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Richard M K Saunders - One of the best experts on this subject based on the ideXlab platform.
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contrasting pollination ecology of disepalum species annonaceae evolutionary loss of the floral chamber and partial breakdown of Protogyny associated with a shift in pollination system
Botanical Journal of the Linnean Society, 2016Co-Authors: Chunchiu Pang, Richard M K SaundersAbstract:Disepalum comprises two monophyletic sister subgenera, Enicosanthellum and Disepalum, with strikingly different floral morphologies: the former has two whorls of unfused sepals, forming a partially enclosed floral chamber, whereas the latter possesses a single whorl of congenitally fused petals and lacks a floral chamber. The pollination ecologies of representative species are reported, including assessments of floral phenology, pollinators and floral thermogenesis. Disepalum pulchrum (subgenus Enicosanthellum) has hermaphroditic flowers with a pollination chamber and is protogynous with prolonged anthesis; it is pollinated by nitidulid beetles and drosophilid flies. Disepalum anomalum (subgenus Disepalum) is also hermaphroditic with prolonged anthesis, but has incomplete Protogyny due to overlapping pistillate and staminate phases; it is pollinated by meliponine bees, which are attracted by the pollen, but which are only able to transfer pollen to receptive stigmas during the overlap phase. Alternative evolutionary hypotheses are evaluated, including the possibility that the ancestor of the subgenus Disepalum lineage may have experienced a profound genetic mutation, possibly involving genes responsible for organ merism and fusion, resulting in the loss of the pollination chamber and hence favouring different floral visitors. The breakdown in Protogyny required for effective pollination is likely to have had significant ramifications on population genetic diversity.
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the evolution of alternative mechanisms that promote outcrossing in annonaceae a self compatible family of early divergent angiosperms
Botanical Journal of the Linnean Society, 2014Co-Authors: Chunchiu Pang, Richard M K SaundersAbstract:Annonaceae flowers are generally hermaphroditic and show high levels of outcrossing, but unlike many other early-divergent angiosperms lack a self-incompatibility mechanism. We reassess the diversity of mechanisms that have evolved to avoid self-pollination in the family. Protogyny occurs in all hermaphroditic flowers in the family, preventing autogamy but not geitonogamy. Herkogamy is rare in Annonaceae and is likely to be less effective as beetles move randomly around the flowers in search of food and/or mates. Geitonogamy is largely avoided in Annonaceae by combining Protogyny with floral synchrony, manifested as either pistillate/staminate-phase synchrony (in which pistillate-phase and staminate-phase flowers do not co-occur on an individual) or heterodichogamy (in which two phenologically distinct and reproductively isolated morphs coexist in populations). Unisexual flowers have evolved independently in several lineages, mostly as andromonoecy (possibly androdioecy). Functionally monoecious populations have evolved from andromonoecious ancestors through the loss of staminate function in structurally hermaphroditic flowers. This has been achieved in different ways, including incomplete pollen/stamen development and delayed anther dehiscence. Angiosperms display an enormous diversity of mechanisms to promote xenogamy, many of which are easily overlooked without fieldwork. Floral phenology is particularly important, especially cryptic differences in timing of organ maturation or abscission. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 93–109.
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the diversity and evolution of pollination systems in annonaceae
Botanical Journal of the Linnean Society, 2012Co-Authors: Richard M K SaundersAbstract:The pollination biology of Annonaceae has received considerable attention, with data now available for > 45% of the genera (or genus-equivalent clades) included in recent molecular phylogenetic analyses. This provides a basis for understanding evolutionary shifts in the pollination system within the family. The present study focuses on subfamilies Anaxagoreoideae, Ambavioideae and Annonoideae, for which robust, well-resolved phylogenetic trees are available. Information is summarized on the pollination biology of individual clades and the evolutionary adaptations favouring different pollinator guilds evaluated. Although the majority of species of Annonaceae are pollinated by small beetles, five other pollinator groups are known: large beetles, thrips, flies, bees and cockroaches. Small-beetle pollination is inferred as the ancestral pollination system, with all other systems being derived. Evolutionary shifts to pollination by large beetles, thrips and flies are unlikely to have been significantly constrained by previous adaptations favouring pollination by small beetles, as many of the adaptations to these different pollinator guilds are similar (including Protogyny, partially enclosed floral chambers and olfactory cues). In contrast, however, the evolutionary shift to bee pollination has presumably been constrained by both Protogyny (as pollen-collecting bees are unlikely to visit pistillate-phase flowers) and the presence of floral chambers. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 222–244.
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reproductive biology of two sympatric species of polyalthia annonaceae in sri lanka i pollination by curculionid beetles
International Journal of Plant Sciences, 2006Co-Authors: Rmcs Ratnayake, I A U N Gunatilleke, D S A Wijesundara, Richard M K SaundersAbstract:The pollination biology of two sympatric species, Polyalthia coffeoides and Polyalthia korinti (Annonaceae), is described in detail. An Endaeus species (Coleoptera: Curculionidae) is shown to be the major pollinator of both species, with Carpophilus plagiatipennis (Coleoptera: Nitidulidae) as the secondary pollinator of P. coffeoides. Both Polyalthia species show intrafloral dichogamy (Protogyny) with a reproductively inactive phase between the pistillate and staminate phases, although there is no evidence of interfloral dichogamy. A pollination chamber is formed by the inner petals throughout the reproductively active phases. Thermogenesis occurs in P. korinti, with internal floral temperatures up to 6°C above ambient levels. The heat is presumably an energy reward for the beetles. Although most pollination systems are regarded as diversified and opportunistic, specialized pollination systems are typical of the Annonaceae. Although P. coffeoides and P. korinti have overlapping distributions, habitats, an...
Spencer C H Barrett - One of the best experts on this subject based on the ideXlab platform.
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the consequences of monoecy and Protogyny for mating in wind pollinated carex
New Phytologist, 2009Co-Authors: Jannice Friedman, Spencer C H BarrettAbstract:Summary • Monoecy and Protogyny are widespread in wind-pollinated plants and have been interpreted as outcrossing mechanisms, though few studies have investigated their function. Carex, a large genus of anemophilous herbs, is predominantly monoecious and many species are protogynous. We investigated whether monoecy and Protogyny limit self-pollination in seven Carex species. • We conducted field experiments comparing stigmatic pollen loads and seed set between intact and emasculated stems. We tested for self-compatibility and evaluated pollen limitation of seed set by supplemental pollination. Finally, we measured outcrossing rates in open-pollinated and emasculated stems using allozyme markers. • Emasculated stems captured significantly less pollen than open-pollinated stems and set less seed. Pollen deposition during the female-only phase for intact stems was only 12% of the total captured. Outcrossing rates for three species indicated high selfing (range t = 0.03–0.39). Allozyme loci in the remaining species were monomorphic also suggesting high selfing. These results demonstrate that neither monoecy nor Protogyny is particularly effective at limiting self-fertilization. • Selection for the avoidance of selfing is unlikely to maintain monoecy in many Carex species although Protogyny may provide limited opportunities for outcrossing. We propose that geitonogamy in self-compatible wind-pollinated species with unisexual flowers may be widespread and provides reproductive assurance.
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The consequences of monoecy and Protogyny for mating in wind-pollinated Carex
2008Co-Authors: Spencer C H Barrett, Jannice FriedmanAbstract:• Monoecy and Protogyny are widespread in wind-pollinated plants and have been interpreted as outcrossing mechanisms, though few studies have investigated their function. Carex, a large genus of anemophilous herbs, is predominantly monoecious and many species are protogynous. We investigated whether monoecy and Protogyny limit self-pollination in seven Carex species. • We conducted field experiments comparing stigmatic pollen loads and seed set between intact and emasculated stems. We tested for self-compatibility and evaluated pollen limitation of seed set by supplemental pollination. Finally, we measured outcrossing rates in open-pollinated and emasculated stems using allozyme markers. • Emasculated stems captured significantly less pollen than open-pollinated stems and set less seed. Pollen deposition during the female-only phase for intact stems was only 12 % of the total captured. Outcrossing rates for three species indicated high selfing (range t = 0.03–0.39). Allozyme loci in the remaining species were monomorphic also suggesting high selfing. These results demon
Chunchiu Pang - One of the best experts on this subject based on the ideXlab platform.
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contrasting pollination ecology of disepalum species annonaceae evolutionary loss of the floral chamber and partial breakdown of Protogyny associated with a shift in pollination system
Botanical Journal of the Linnean Society, 2016Co-Authors: Chunchiu Pang, Richard M K SaundersAbstract:Disepalum comprises two monophyletic sister subgenera, Enicosanthellum and Disepalum, with strikingly different floral morphologies: the former has two whorls of unfused sepals, forming a partially enclosed floral chamber, whereas the latter possesses a single whorl of congenitally fused petals and lacks a floral chamber. The pollination ecologies of representative species are reported, including assessments of floral phenology, pollinators and floral thermogenesis. Disepalum pulchrum (subgenus Enicosanthellum) has hermaphroditic flowers with a pollination chamber and is protogynous with prolonged anthesis; it is pollinated by nitidulid beetles and drosophilid flies. Disepalum anomalum (subgenus Disepalum) is also hermaphroditic with prolonged anthesis, but has incomplete Protogyny due to overlapping pistillate and staminate phases; it is pollinated by meliponine bees, which are attracted by the pollen, but which are only able to transfer pollen to receptive stigmas during the overlap phase. Alternative evolutionary hypotheses are evaluated, including the possibility that the ancestor of the subgenus Disepalum lineage may have experienced a profound genetic mutation, possibly involving genes responsible for organ merism and fusion, resulting in the loss of the pollination chamber and hence favouring different floral visitors. The breakdown in Protogyny required for effective pollination is likely to have had significant ramifications on population genetic diversity.
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the evolution of alternative mechanisms that promote outcrossing in annonaceae a self compatible family of early divergent angiosperms
Botanical Journal of the Linnean Society, 2014Co-Authors: Chunchiu Pang, Richard M K SaundersAbstract:Annonaceae flowers are generally hermaphroditic and show high levels of outcrossing, but unlike many other early-divergent angiosperms lack a self-incompatibility mechanism. We reassess the diversity of mechanisms that have evolved to avoid self-pollination in the family. Protogyny occurs in all hermaphroditic flowers in the family, preventing autogamy but not geitonogamy. Herkogamy is rare in Annonaceae and is likely to be less effective as beetles move randomly around the flowers in search of food and/or mates. Geitonogamy is largely avoided in Annonaceae by combining Protogyny with floral synchrony, manifested as either pistillate/staminate-phase synchrony (in which pistillate-phase and staminate-phase flowers do not co-occur on an individual) or heterodichogamy (in which two phenologically distinct and reproductively isolated morphs coexist in populations). Unisexual flowers have evolved independently in several lineages, mostly as andromonoecy (possibly androdioecy). Functionally monoecious populations have evolved from andromonoecious ancestors through the loss of staminate function in structurally hermaphroditic flowers. This has been achieved in different ways, including incomplete pollen/stamen development and delayed anther dehiscence. Angiosperms display an enormous diversity of mechanisms to promote xenogamy, many of which are easily overlooked without fieldwork. Floral phenology is particularly important, especially cryptic differences in timing of organ maturation or abscission. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 93–109.
Jannice Friedman - One of the best experts on this subject based on the ideXlab platform.
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the consequences of monoecy and Protogyny for mating in wind pollinated carex
New Phytologist, 2009Co-Authors: Jannice Friedman, Spencer C H BarrettAbstract:Summary • Monoecy and Protogyny are widespread in wind-pollinated plants and have been interpreted as outcrossing mechanisms, though few studies have investigated their function. Carex, a large genus of anemophilous herbs, is predominantly monoecious and many species are protogynous. We investigated whether monoecy and Protogyny limit self-pollination in seven Carex species. • We conducted field experiments comparing stigmatic pollen loads and seed set between intact and emasculated stems. We tested for self-compatibility and evaluated pollen limitation of seed set by supplemental pollination. Finally, we measured outcrossing rates in open-pollinated and emasculated stems using allozyme markers. • Emasculated stems captured significantly less pollen than open-pollinated stems and set less seed. Pollen deposition during the female-only phase for intact stems was only 12% of the total captured. Outcrossing rates for three species indicated high selfing (range t = 0.03–0.39). Allozyme loci in the remaining species were monomorphic also suggesting high selfing. These results demonstrate that neither monoecy nor Protogyny is particularly effective at limiting self-fertilization. • Selection for the avoidance of selfing is unlikely to maintain monoecy in many Carex species although Protogyny may provide limited opportunities for outcrossing. We propose that geitonogamy in self-compatible wind-pollinated species with unisexual flowers may be widespread and provides reproductive assurance.
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The consequences of monoecy and Protogyny for mating in wind-pollinated Carex
2008Co-Authors: Spencer C H Barrett, Jannice FriedmanAbstract:• Monoecy and Protogyny are widespread in wind-pollinated plants and have been interpreted as outcrossing mechanisms, though few studies have investigated their function. Carex, a large genus of anemophilous herbs, is predominantly monoecious and many species are protogynous. We investigated whether monoecy and Protogyny limit self-pollination in seven Carex species. • We conducted field experiments comparing stigmatic pollen loads and seed set between intact and emasculated stems. We tested for self-compatibility and evaluated pollen limitation of seed set by supplemental pollination. Finally, we measured outcrossing rates in open-pollinated and emasculated stems using allozyme markers. • Emasculated stems captured significantly less pollen than open-pollinated stems and set less seed. Pollen deposition during the female-only phase for intact stems was only 12 % of the total captured. Outcrossing rates for three species indicated high selfing (range t = 0.03–0.39). Allozyme loci in the remaining species were monomorphic also suggesting high selfing. These results demon
Franz Holker - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE High Female Survival Promotes Evolution of Protogyny and Sexual Conflict
2016Co-Authors: Tobias Degen, Thomas Hovestadt, Oliver Mitesser, Franz HolkerAbstract:Existing models explaining the evolution of sexual dimorphism in the timing of emergence (SDT) in Lepidoptera assume equal mortality rates for males and females. The limiting as-sumption of equal mortality rates has the consequence that these models are only able to explain the evolution of emergence of males before females, i.e. protandry—the more com-mon temporal sequence of emergence in Lepidoptera. The models fail, however, in provid-ing adaptive explanations for the evolution of Protogyny, where females emerge before males, but Protogyny is not rare in insects. The assumption of equal mortality rates seems too restrictive for many insects, such as butterflies. To investigate the influence of unequal mortality rates on the evolution of SDT, we present a generalised version of a previously published model where we relax this assumption. We find that longer life-expectancy of fe-males compared to males can indeed favour the evolution of Protogyny as a fitness enhanc-ing strategy. Moreover, the encounter rate between females and males and the sex-ratio are two important factors that also influence the evolution of optimal SDT. If considered in-dependently for females and males the predicted strategies can be shown to be evolution
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high female survival promotes evolution of Protogyny and sexual conflict
PLOS ONE, 2015Co-Authors: Tobias Degen, Thomas Hovestadt, Oliver Mitesser, Franz HolkerAbstract:Existing models explaining the evolution of sexual dimorphism in the timing of emergence (SDT) in Lepidoptera assume equal mortality rates for males and females. The limiting assumption of equal mortality rates has the consequence that these models are only able to explain the evolution of emergence of males before females, i.e. protandry—the more common temporal sequence of emergence in Lepidoptera. The models fail, however, in providing adaptive explanations for the evolution of Protogyny, where females emerge before males, but Protogyny is not rare in insects. The assumption of equal mortality rates seems too restrictive for many insects, such as butterflies. To investigate the influence of unequal mortality rates on the evolution of SDT, we present a generalised version of a previously published model where we relax this assumption. We find that longer life-expectancy of females compared to males can indeed favour the evolution of Protogyny as a fitness enhancing strategy. Moreover, the encounter rate between females and males and the sex-ratio are two important factors that also influence the evolution of optimal SDT. If considered independently for females and males the predicted strategies can be shown to be evolutionarily stable (ESS). Under the assumption of equal mortality rates the difference between the females’ and males’ ESS remains typically very small. However, female and male ESS may be quite dissimilar if mortality rates are different. This creates the potential for an ‘evolutionary conflict’ between females and males. Bagworm moths (Lepidoptera: Psychidae) provide an exemplary case where life-history attributes are such that Protogyny should indeed be the optimal emergence strategy from the males’ and females’ perspectives: (i) Female longevity is considerably larger than that of males, (ii) encounter rates between females and males are presumably low, and (iii) females mate only once. Protogyny is indeed the general mating strategy found in the bagworm family.
