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Christopher G. Eckert - One of the best experts on this subject based on the ideXlab platform.
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Cryptic self-incompatibility in tristylous Decodon verticillatus (Lythraceae).
American journal of botany, 1997Co-Authors: Christopher G. Eckert, Maryl AllenAbstract:There is growing evidence that many self-compatible plants control the level of self-fertilization with postpollination processes that give a siring advantage to cross pollen over self pollen through ‘‘cryptic self-incompatibility’’ (CSI). Previous marker-gene experiments with self-compatible, tristylous Decodon verticillatus (Lythraceae) have demonstrated a siring advantage to cross pollen, though the extent to which this advantage results from prezygotic discrimination vs. early acting inbreeding depression is not clear. Here, we provide evidence that prezygotic mechanisms are involved in this siring advantage by comparing pollen tube numbers at various times following cross- and self-pollination conducted in a natural population. In the 24 h following pollination, cross pollen yielded almost twice as many pollen tubes at various positions in the style compared to self pollen. After 36 and 48 h, the difference between pollen types had disappeared, suggesting that the advantage to cross pollen results from differences in the rate of pollen germination and/or tube growth rather than pollen tube attrition. Comparison of tube numbers after legitimate vs. illegitimate cross-pollination did not reveal any difference, suggesting that D. verticillatus possesses CSI unrelated to heteromorphic self- and intramorph-incompatibility found in other heterostylous members of the Lythraceae. CSI resulting from differential pollen tube growth may minimize geitonogamous selfing when cross pollen is abundant, while maximizing fecundity when cross pollen is scarce due to local clonal spread.
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Evolutionary consequences of extensive morph loss in tristylous decodon verticillatus (Lythraceae): a shift from tristyly to distyly?
American Journal of Botany, 1996Co-Authors: Christopher G. Eckert, Katherine MavraganisAbstract:The evolution of distyly from tristyly has occurred repeatedly, especially in the Lythraceae. However, the evolutionary forces involved remain unclear since species exhibiting transitional stages between tristyly and distyly have rarely been studied. The self-compatible, wetland perennial Decodon verticillatus (Lythraceae) may provide this transitional variation since populations commonly lack style morphs, particularly the mid-styled (M) morph. In dimorphic populations lacking the M morph, anthers positioned at the mid level in both the long(L) and short-styled (S) morphs have lost their target stigma, setting the stage for either evolutionary repositioning of mid-level anthers to increase pollen export to L and S stigmas, or increased variability in mid-level anther position resulting from relaxed selection. We examined these two hypotheses by comparing floral morphology in eight dimorphic and ten trimorphic populations from throughout the species' range. We found no evidence that loss of the M morph has led to evolutionary modification of mid-level stamens. While mid-level stamens of the S morph were 11.0 ? 4.0% (mean ? 1 SE) longer than those of the L morph in dimorphic populations, divergence in stamen length between morphs occurred to the same extent (10.4 ? 2.0%) in trimorphic populations and cannot be attributed to the absence of the M morph. Analyses of variability using median ratio tests revealed no difference in the variability of mid-level stamen length between dimorphic and trimorphic populations. Mid-level stamens were not more variable than longand short-level stamens within dimorphic populations. The consistent divergence in midlevel stamens between the L and S morphs may reflect morph-specific differences in the optimal position of mid-level anthers for maximizing cross-pollination and avoiding self-fertilization.
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Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)
Heredity, 1996Co-Authors: Christopher G. Eckert, Domenica Manicacci, Spencer C. H. BarrettAbstract:Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)
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Post-pollination mechanisms and the maintenance of outcrossing in self-compatible, tristylous, Decodon verticillatus (Lythraceae)
Heredity, 1994Co-Authors: Christopher G. Eckert, Spencer C. H. BarrettAbstract:Post-pollination mechanisms and the maintenance of outcrossing in self-compatible, tristylous, Decodon verticillatus (Lythraceae)
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The inheritance of tristyly in Decodon verticillatus (Lythraceae)
Heredity, 1993Co-Authors: Christopher G. Eckert, Spencer C. H. BarrettAbstract:The inheritance of tristyly is generally thought to be governed by two diallelic loci, S and M, with complete dominance and epistasis between the loci. Significant departures from the two-locus model have, however, been recently reported in species of Oxalis. This study presents a genetic analysis of tristyly in the eastern North American monotypic perennial Decodon verticillatus (L.) Ell. (Lythraceae). Crosses conducted on plants from six natural populations in Ontario resulted in patterns of segregation consistent with the two-locus model. The L morph is homozygous at both loci (ssmm).Crosses among F1 progeny identified two F1 individuals of the M morph homozygous for the dominant allele at the M locus (ssMM) and an F1 individual of the S morph homozygous for the dominant allele at the S locus (SSmm). Crosses between these genotypes demonstrated epistasis of the S locus over the M locus and produced putative double heterozygotes Sm/sM). Five of these F2 genotypes were both self-fertilized and crossed as pollen donors to individuals of the L morph. Segregation in F3 and backcrossed progenies confirmed the two-locus model and provided no evidence for linkage between the loci. The results support the model of inheritance established for distantly related Lythrum salicaria, suggesting that the genetic control of tristyly may be uniform throughout the Lythraceae.
Spencer C. H. Barrett - One of the best experts on this subject based on the ideXlab platform.
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Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)
Heredity, 1996Co-Authors: Christopher G. Eckert, Domenica Manicacci, Spencer C. H. BarrettAbstract:Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)
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Post-pollination mechanisms and the maintenance of outcrossing in self-compatible, tristylous, Decodon verticillatus (Lythraceae)
Heredity, 1994Co-Authors: Christopher G. Eckert, Spencer C. H. BarrettAbstract:Post-pollination mechanisms and the maintenance of outcrossing in self-compatible, tristylous, Decodon verticillatus (Lythraceae)
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The inheritance of tristyly in Decodon verticillatus (Lythraceae)
Heredity, 1993Co-Authors: Christopher G. Eckert, Spencer C. H. BarrettAbstract:The inheritance of tristyly is generally thought to be governed by two diallelic loci, S and M, with complete dominance and epistasis between the loci. Significant departures from the two-locus model have, however, been recently reported in species of Oxalis. This study presents a genetic analysis of tristyly in the eastern North American monotypic perennial Decodon verticillatus (L.) Ell. (Lythraceae). Crosses conducted on plants from six natural populations in Ontario resulted in patterns of segregation consistent with the two-locus model. The L morph is homozygous at both loci (ssmm).Crosses among F1 progeny identified two F1 individuals of the M morph homozygous for the dominant allele at the M locus (ssMM) and an F1 individual of the S morph homozygous for the dominant allele at the S locus (SSmm). Crosses between these genotypes demonstrated epistasis of the S locus over the M locus and produced putative double heterozygotes Sm/sM). Five of these F2 genotypes were both self-fertilized and crossed as pollen donors to individuals of the L morph. Segregation in F3 and backcrossed progenies confirmed the two-locus model and provided no evidence for linkage between the loci. The results support the model of inheritance established for distantly related Lythrum salicaria, suggesting that the genetic control of tristyly may be uniform throughout the Lythraceae.
Shirley A. Graham - One of the best experts on this subject based on the ideXlab platform.
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Ovary, Fruit, and Seed Morphology of the Lythraceae
International Journal of Plant Sciences, 2014Co-Authors: Shirley A. Graham, Alan GrahamAbstract:Premise of research. The ovary, fruits, and seeds of the Lythraceae present an array of morphological characters that have not been fully explored for their utility in clarifying taxonomic, phylogenetic, and historical biogeographic questions. This study provides a morphological record of ovary, fruit, and seed characters for the family that can be used to address these questions. The seeds, in particular, display diverse adaptations to dispersal and are emphasized in the study. A more complete knowledge of the fruits and seeds of the Lythraceae further promises to aid identification of lythracean fossil fruit and seed remains from late Cretaceous and Cenozoic floras around the world.Methodology. The morphology of alcohol-preserved and softened dried ovaries, fruits, and seeds is described based on hand sections studied using LM. SEM further details the external features of mature seeds of all genera of the family. Selected character states are shown on a previously produced molecular-based phylogeny to e...
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Fossil Records in the Lythraceae
The Botanical Review, 2013Co-Authors: Shirley A. GrahamAbstract:The Lythraceae (Myrtales) are a family of 28 genera and ca. 600 species constituting with the Combretaceae and sister family Onagraceae a major lineage of the Myrtales and including the former Sonneratiaceae, Duabangaceae, Punicaceae, and Trapaceae. The fossil record of the family is extensive and significant new discoveries have been added to the record in recent years. This review provides a vetted summary of fossils attributed to the Lythraceae, their geographic distributions, and their stratigraphic ranges. It anticipates the use of the information to generate robustly dated molecular phylogenies to accurately reconstruct the evolutionary and biogeographic history of the family. Fossils of 44 genera or form genera have been attributed to the Lythraceae; 24 are accepted here as lythracean. Fourteen of the 28 modern genera have fossil representatives: Adenaria, Crenea, Cuphea, Decodon, Duabanga, Lafoensia, Lagerstroemia, Lawsonia, Lythrum, Pemphis, Punica, Sonneratia, Trapa , and Woodfordia . Ten extinct genera are recognized. The most common kinds of fossil remains are seeds and pollen. The only fossil flower confidently accepted in the family is the extinct genus Sahnianthus from the Early Paleocene of India. The oldest confirmed evidence of the Lythraceae is pollen of Lythrum/Peplis from the Late Cretaceous (early Campanian, 82−81 Ma) of Wyoming. Seeds of Decodon from the late Campanian (73.5 Ma) of northern Mexico are next oldest. Sonneratia, Lagerstroemia , and extinct Sahnianthus first appear in the Paleocene of the Indian subcontinent; extinct Hemitrapa fruits first occur in the Paleocene of northwestern North America. Diversification of the Lythraceae occurred primarily during two major periods of global temperature change, during the Paleocene-Eocene Thermal Maximum and from the middle Miocene forward when temperatures decreased markedly and seasonality and dry-adapted vegetation types became more prominent. Fossils of the Lythraceae from South America and Africa are limited in number. The few dates available for South American genera are comparatively young and diversification of the largest genus, Cuphea (ca. 240 species), was mainly a Quaternary event. A phylogeny of the family is briefly explored and examples of specialized characters occurring in the oldest known genera are noted. The fossil record of the Lythraceae is presently too fragmentary to confidently reconstruct the early history of the family. The record indicates, however, that the family was well-diversified and widely dispersed globally over a wide latitudinal range by the end of the Paleocene.
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Cuphea fluviatilis (Lythraceae), a New Species from Antioquia, Colombia
Novon: A Journal for Botanical Nomenclature, 2009Co-Authors: Shirley A. GrahamAbstract:Cuphea fluviatilis S. A. Graham, a new species of the Lythraceae from the margins of the Rio Samana in Antioquia Department, Colombia, is described and illustrated. The taxonomic relationships of the species are unsettled. The species bears flowers closely similar to those of species in section Amazoniana (Lourteig) Lourteig, but lacks the distinctive malpighiaceous trichomes characterizing the section; its pollen morphology, a significant indicator of broad relationships in Cuphea, is also unlike that of the section. Pollen of section Amazoniana is typically nonsyncolpate, without protruding pores, and with a psilate to finely rugulate exine; that of C. fluviatilis is syncolpate with protruding pores and a striate exine, a type common to numerous species currently classified in the polyphyletic sections Brachyandra Koehne and Euandra Koehne.
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Biogeographic Patterns of Antillean Lythraceae
Systematic Botany, 2009Co-Authors: Shirley A. GrahamAbstract:Abstract The Lythraceae contribute eight genera and 41 species to the flora of the Antilles. Two genera, Ginoria and Haitia, and twenty-two species are endemic to the region. A summary of the distribution of each genus among the islands of the Greater Antilles is presented, together with an estimate of center of origin and mode and direction of introduction. Cuphea (15 species) and Ginoria (13 species) are best represented. Results of phylogenetic analyses for Rotala, Cuphea, and Ginoria aid in understanding the nearest relationships and geographic sources of the Antillean members of these genera. They suggest that Rotala was introduced twice from different directions and Cuphea was introduced from eastern South America a minimum of five to eight times into the Greater Antilles and at least three times into the Lesser Antilles. A paraphyletic Ginoria and Haitia, which is nested within the most derived species of Ginoria, are the result of adaptive radiation in situ in Cuba and Hispaniola from an undetermi...
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Phylogenetic Analysis of the Lythraceae Based on Four Gene Regions and Morphology
International Journal of Plant Sciences, 2005Co-Authors: Shirley A. Graham, Kenneth J. Sytsma, Jocelyn C. Hall, Su‐hua ShiAbstract:The family limits of the Lythraceae and relationships among the ca. 31 genera remain poorly known in spite of previous phylogenetic studies. We use morphology and DNA sequences from the rbcL gene, the trnL‐F region, and psaA‐ycf3 intergenic spacer of the chloroplast and the internal transcribed spacer region of the nucleus to explore relationships for up to 27 genera of the Lythraceae sensu stricto and the monogeneric families Duabangaceae, Punicaceae, Sonneratiaceae, and Trapaceae. Maximum parsimony, maximum likelihood, and Bayesian likelihood approaches are employed. Morphology alone provided little phylogenetic resolution. Results from individual gene regions were relatively well resolved and largely congruent, whereas basal relationships were poorly supported. A combined gene analysis of 20 genera produced one fully resolved maximum parsimony tree that corresponded closely to the maximum likelihood and Bayesian trees in which a monophyletic Lythraceae includes Duabanga, Punica, Sonneratia, and Trapa a...
Maryl Allen - One of the best experts on this subject based on the ideXlab platform.
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Cryptic self-incompatibility in tristylous Decodon verticillatus (Lythraceae).
American journal of botany, 1997Co-Authors: Christopher G. Eckert, Maryl AllenAbstract:There is growing evidence that many self-compatible plants control the level of self-fertilization with postpollination processes that give a siring advantage to cross pollen over self pollen through ‘‘cryptic self-incompatibility’’ (CSI). Previous marker-gene experiments with self-compatible, tristylous Decodon verticillatus (Lythraceae) have demonstrated a siring advantage to cross pollen, though the extent to which this advantage results from prezygotic discrimination vs. early acting inbreeding depression is not clear. Here, we provide evidence that prezygotic mechanisms are involved in this siring advantage by comparing pollen tube numbers at various times following cross- and self-pollination conducted in a natural population. In the 24 h following pollination, cross pollen yielded almost twice as many pollen tubes at various positions in the style compared to self pollen. After 36 and 48 h, the difference between pollen types had disappeared, suggesting that the advantage to cross pollen results from differences in the rate of pollen germination and/or tube growth rather than pollen tube attrition. Comparison of tube numbers after legitimate vs. illegitimate cross-pollination did not reveal any difference, suggesting that D. verticillatus possesses CSI unrelated to heteromorphic self- and intramorph-incompatibility found in other heterostylous members of the Lythraceae. CSI resulting from differential pollen tube growth may minimize geitonogamous selfing when cross pollen is abundant, while maximizing fecundity when cross pollen is scarce due to local clonal spread.
Katherine Mavraganis - One of the best experts on this subject based on the ideXlab platform.
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Evolutionary consequences of extensive morph loss in tristylous decodon verticillatus (Lythraceae): a shift from tristyly to distyly?
American Journal of Botany, 1996Co-Authors: Christopher G. Eckert, Katherine MavraganisAbstract:The evolution of distyly from tristyly has occurred repeatedly, especially in the Lythraceae. However, the evolutionary forces involved remain unclear since species exhibiting transitional stages between tristyly and distyly have rarely been studied. The self-compatible, wetland perennial Decodon verticillatus (Lythraceae) may provide this transitional variation since populations commonly lack style morphs, particularly the mid-styled (M) morph. In dimorphic populations lacking the M morph, anthers positioned at the mid level in both the long(L) and short-styled (S) morphs have lost their target stigma, setting the stage for either evolutionary repositioning of mid-level anthers to increase pollen export to L and S stigmas, or increased variability in mid-level anther position resulting from relaxed selection. We examined these two hypotheses by comparing floral morphology in eight dimorphic and ten trimorphic populations from throughout the species' range. We found no evidence that loss of the M morph has led to evolutionary modification of mid-level stamens. While mid-level stamens of the S morph were 11.0 ? 4.0% (mean ? 1 SE) longer than those of the L morph in dimorphic populations, divergence in stamen length between morphs occurred to the same extent (10.4 ? 2.0%) in trimorphic populations and cannot be attributed to the absence of the M morph. Analyses of variability using median ratio tests revealed no difference in the variability of mid-level stamen length between dimorphic and trimorphic populations. Mid-level stamens were not more variable than longand short-level stamens within dimorphic populations. The consistent divergence in midlevel stamens between the L and S morphs may reflect morph-specific differences in the optimal position of mid-level anthers for maximizing cross-pollination and avoiding self-fertilization.
