control of chromoplastogenesis is tightly regulated at the tissue/organ level and that mainly developmental signals control carotenoid accumulation in nonphotosynthetic tissues.
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chromoplast biogenesis in cucumis sativus Corollas rapid effect of gibberellin a3 on the accumulation of a chromoplast specific carotenoid associated protein
Plant Physiology, 1994Co-Authors: Alexander Vainstein, A H Halevy, Iris Smirra, Michael VishnevetskyAbstract:The development of cucumber (Cucumis sativus L.) Corollas is accompanied by the accumulation of chromoplasts. In mature Corollas, chromoplasts, but no chloroplasts, were detected by electron microscopy. Chlorophyll was also undetectable in Corollas at anthesis. The contents of carotenoids and a carotenoid-associated, chromoplast-specific, 35-kD protein in Corollas increased in parallel with flower development, peaking concomitantly at anthesis. The involvement of phytohormones and light in the regulation of their expression was studied. When gibberellin A3 (GA3) was added to an in vitro bud culture system, accumulation of both carotenoids and the 35-kD protein was markedly enhanced. The specific up-regulation of the 35-kD protein was very rapid: after only 2 h of culture, increased levels were detected in GA3-treated versus untreated Corollas. During this period, Corolla fresh weight and total protein and carotenoid contents remained unchanged. Inclusion of abscisic acid in the culture medium counteracted the effect of GA3. Accumulation of the 35-kD protein was also enhanced when flower buds on plants were sprayed with GA3 or etiolated.