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Rodrigo B Singer - One of the best experts on this subject based on the ideXlab platform.
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The pollination biology of Sauroglossum elatum Lindl. (Orchidaceae: Spiranthinae): moth‐pollination and Protandry in neotropical Spiranthinae
Botanical Journal of the Linnean Society, 2020Co-Authors: Rodrigo B SingerAbstract:The pollination biology of Sauroglossum elatum Lindl (Orchidaceae: Spiranthinae) was studied in the State of Sao Paulo, south-eastern Brazil. This orchid is protandrous and almost fully self-compatible, but pollinator-dependent. Thus, pollinators are required for the plants to set fruits and seeds. The flowers are pollinated by moths of the family Noctuidae. Pollinia are dislodged when the moths probe flowers in the male phase. At this stage the stigmatic surface is inaccessible, so that the flowers can act only as pollen-donors. Flowers in the female phase present their stigmatic surfaces well exposed and dry viscidia; at this stage the flowers act as pollen receivers. Pollinarium-bearing moths, when visiting a flower in the female phase, will brush the pollinarium against the stigmatic surface, thus effecting the pollination. Moth-pollination is reported here for the first time for the orchid subtribe Spiranthinae. Protandry also occurs in a few additional Brazilian Spiranthinae. Based on the evidence presented in this work, Protandry in Spiranthinae is not necessarily linked to bumblebee pollination, as currently accepted. It is suggested that the occurrence of Protandry in Spiranthinae and in the closely related subtribes Prescottinae and Goodyerinae may also be a feature encompassing ecological and phylogenetic implications. Anecdotal ex-situ observations are briefly discussed. Cultivated specimens were actively visited by Tetragonisca angustula (Meliponini) bees. which broke the pollinaria, collected the pollen and eventually performed pollination by leaving small fragments of the pollinia on the stigmatic surface. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 138, 9–16.
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Morfología Floral Y Polinización De Orquídeas : El Segundo Libro De Charles Darwin
Acta Biológica Colombiana, 2009Co-Authors: Rodrigo B SingerAbstract:Darwin’s second book was totally dedicated to the floral functional morphology and pollination of temperate and tropical orchids. This book was published in 1862 and was likely conceived as an assemblage of evidence supporting ideas that were proposed in “On The Origin of The Species”; namely, the advantages of the intercrossing between different coespecific individuals, even if they are hermaphrodite (like the orchids). The great floral diversity and the outstanding number of reproductive strategies that promote cross-pollination in Orchidaceae fascinated Darwin who, in turn, used this plant group as a model to support his ideas. Darwin described for the first time and in a very accurate way, orchid reproductive strategies that clearly promote cross- pollination, such as Protandry in terrestrial orchids and the production of unisexual flowers in Catasetum, among many other important contributions. Darwin’s ideas and proposals regarding Orchidaceae are analyzed on the light of our present knowledge and prove to be mostly correct and valid
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the pollination biology of sauroglossum elatum lindl orchidaceae spiranthinae moth pollination and Protandry in neotropical spiranthinae
Botanical Journal of the Linnean Society, 2002Co-Authors: Rodrigo B SingerAbstract:The pollination biology of Sauroglossum elatum Lindl (Orchidaceae: Spiranthinae) was studied in the State of Sao Paulo, south-eastern Brazil. This orchid is protandrous and almost fully self-compatible, but pollinator-dependent. Thus, pollinators are required for the plants to set fruits and seeds. The flowers are pollinated by moths of the family Noctuidae. Pollinia are dislodged when the moths probe flowers in the male phase. At this stage the stigmatic surface is inaccessible, so that the flowers can act only as pollen-donors. Flowers in the female phase present their stigmatic surfaces well exposed and dry viscidia; at this stage the flowers act as pollen receivers. Pollinarium-bearing moths, when visiting a flower in the female phase, will brush the pollinarium against the stigmatic surface, thus effecting the pollination. Moth-pollination is reported here for the first time for the orchid subtribe Spiranthinae. Protandry also occurs in a few additional Brazilian Spiranthinae. Based on the evidence presented in this work, Protandry in Spiranthinae is not necessarily linked to bumblebee pollination, as currently accepted. It is suggested that the occurrence of Protandry in Spiranthinae and in the closely related subtribes Prescottinae and Goodyerinae may also be a feature encompassing ecological and phylogenetic implications. Anecdotal ex-situ observations are briefly discussed. Cultivated specimens were actively visited by Tetragonisca angustula (Meliponini) bees. which broke the pollinaria, collected the pollen and eventually performed pollination by leaving small fragments of the pollinia on the stigmatic surface. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 138, 9–16.
Yolanda E Morbey - One of the best experts on this subject based on the ideXlab platform.
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proximate causes of avian Protandry differ between subspecies with contrasting migration challenges
Behavioral Ecology, 2016Co-Authors: Heiko Schmaljohann, Yolanda E Morbey, Christoph M Meier, Debora Arlt, Franz Bairlein, Herman H Van Oosten, Susanne Akesson, Martin Buchmann, Nikita ChernetsovAbstract:In many migratory birds, males precede females during migration and arrival at the breeding sites. Three proximate mechanisms are proposed to explain this phenomenon of Protandry: males 1) winter closer to breeding sites, 2) start spring migration earlier, and/or 3) migrate faster than females. So far, the relative contribution of these mechanisms to Protandry is unknown. The present study investigated the importance of each of the 3 proximate mechanisms of Protandry for a songbird migrant wintering in Africa, the northern wheatear (Oenanthe oenanthe). Two subspecies co-occur in Europe on migration, of which the leucorhoa northern wheatears breeding from Iceland to Canada have to cross the North Atlantic, whereas the nominate form breeding in Europe does not face any significant sea barrier. We show that the leucorhoa subspecies had a significantly higher degree of Protandry at stopover sites across Europe than the oenanthe subspecies (−6 vs. −2 days). Leucorhoa northern wheatear’s higher degree of Protandry was associated with a larger age effect, in which old males preceded young males, and greater sex-specific differences in wing shape and refueling yielding higher migration speeds in males than females. In oenanthe northern wheatears, light-level geolocators revealed that males did not winter closer to the breeding sites or migrate faster than females, but initiated spring migration earlier. Our results demonstrate that the significance of the mechanisms causing Protandry can differ between related taxa and highlight the importance of the advancement in male arrival date with age as a potential factor shaping the degree of Protandry.
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Protandry sexual size dimorphism and adaptive growth
Journal of Theoretical Biology, 2013Co-Authors: Yolanda E MorbeyAbstract:Abstract Adaptive growth refers to the strategic adjustment of growth rate by individuals to maximize some component of fitness. The concept of adaptive growth proliferated in the 1990s, in part due to an influential theoretical paper by Peter Abrams and colleagues. In their 1996 paper, Abrams et al. explored the effects of time stress on optimal growth rate, development time, and adult size in seasonal organisms. In this review, I explore how the concept of adaptive growth informs our understanding of Protandry (the earlier arrival of males to sites of reproduction than females) and sexual size dimorphism in seasonal organisms. I conclude that growth rate variation is an important mechanism that helps to conserve optimal levels of Protandry and sexual size dimorphism in changing environments.
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stopover refueling rate underlies Protandry and seasonal variation in migration timing of songbirds
Behavioral Ecology, 2013Co-Authors: Christopher G Guglielmo, Chad L Seewagen, Yolanda E MorbeyAbstract:We used plasma metabolite analysis to assess refueling rates of songbirds at stopover sites in New York and test hypotheses that males refuel faster than females during spring (in 2 species), migrants refuel faster during spring than autumn (in 5 species), and adults refuel faster than juveniles during autumn (in 4 species). Model selection based on Akaike’s information criterion indicated that males had higher refueling rates than females during spring in both species tested. Spring migrants had higher refueling rates than autumn migrants in 4 of the 5 species we examined. Juvenile and adult refueling rates during autumn did not differ in any species. Our results indicate that variation in stopover refueling rate can operate as a mechanism for Protandry in spring and faster migration during spring than autumn. We found no evidence that juvenile refueling performance during autumn was poorer than that of adults.
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adaptive hypotheses for Protandry in arrival to breeding areas a review of models and empirical tests
Journal of Ornithology, 2012Co-Authors: Yolanda E Morbey, Timothy Coppack, Francisco PulidoAbstract:Our understanding of avian migration has progressed significantly, yet the selective conditions that favor the arrival of males before females at the site of reproduction remain largely unclear. Here, we review the leading adaptive hypotheses for Protandry, highlight some key empirical studies that test Protandry theory, and identify theoretical and empirical information demands. In general, Protandry should evolve in species where the variance in male reproductive success is larger than in females if the costs to males of earlier arrival relative to calendar date (viability selection) can be balanced by increased mating opportunities (sexual selection). Early arrival by males can provide ‘priority benefits’ that help in the monopolization of resources or ‘early bird draw benefits’ that increase opportunities for extra-pair mating. While some empirical studies are consistent with theoretical predictions regarding the important selection factors that influence Protandry (e.g., extrinsic mortality and extra-pair paternity), some are not, and some studies focus on ecological factors that have not been considered explicitly by theory. We call for an integrated theoretical approach to help formalize how Protandry should evolve in response to the antagonistic roles of natural and sexual selection, the nature of competitive asymmetries among males or females, sex-specific costs and benefits of early arrival, and various climate change scenarios.
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the interaction between reproductive lifespan and Protandry in seasonal breeders
Journal of Evolutionary Biology, 2004Co-Authors: Yolanda E Morbey, P A AbramsAbstract:The timing and duration of reproductive activities are highly variable both at the individual and population level. Understanding how this variation evolved by natural selection is fundamental to understanding many important aspects of an organism's life history, ecology and behaviour. Here, we combine game theoretic principles governing reproductive timing and the evolutionary theory of senescence to study the interaction between Protandry (the earlier arrival or emergence of males to breeding areas than females) and senescence in seasonal breeders. Our general model applies to males who are seeking to mate as frequently as possible over a relatively short period, and so is relevant to many organisms including annual insects and semelparous vertebrates. The model predicts that Protandry and maximum reproductive lifespans should increase in environments characterized by high survival and by a low competitive cost of maintaining the somatic machinery necessary for survival. In relatively short seasons under these same conditions, seasonal declines in the reproductive lifespans of males of equivalent quality will be evolutionarily stable. However, over a broad range of potential values for daily survival and maintenance cost, reproductive lifespan is expected to be relatively short and constant throughout a large fraction of the season. We applied the model to sockeye (or kokanee) salmon Oncorhynchus nerka and show that pronounced seasonal declines in reproductive lifespan, a distinctive feature of semelparous Oncorhynchus spp., is likely part of a male mating strategy to maximize mating opportunities.
Anders Pape Moller - One of the best experts on this subject based on the ideXlab platform.
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individual differences in Protandry sexual selection and fitness
Behavioral Ecology, 2009Co-Authors: Anders Pape Moller, Javier Balbontin, Jose Javier Cuervo, Ignacio G Hermosell, F De LopeAbstract:Protandry is the difference in arrival date between males and females, with competition among males for access to preferred territories (the rank advantage hypothesis) or mating success (the mate opportunity hypothesis) supposedly driving the evolution of Protandry. The fitness costs and benefits of Protandry accruing to individuals differing in degree of Protandry (arrival date of a male relative to the arrival date of his partner) have never been quantified. We analyzed the fitness consequences of sex differences in arrival date in the barn swallow Hirundo rustica, in which arrival date can be precisely estimated and the fitness of pairs differing in degree of individual Protandry assessed. Early arriving males had greater mating success than late arriving males. The number of extrapair offspring in own nests decreased with increasing degree of individual Protandry, whereas the number of offspring fathered by a focal male was unrelated to individual Protandry. There was directional selection on individual Protandry as shown by pairs with a larger than average degree of Protandry reproducing early and, hence, supposedly producing more recruits. There was also stabilizing selection on individual Protandry as shown by pairs with an intermediate degree of Protandry reproducing early. Annual production of fledglings increased with early arrival of males, but not with early arrival of females, once the effect of laying date had been considered, with no additional effect of individual Protandry. Neither male nor female survival was significantly related to degree of individual Protandry. These findings are consistent not only with the mate opportunity hypothesis but also with a sexual conflict hypothesis, suggesting that males and females differ in their optimal timing of arrival due to sex-specific fitness costs and benefits. Copyright 2009, Oxford University Press.
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tardy females impatient males Protandry and divergent selection on arrival date in the two sexes of the barn swallow
Behavioral Ecology and Sociobiology, 2007Co-Authors: Anders Pape MollerAbstract:Protandry reflects the earlier arrival of males than females to the site of reproduction. Such Protandry is hypothesised to arise from sex differences in costs and benefits of early arrival. I investigated temporal patterns of arrival date of male and female barn swallows Hirundo rustica and temporal patterns of selection to test the hypothesis that sex differences in selection account for sex differences in arrival date. Mean arrival date of male barn swallows but not of females advanced during the last 33 years, giving rise to an increasing sex difference in arrival date. Early arrival was favoured by increasingly better survival in males, while females showed an opposite pattern that did not reach significance, although the effect differed between sexes. Early arrival increased fecundity in both sexes equally.The sex difference in viability selection in relation to arrival date changed from positive to negative as the degree of Protandry increased in recent years, although there was no similar significant relationship for fecundity selection. Furthermore, sex differences in viability selection in a given year affected the degree of Protandry in the following year through differential survival of certain phenotypes over others. Finally, temporal changes in sex difference in viability selection and Protandry were related to an increase in the interval between first and second clutches, as the duration of the breeding season increased because of climatic amelioration. These findings suggest that arrival date is under divergent selection in the two sexes, providing a mechanism for the evolution of Protandry.
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Protandry sexual selection and climate change
Global Change Biology, 2004Co-Authors: Anders Pape MollerAbstract:Protandry refers to the earlier appearance of males before females at sites of reproduction. Sexual selection has been hypothesized to give rise to sex differences in benefits and costs of early arrival, thereby selecting for earlier appearance by the sex subject to more intense sexual selection. If sexual selection is more intense, there is a greater premium on early arrival among individuals of the chosen sex because of direct selection for earlier arrival. This hypothesis leads to the prediction that changes in the costs and benefits of early arrival related to changes in environmental conditions should particularly affect the sex that arrives first and hence the degree of Protandry. I tested this hypothesis using the Barn Swallow Hirundo rustica. During 1971‐2003, the degree of Protandry increased significantly in a Danish population because males advanced arrival date while females did not. This earlier arrival by males compared with females was correlated with a significant increase by over 1.2 standard deviations in the length of the outermost tail feathers of males, a secondary sexual character, suggesting direct selection on both Protandry and the secondary sexual character. Environmental conditions during spring migration in Northern Africa, as reflected by the normalized difference vegetation index, have deteriorated since 1984, resulting in increased mortality among males during spring migration, but not among females, and this deterioration of climatic conditions was positively correlated with an increasing degree of Protandry. Likewise, an increase in April temperatures at the breeding grounds during recent decades is positively correlated with increased Protandry, apparently because males can arrive earlier without increasing the fitness cost of early arrival. Local population size did not predict changes in arrival date. These findings suggest that rapid changes in climate can cause a change in degree of Protandry and secondary sexual characters.
William E Bradshaw - One of the best experts on this subject based on the ideXlab platform.
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Protandry the relationship between emergence time and male fitness in the pitcher plant mosquito
Ecology, 2002Co-Authors: Christina M Holzapfel, William E BradshawAbstract:Protandry is the emergence or arrival into a seasonal population of males before females and is widespread among both plants and animals. Conceptually, Protandry should be subject to stabilizing selection because early emerging males risk death before mating and late-emerging males miss opportunities to mate. However, for any given male, the optimal emergence time may depend upon the mean and distribution of emergence of other males in the population. Using lifetime offspring sired as our criterion of reproductive success, we found that, in laboratory populations of the pitcher-plant mosquito, Wyeomyia smithii, there is, indeed, stabilizing selection acting on the optimal time for male emergence, and that the specific optimum does depend upon emergence time of other males in the population. In addition, male cohorts achieved greater reproductive success when their emergence was spread over several days rather than occurring in a single day. However, reproductive success did not differ between normal and superdispersed emergence distri- butions, suggesting that, under more variable, natural conditions, the specific pattern of male emergence may be far less important than variation in emergence time, per se.
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heritability of development time and Protandry in the pitcher plant mosquito wyeomyia smithii
Ecology, 1997Co-Authors: William E Bradshaw, Cheryl A Kleckner, Christina M Holzapfel, Jeffrey J HardAbstract:Models of Protandry (1) assume implicitly or explicitly that independent evolution of male and female preadult development times is possible and (2) assume or assert that Protandry should increase in populations that are univoltine or at least composed of discrete, nonoverlapping generations. Herein we examine these assumptions in the pitcher-plant mosquito, Wyeomyia smithii. Heritability and additive genetic variance of development time are higher in female than in male W. smithii. Protandry is higher in lines selected for slow development than in lines selected for fast development or in unselected control lines. Protandry is therefore capable of evolving. Contrary to predictions based on sexual selection, southern populations with multiple, overlapping generations are just as protandrous as northern bi- and univoltine populations with discrete generations. Voltinism and developmental synchrony of the population do not appear to have been major selective factors in the evolution of Protandry in W. smithii. We propose that Protandry can be maintained by natural selection in multivoltine populations with overlapping generations as a consequence of sexually dimorphic fitness criteria. Selection should minimize development time in males but maximize growth rate in females. In W. smithii, females achieve higher growth rate than males but also harbor greater genetic variation for development time, indicating that selection has, indeed, minimized development time to a greater extent in males than in females. We conclude that if both natural and sexual selection are involved in the maintenance of Protandry in populations of W. smithii, then their relative importance changes with the degree of generation overlap.
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Protandry in aedes sierrensis the significance of temporal variation in female fecundity
Ecology, 1995Co-Authors: Cheryl A Kleckner, William A Hawley, William E Bradshaw, Christina M Holzapfel, Ian J FisherAbstract:Protandry, the early emergence of males into a seasonally breeding pop- ulation, has been described mathematically as a mating strategy resulting from sexual selection on both sexes. A key implicit assumption in Protandry models is that all matings contribute equally to a male's reproductive success. We build a simulation model of pro- tandry based on field censuses and investigate the consequences of size-specific temporal variation in female fecundity for the optimal timing of Protandry in the western treehole mosquito, Aedes sierrensis. We show that theoretical predictions of Protandry are robust when differential female fecundity is incorporated into a model of Protandry in A. sierrensis. In addition, we utilize field data and laboratory experiments to elucidate the selective forces acting on both sexes of this mosquito. Under conditions of reduced per capita resources, males minimized development time by pupating at lower mass; females maximized mass by delaying pupation. These gender-specific, homeostatic adjustments to food and density, which result in density-dependent Protandry, indicate that Protandry is the result of selection on independent fitness criteria in each sex.
Christina M Holzapfel - One of the best experts on this subject based on the ideXlab platform.
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Protandry the relationship between emergence time and male fitness in the pitcher plant mosquito
Ecology, 2002Co-Authors: Christina M Holzapfel, William E BradshawAbstract:Protandry is the emergence or arrival into a seasonal population of males before females and is widespread among both plants and animals. Conceptually, Protandry should be subject to stabilizing selection because early emerging males risk death before mating and late-emerging males miss opportunities to mate. However, for any given male, the optimal emergence time may depend upon the mean and distribution of emergence of other males in the population. Using lifetime offspring sired as our criterion of reproductive success, we found that, in laboratory populations of the pitcher-plant mosquito, Wyeomyia smithii, there is, indeed, stabilizing selection acting on the optimal time for male emergence, and that the specific optimum does depend upon emergence time of other males in the population. In addition, male cohorts achieved greater reproductive success when their emergence was spread over several days rather than occurring in a single day. However, reproductive success did not differ between normal and superdispersed emergence distri- butions, suggesting that, under more variable, natural conditions, the specific pattern of male emergence may be far less important than variation in emergence time, per se.
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heritability of development time and Protandry in the pitcher plant mosquito wyeomyia smithii
Ecology, 1997Co-Authors: William E Bradshaw, Cheryl A Kleckner, Christina M Holzapfel, Jeffrey J HardAbstract:Models of Protandry (1) assume implicitly or explicitly that independent evolution of male and female preadult development times is possible and (2) assume or assert that Protandry should increase in populations that are univoltine or at least composed of discrete, nonoverlapping generations. Herein we examine these assumptions in the pitcher-plant mosquito, Wyeomyia smithii. Heritability and additive genetic variance of development time are higher in female than in male W. smithii. Protandry is higher in lines selected for slow development than in lines selected for fast development or in unselected control lines. Protandry is therefore capable of evolving. Contrary to predictions based on sexual selection, southern populations with multiple, overlapping generations are just as protandrous as northern bi- and univoltine populations with discrete generations. Voltinism and developmental synchrony of the population do not appear to have been major selective factors in the evolution of Protandry in W. smithii. We propose that Protandry can be maintained by natural selection in multivoltine populations with overlapping generations as a consequence of sexually dimorphic fitness criteria. Selection should minimize development time in males but maximize growth rate in females. In W. smithii, females achieve higher growth rate than males but also harbor greater genetic variation for development time, indicating that selection has, indeed, minimized development time to a greater extent in males than in females. We conclude that if both natural and sexual selection are involved in the maintenance of Protandry in populations of W. smithii, then their relative importance changes with the degree of generation overlap.
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Protandry in aedes sierrensis the significance of temporal variation in female fecundity
Ecology, 1995Co-Authors: Cheryl A Kleckner, William A Hawley, William E Bradshaw, Christina M Holzapfel, Ian J FisherAbstract:Protandry, the early emergence of males into a seasonally breeding pop- ulation, has been described mathematically as a mating strategy resulting from sexual selection on both sexes. A key implicit assumption in Protandry models is that all matings contribute equally to a male's reproductive success. We build a simulation model of pro- tandry based on field censuses and investigate the consequences of size-specific temporal variation in female fecundity for the optimal timing of Protandry in the western treehole mosquito, Aedes sierrensis. We show that theoretical predictions of Protandry are robust when differential female fecundity is incorporated into a model of Protandry in A. sierrensis. In addition, we utilize field data and laboratory experiments to elucidate the selective forces acting on both sexes of this mosquito. Under conditions of reduced per capita resources, males minimized development time by pupating at lower mass; females maximized mass by delaying pupation. These gender-specific, homeostatic adjustments to food and density, which result in density-dependent Protandry, indicate that Protandry is the result of selection on independent fitness criteria in each sex.
