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David M. Althoff - One of the best experts on this subject based on the ideXlab platform.
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specialization in the Yucca Yucca moth obligate pollination mutualism a role for antagonism
American Journal of Botany, 2016Co-Authors: David M. AlthoffAbstract:PREMISE OF THE STUDY: Specialized brood pollination systems involve both mutualism and antagonism in the overall interaction and have led to diversification in both plants and insects. Although largely known for mutualism, the role of the antagonistic side of the interaction in these systems has been overlooked. Specialization may be driven by plant defenses to feeding by the insect larvae that consume and kill developing plant ovules. The interaction among Yuccas and Yucca moths is cited as a classic example of the importance of mutualism in specialization and diversification. Pollinators moths are very host specific, but whether this specificity is due to adult pollination ability or larval feeding ability is unclear. Here, I test the potential role of antagonism in driving specialization among Yuccas and Yucca moths. METHODS: I examined the ability of the most-polyphagous Yucca moth pollinator, Tegeticula Yuccasella, to pollinate and develop on five Yucca species used across its range. Yucca species endemic to the Great Plains and Texas were transplanted to a common garden in Syracuse, New York and exposed to the local pollinator moth population over 3 years. KEY RESULTS: Local moths visited all but one of the Yucca species, but had drastically lower rates of successful larval development on non-natal Yucca species in comparison to the local host species. CONCLUSION: Specialization in many brood pollination systems may be strongly influenced by the antagonistic rather than the mutualistic side of the overall interaction, suggesting that antagonistic coevolution is a possible source of diversification.
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Specialization in the Yucca–Yucca moth obligate pollination mutualism: A role for antagonism?
American journal of botany, 2016Co-Authors: David M. AlthoffAbstract:Premise of the study Specialized brood pollination systems involve both mutualism and antagonism in the overall interaction and have led to diversification in both plants and insects. Although largely known for mutualism, the role of the antagonistic side of the interaction in these systems has been overlooked. Specialization may be driven by plant defenses to feeding by the insect larvae that consume and kill developing plant ovules. The interaction among Yuccas and Yucca moths is cited as a classic example of the importance of mutualism in specialization and diversification. Pollinators moths are very host specific, but whether this specificity is due to adult pollination ability or larval feeding ability is unclear. Here, I test the potential role of antagonism in driving specialization among Yuccas and Yucca moths. Methods I examined the ability of the most-polyphagous Yucca moth pollinator, Tegeticula Yuccasella, to pollinate and develop on five Yucca species used across its range. Yucca species endemic to the Great Plains and Texas were transplanted to a common garden in Syracuse, New York and exposed to the local pollinator moth population over 3 years. Key results Local moths visited all but one of the Yucca species, but had drastically lower rates of successful larval development on non-natal Yucca species in comparison to the local host species. Conclusion Specialization in many brood pollination systems may be strongly influenced by the antagonistic rather than the mutualistic side of the overall interaction, suggesting that antagonistic coevolution is a possible source of diversification.
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The role of abiotic and biotic factors in determining coexistence of multiple pollinators in the Yucca-Yucca moth mutualism.
Ecography, 2016Co-Authors: Clive T. Darwell, Kari A. Segraves, David M. AlthoffAbstract:The determinants of a species' geographic distribution are a combination of both abiotic and biotic factors. Environmental niche modeling of climatic factors has been instrumental in documenting the role of abiotic factors in a species' niche. Integrating this approach with data from species interactions provides a means to assess the relative roles of abiotic and biotic components. Here, we examine whether the high host specificity typically exhibited in the active pollination mutualism between Yuccas and Yucca moths is the result of differences in climatic niche requirements that limit Yucca moth distributions or the result of competition among mutualistic moths that would co-occur on the same Yucca species. We compared the species distribution models of two Tegeticula pollinator moths that use the geographically widespread plant Yucca filamentosa. Tegeticula Yuccasella occurs throughout eastern North America whereas T. cassandra is restricted to the southeastern portion of the range, primarily occurring in Florida. Species distribution models demonstrate that T. cassandra is restricted climatically to the southeastern United States and T. Yuccasella is predicted to be able to live across all of eastern North America. Data on moth abundances in Florida demonstrate that both moth species are present on Y. filamentosa; however, T. cassandra is numerically dominant. Taken together, the results suggest that moth geographic distributions are heavily influenced by climate, but competition among pollinating congeners will act to restrict populations of moth species that co-occur.
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Florivore impacts on plant reproductive success and pollinator mortality in an obligate pollination mutualism
Oecologia, 2013Co-Authors: David M. Althoff, Wei Xiao, Sarah Sumoski, Kari A. SegravesAbstract:Florivores are present in many pollination systems and can have direct and indirect effects on both plants and pollinators. Although the impact of florivores are commonly examined in facultative pollination mutualisms, their effects on obligate mutualism remain relatively unstudied. Here, we used experimental manipulations and surveys of naturally occurring plants to assess the effect of florivory on the obligate pollination mutualism between Yuccas and Yucca moths. Yucca filamentosa (Agavaceae) is pollinated by the moth Tegeticula cassandra (Lepidoptera: Prodoxidae), and the mutualism also attracts two florivores: a generalist, the leaf-footed bug Leptoglossus phyllopus (Hemiptera: Coreidae), and a specialist, the beetle Hymenorus densus (Coleoptera: Tenebrionidae). Experimental manipulations of leaf-footed bug densities on side branches of Y. filamentosa inflorescences demonstrated that feeding causes floral abscission but does not reduce pollen or seed production in the remaining flowers. Similar to the leaf-footed bugs, experimental manipulations of beetle densities within individual flowers demonstrated that beetle feeding also causes floral abscission, but, in addition, the beetles also cause a significant reduction in pollen availability. Path analyses of phenotypic selection based on surveys of naturally occurring plants revealed temporal variation in the plant traits important to plant fitness and the effects of the florivores on fitness. Leaf-footed bugs negatively impacted fitness when fewer plants were flowering and leaf-footed bug density was high, whereas beetles had a positive effect on fitness when there were many plants flowering and their densities were low. This positive effect was likely due to adult beetles consuming Yucca moth eggs while having a negligible effect on floral abscission. Together, the actions of both florivores either augmented the relationship of plant traits and fitness or slightly weakened the relationship. Overall, the results suggest that, although florivores are always present during flowering, the impact of florivores on phenotypic selection in Yuccas is strongly mitigated by changes in their densities on plants from year to year. In contrast, both florivores consistently influenced pollinator larval mortality through floral abscission, and H. densus beetles additionally via the consumption of pollinator eggs.
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Geographic isolation trumps coevolution as a driver of Yucca and Yucca moth diversification.
Molecular phylogenetics and evolution, 2011Co-Authors: David M. Althoff, Kari A. Segraves, Christopher Irwin Smith, Jim Leebens-mack, Olle PellmyrAbstract:Coevolution is thought to be especially important in diversification of obligate mutualistic interactions such as the one between Yuccas and pollinating Yucca moths. We took a three-step approach to examine if plant and pollinator speciation events were likely driven by coevolution. First, we tested whether there has been co-speciation between Yuccas and pollinator Yucca moths in the genus Tegeticula (Prodoxidae). Second, we tested whether co-speciation also occurred between Yuccas and commensalistic Yucca moths in the genus Prodoxus (Prodoxidae) in which reciprocal evolutionary change is unlikely. Finally, we examined the current range distributions of Yuccas in relationship to pollinator speciation events to determine if plant and moth speciation events likely occurred in sympatry or allopatry. Co-speciation analyses of Yuccas with their coexisting Tegeticula pollinator and commensalistic Prodoxus lineages demonstrated phylogenetic congruence between both groups of moths and Yuccas, even though moth lineages differ in the type of interaction with Yuccas. Furthermore, Yucca species within a lineage occur primarily in allopatry rather than sympatry. We conclude that biogeographic factors are the overriding force in plant and pollinator moth speciation and significant phylogenetic congruence between the moth and plant lineages is likely due to shared biogeography rather than coevolution.
Olle Pellmyr - One of the best experts on this subject based on the ideXlab platform.
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Geographic isolation trumps coevolution as a driver of Yucca and Yucca moth diversification.
Molecular phylogenetics and evolution, 2011Co-Authors: David M. Althoff, Kari A. Segraves, Christopher Irwin Smith, Jim Leebens-mack, Olle PellmyrAbstract:Coevolution is thought to be especially important in diversification of obligate mutualistic interactions such as the one between Yuccas and pollinating Yucca moths. We took a three-step approach to examine if plant and pollinator speciation events were likely driven by coevolution. First, we tested whether there has been co-speciation between Yuccas and pollinator Yucca moths in the genus Tegeticula (Prodoxidae). Second, we tested whether co-speciation also occurred between Yuccas and commensalistic Yucca moths in the genus Prodoxus (Prodoxidae) in which reciprocal evolutionary change is unlikely. Finally, we examined the current range distributions of Yuccas in relationship to pollinator speciation events to determine if plant and moth speciation events likely occurred in sympatry or allopatry. Co-speciation analyses of Yuccas with their coexisting Tegeticula pollinator and commensalistic Prodoxus lineages demonstrated phylogenetic congruence between both groups of moths and Yuccas, even though moth lineages differ in the type of interaction with Yuccas. Furthermore, Yucca species within a lineage occur primarily in allopatry rather than sympatry. We conclude that biogeographic factors are the overriding force in plant and pollinator moth speciation and significant phylogenetic congruence between the moth and plant lineages is likely due to shared biogeography rather than coevolution.
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pattern and timing of diversification in Yucca agavaceae specialized pollination does not escalate rates of diversification
Proceedings of The Royal Society B: Biological Sciences, 2008Co-Authors: Christopher Irwin Smith, Olle Pellmyr, David M. Althoff, Jim Leebensmack, Manuel Balcazarlara, Kari A. SegravesAbstract:The Yucca–Yucca moth interaction is one of the most well-known and remarkable obligate pollination mutualisms, and is an important study system for understanding coevolution. Previous research suggests that specialist pollinators can promote rapid diversification in plants, and theoretical work has predicted that obligate pollination mutualism promotes cospeciation between plants and their pollinators, resulting in contemporaneous, parallel diversification. However, a lack of information about the age of Yucca has impeded efforts to test these hypotheses. We used analyses of 4322 AFLP markers and cpDNA sequence data representing six non-protein-coding regions (trnT–trnL, trnL, trnL intron, trnL–trnF, rps16 and clpP intron 2) from all 34 species to recover a consensus organismal phylogeny, and used penalized likelihood to estimate divergence times and speciation rates in Yucca. The results indicate that the pollination mutualism did not accelerate diversification, as Yucca diversity (34 species) is not significantly greater than that of its non-moth-pollinated sister group, Agave sensu latissimus (240 species). The new phylogenetic estimates also corroborate the suggestion that the plant–moth pollination mutualism has at least two origins within the Agavaceae. Finally, age estimates show significant discord between the age of Yucca (ca 6–10 Myr) and the current best estimates for the age of their pollinators (32–40 Myr).
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Strong conservation of floral scent composition in two allopatric Yuccas
Journal of chemical ecology, 2006Co-Authors: Glenn P. Svensson, Olle Pellmyr, Robert A. RagusoAbstract:Floral scent has been suggested to play a key role in the obligate pollination mutualism between Yuccas and Yucca moths. We analyzed floral fragrance compounds of Yucca elata with headspace collection followed by gas chromatography and mass spectrometry, and compared the odor blend with the recently characterized blend of the allopatric Yucca filamentosa. A principal component analysis based on 20 scent compounds revealed that the floral odor bouquets of Y. elata and Y. filamentosa are virtually identical. Although the two plants belong to the same section of capsular-fruited Yuccas, they rely on different species of Tegeticula moths for pollination and probably have been allopatric for several million years. Yet, their floral odor blends are very similar, which may indicate that strong selection by obligate pollinators counteracts drift or divergence in this trait.
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Replicated host-race formation in bogus Yucca moths: genetic and ecological divergence of Prodoxus quinquepunctellus on Yucca hosts
Evolutionary Ecology Research, 2005Co-Authors: Glenn P. Svensson, David M. Althoff, Olle PellmyrAbstract:Goal: Assess host-race formation in certain moths by examining their genetic and ecological differentiation. Organisms: Stalk-feeding moths, Prodoxus quinquepunctellus, collected from sympatric populations of Yucca elata and Y. rostrata in west Texas, USA. Results: Moths on the two Yuccas differed significantly in mtDNA haplotype frequencies, emergence time, wing dot number, body size, and ovipositor size and shape. Conclusion: Host-race formation has probably occurred in this Yucca moth although genetic divergence was low.
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Defection by plants in the Yucca-Yucca moth association: a test of the cheater plant hypothesis for Yucca treculeana
Oikos, 2004Co-Authors: Beau A. Crabb, Olle PellmyrAbstract:In mutualisms, an underlying conflict of interests may select for defection from providing benefits. In the obligate mutualism between Yuccas and Yucca moths, where pollination service and seeds for pollinator larvae are traded, it has been suggested that some individuals in a population of Y. baccata may defect by preventing pollinator egg or larvae from development. We tested this hypothesis in Y. treculeana, another species suggested to contain cheater plants. Five specific predictions were tested during two years of study. A prediction that a surplus of plants without pollinator larvae should be present was met. Predicted existence of two distinct fruit morphs was rejected, and none of several highly variable morphological traits were linked to presence/absence of larvae. Predicted excess of intact seeds in the fruits of plants without larvae was not found; in fact, such plants produced fewer seeds, contrary to the hypothesis. A suggestion that inverse frequency-dependent fitness could explain the pattern was rejected. Contrary to prediction, distribution of larvae of a closely related cheater Yucca moth was positively associated with pollinator larvae, even though it would not be affected by the proposed killing mechanism. The results together provide strong support against the existence of cheater plants in Y. treculeana.
John F. Addicott - One of the best experts on this subject based on the ideXlab platform.
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Direct and indirect effects of ants on seed predation in moth/Yucca mutualisms
Écoscience, 2008Co-Authors: Rebecca S. Snell, John F. AddicottAbstract:Abstract Strong indirect effects are important in community and ecosystem processes, particularly in aquatic communities where predation and competition are the dominant processes. In this study, we examine an obligate pollination/seed predation mutualism between moths and Yuccas and the balance of direct and indirect effects of ants, aphids, and cheater moths on this mutualism. Cheater moths (Tegeticula corruptrix) do not pollinate Yuccas but oviposit into developing fruit, where their larvae consume Yucca seeds. The overall effect of ants and aphids on Yuccas was positive. Ants and aphids had no negative impact on the number of fruit retained per plant, and they had a positive effect on the average number of viable seeds per fruit. Yuccas with high ant and aphid densities had a 60% increase in viable, uneaten seeds. This increase in seed production was largely due to the negative interactions between ants and T. corruptrix. The reduction of cheater ovipositions saved Yuccas almost 46 seeds per fruit, pl...
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Regulation of the mutualism between Yuccas and Yucca moths: intrinsic and extrinsic factors affecting flower retention
Oikos, 2000Co-Authors: Shelley A. Humphries, John F. AddicottAbstract:Yuccas initiate far more flowers than they can mature as fruit, thereby providing opportunities for them to mature flowers of the highest quality. Flower quality in Yuccas has both intrinsic and extrinsic components. Intrinsic components relate to flower morphology and inflorescence architecture. Yucca moths (Tegeticula spp., Incurvariidae), the sole pollinators and primary seed predators of most Yuccas (Yucca spp., Agavaceae), mediate extrinsic components of flower quality through their ovipositions in flowers, and the quantity and quality of pollen that they transfer. In addition, intrinsic and extrinsic components interact as a function of flowering phenology and moth activity within inflorescences. We investigated selective abscission of flowers in Y. kanabensis with respect to various combinations of intrinsic and extrinsic factors. First, we considered the effect of high and low pollen loads delivered to different subsets of flowers and in different presentation orders. In the absence of moth ovipositions, Y. kanabensis is sensitive to the amount of pollen that moths deliver and tends to retain high pollen flowers, even when all flowers receive sufficient pollen for full fertilization. However, pollen delivery sequence and the position of flowers with an inflorescence modify this high pollen effect. We then considered the interplay between high and low pollen combined with moth ovipositions and found that the number of ovipositions dominated the pollen effect. Finally, we considered number of ovipositions in conjunction with different flowers in the blooming sequence while controlling pollen levels and found that the clear effect of ovipositions on flower fate can be tempered by where the flower is in the blooming sequence. These results have implications for the regulation of the mutualism between Yuccas and Yucca moths, indicating that Yuccas are capable of regulating costs, retaining flowers of relative high quality and selectively abscising the rest. Yucca sensitivity to several intrinsic and extrinsic factors allows the plant to respond flexibly to the pollination environment and several species of moths.
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Limiting the costs of mutalism: multiple modes of interaction between Yuccas and Yucca moths.
Proceedings of the Royal Society of London. Series B: Biological Sciences, 1999Co-Authors: John F. Addicott, Tan BaoAbstract:In pollination–seed predation mutualisms between Yuccas and Yucca moths, conflicts of interest exist for Yuccas, because benefits of increased pollination may be outweighed by increased seed consumption. These conflicts raise the problem of what limits seed consumption, and ultimately what limits or regulates moth populations. Although the current hypothesis is that Yuccas should selectively abscise flowers with high numbers of Yucca–moth eggs, within–inflorescence selective abscission occurs in only one of the three moth–Yucca systems that we studied. It occurs only when oviposition directly damages developing ovules, and does not, therefore, provide a general explanation for the resolution of moth–Yucca conflicts. Within–locule egg mortality provides an alternative and stronger mechanism for limiting seed damage, and generating density–dependent mortality for Yucca–moth populations. However, the most important feature of moth–Yucca systems is that they are diverse, encompassing multiple modes of interaction, each with different consequences for limiting and regulating Yucca moths.
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Regulation of mutualism between Yuccas and Yucca moths : population level processes
Oikos, 1998Co-Authors: John F. AddicottAbstract:This study addresses five population level processes associated with regulation of the pollination/seed predation mutualism between Yucca kanabensis and two species of pollinating Yucca moths, one each from the deep and shallow groups of species within the Tegeticula Yuccasella species complex. 1) The adult Yucca moth population is apparently relatively constant from year to year, as shown by the inverse relationship between the proportion of rosettes flowering and the proportion of flowers receiving oviposition/pollination visits from Yucca moths. 2) The relative success of Yucca moths as measured by the proportion of visited flowers retained as fruit, is an inverse function of the ratio of moths to flowers, as measured by visitation. 3) The interactions between Yucca moths and Yuccas is different for deeps and shallows. Not only was there differential retention of flowers visited by shallows relative to flowers visited by deeps, but the differential appears to be frequency dependent. 4) Within seasons, fruiting and therefore the success of Yucca moths may be concentrated into a period of just a few days. This non-random pattern of fruiting differed from both the pattern of flowering and the pattern of visitation, and was a function of higher than average retention of visited flowers. However, no set of factors correlated consistently with these population level windows of fruit retention. 5) The interaction between Yucca moths and Yuccas shifts with the density of Yucca moths: the number of eggs laid per flower increases with visitation, and the amount of pollen carried by Yucca moths decreases with moth density. I discuss these results in the context of hypotheses for the regulation of the Yucca/Yucca moth mutualism, and hypotheses for how these population patterns should affect the life histories and behavior of Yucca moths.
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Regulation of mutualism between Yuccas and Yucca moths : is oviposition behavior responsive to selective abscission of flowers ?
Oikos, 1998Co-Authors: Reid D. Wilson, John F. AddicottAbstract:In the obligate pollination/seed predation mutualism between Yuccas and Yucca moths, Yuccas may exert considerable control over the interaction by abscising a high proportion of visited flowers. Because egg mortality in abscised flowers is 100%, Yucca moths should avoid ovipositing in, or decrease the number of eggs laid in flowers more likely to abscise. The focus of out study was to demonstrate experimentally (1) the extent to which abscission is non-random with respect to the number and kinds Yucca moth ovipositions, and (2) the extent to which Yucca moths modify their oviposition behavior in response to the probable fate of a flower as determined by the number and kinds of previous ovipositions in a flower. To address these problems we studied the interaction between Yucca kanabensis and its two species of pollinating Yucca moths, one each from the deep and shallow groups in the Tegeticula Yuccasella species complex. We demonstrate that the presence of deep ovipositions increased abscission rates of flowers with shallow ovipositions, the presence of shallow ovipositions had no effect on abscission of flowers with deep ovipositions, and the probability of abscission increased with the number of deep ovipositions but was independent of the number of shallow ovipositions. These results indicate that regulation of mutualism through selective abscission of fruit works for deeps but not for shallows. We predicted that Yucca moths should avoid flowers with deep ovipositions and seek out flowers with shallow ovipositions. We found, however, that shallows showed only a weak avoidance of flowers with deep ovipositions, and that deeps did not avoid ovipositing in flowers that already contained deep eggs. We consider three hypotheses that could explain the weak fit between out predictions and observations.
Kari A. Segraves - One of the best experts on this subject based on the ideXlab platform.
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The role of abiotic and biotic factors in determining coexistence of multiple pollinators in the Yucca-Yucca moth mutualism.
Ecography, 2016Co-Authors: Clive T. Darwell, Kari A. Segraves, David M. AlthoffAbstract:The determinants of a species' geographic distribution are a combination of both abiotic and biotic factors. Environmental niche modeling of climatic factors has been instrumental in documenting the role of abiotic factors in a species' niche. Integrating this approach with data from species interactions provides a means to assess the relative roles of abiotic and biotic components. Here, we examine whether the high host specificity typically exhibited in the active pollination mutualism between Yuccas and Yucca moths is the result of differences in climatic niche requirements that limit Yucca moth distributions or the result of competition among mutualistic moths that would co-occur on the same Yucca species. We compared the species distribution models of two Tegeticula pollinator moths that use the geographically widespread plant Yucca filamentosa. Tegeticula Yuccasella occurs throughout eastern North America whereas T. cassandra is restricted to the southeastern portion of the range, primarily occurring in Florida. Species distribution models demonstrate that T. cassandra is restricted climatically to the southeastern United States and T. Yuccasella is predicted to be able to live across all of eastern North America. Data on moth abundances in Florida demonstrate that both moth species are present on Y. filamentosa; however, T. cassandra is numerically dominant. Taken together, the results suggest that moth geographic distributions are heavily influenced by climate, but competition among pollinating congeners will act to restrict populations of moth species that co-occur.
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Florivore impacts on plant reproductive success and pollinator mortality in an obligate pollination mutualism
Oecologia, 2013Co-Authors: David M. Althoff, Wei Xiao, Sarah Sumoski, Kari A. SegravesAbstract:Florivores are present in many pollination systems and can have direct and indirect effects on both plants and pollinators. Although the impact of florivores are commonly examined in facultative pollination mutualisms, their effects on obligate mutualism remain relatively unstudied. Here, we used experimental manipulations and surveys of naturally occurring plants to assess the effect of florivory on the obligate pollination mutualism between Yuccas and Yucca moths. Yucca filamentosa (Agavaceae) is pollinated by the moth Tegeticula cassandra (Lepidoptera: Prodoxidae), and the mutualism also attracts two florivores: a generalist, the leaf-footed bug Leptoglossus phyllopus (Hemiptera: Coreidae), and a specialist, the beetle Hymenorus densus (Coleoptera: Tenebrionidae). Experimental manipulations of leaf-footed bug densities on side branches of Y. filamentosa inflorescences demonstrated that feeding causes floral abscission but does not reduce pollen or seed production in the remaining flowers. Similar to the leaf-footed bugs, experimental manipulations of beetle densities within individual flowers demonstrated that beetle feeding also causes floral abscission, but, in addition, the beetles also cause a significant reduction in pollen availability. Path analyses of phenotypic selection based on surveys of naturally occurring plants revealed temporal variation in the plant traits important to plant fitness and the effects of the florivores on fitness. Leaf-footed bugs negatively impacted fitness when fewer plants were flowering and leaf-footed bug density was high, whereas beetles had a positive effect on fitness when there were many plants flowering and their densities were low. This positive effect was likely due to adult beetles consuming Yucca moth eggs while having a negligible effect on floral abscission. Together, the actions of both florivores either augmented the relationship of plant traits and fitness or slightly weakened the relationship. Overall, the results suggest that, although florivores are always present during flowering, the impact of florivores on phenotypic selection in Yuccas is strongly mitigated by changes in their densities on plants from year to year. In contrast, both florivores consistently influenced pollinator larval mortality through floral abscission, and H. densus beetles additionally via the consumption of pollinator eggs.
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Geographic isolation trumps coevolution as a driver of Yucca and Yucca moth diversification.
Molecular phylogenetics and evolution, 2011Co-Authors: David M. Althoff, Kari A. Segraves, Christopher Irwin Smith, Jim Leebens-mack, Olle PellmyrAbstract:Coevolution is thought to be especially important in diversification of obligate mutualistic interactions such as the one between Yuccas and pollinating Yucca moths. We took a three-step approach to examine if plant and pollinator speciation events were likely driven by coevolution. First, we tested whether there has been co-speciation between Yuccas and pollinator Yucca moths in the genus Tegeticula (Prodoxidae). Second, we tested whether co-speciation also occurred between Yuccas and commensalistic Yucca moths in the genus Prodoxus (Prodoxidae) in which reciprocal evolutionary change is unlikely. Finally, we examined the current range distributions of Yuccas in relationship to pollinator speciation events to determine if plant and moth speciation events likely occurred in sympatry or allopatry. Co-speciation analyses of Yuccas with their coexisting Tegeticula pollinator and commensalistic Prodoxus lineages demonstrated phylogenetic congruence between both groups of moths and Yuccas, even though moth lineages differ in the type of interaction with Yuccas. Furthermore, Yucca species within a lineage occur primarily in allopatry rather than sympatry. We conclude that biogeographic factors are the overriding force in plant and pollinator moth speciation and significant phylogenetic congruence between the moth and plant lineages is likely due to shared biogeography rather than coevolution.
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pattern and timing of diversification in Yucca agavaceae specialized pollination does not escalate rates of diversification
Proceedings of The Royal Society B: Biological Sciences, 2008Co-Authors: Christopher Irwin Smith, Olle Pellmyr, David M. Althoff, Jim Leebensmack, Manuel Balcazarlara, Kari A. SegravesAbstract:The Yucca–Yucca moth interaction is one of the most well-known and remarkable obligate pollination mutualisms, and is an important study system for understanding coevolution. Previous research suggests that specialist pollinators can promote rapid diversification in plants, and theoretical work has predicted that obligate pollination mutualism promotes cospeciation between plants and their pollinators, resulting in contemporaneous, parallel diversification. However, a lack of information about the age of Yucca has impeded efforts to test these hypotheses. We used analyses of 4322 AFLP markers and cpDNA sequence data representing six non-protein-coding regions (trnT–trnL, trnL, trnL intron, trnL–trnF, rps16 and clpP intron 2) from all 34 species to recover a consensus organismal phylogeny, and used penalized likelihood to estimate divergence times and speciation rates in Yucca. The results indicate that the pollination mutualism did not accelerate diversification, as Yucca diversity (34 species) is not significantly greater than that of its non-moth-pollinated sister group, Agave sensu latissimus (240 species). The new phylogenetic estimates also corroborate the suggestion that the plant–moth pollination mutualism has at least two origins within the Agavaceae. Finally, age estimates show significant discord between the age of Yucca (ca 6–10 Myr) and the current best estimates for the age of their pollinators (32–40 Myr).
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FLORIVORES LIMIT COST OF MUTUALISM IN THE Yucca–Yucca MOTH ASSOCIATION
Ecology, 2008Co-Authors: Kari A. SegravesAbstract:Multispecies interactions may have important consequences for the ecology and evolution of mutualism by changing the cost-to-benefit ratio. Here I determine whether florivorous beetles can limit moth populations and influence the costs of the mutualism between Yuccas and their pollinating moths. Yucca moths actively pollinate Yucca flowers, and their larvae feed on a portion of the seeds. I used a manipulative field experiment to examine the hypothesis that the characteristic feeding behavior of the florivorous beetle Hymenorus densus may increase mortality of pollinator moth eggs and reduce the costs incurred by the plant. The results indicated that H. densus consumes moth eggs and that the consumption rate matches levels of moth mortality typically observed in these populations. On average, beetles consumed 1-2 eggs per flower, which translates into an increase in seed production of ∼16-32% per fruit. Counterintuitively, these results suggest that florivores can limit moth populations and reduce the costs incurred by the plant.
Tao Wang - One of the best experts on this subject based on the ideXlab platform.
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separation and bioactive assay of 25r s spirostanol saponin diastereomers from Yucca schidigera roezl mojave stems
Molecules, 2018Co-Authors: Lu Qu, Song Wu, Haiyang Yu, Peijian Huang, Jingya Ruan, Tao WangAbstract:In order to find a simple, generic, efficient separation method for 25R/S-spirostanol saponin diastereomers, the liquid chromatographic retention behaviors of C12 carbonylation and C12 unsubstituted 25R/S-spirostanol saponin diastereomers on different stationary phases (C8, C18, C30 columns) and different mobile phases (MeOH-1% CH3COOH and CH3CN-1% CH3COOH) were investigated. A C30 column was firstly found to offer the highest efficiency for the separation of this kind of diastereomers than C8 and C18 columns. Meanwhile, the analysis results indicated that both CH3CN-1% CH3COOH and MeOH-1% CH3COOH eluate systems were selective for C12 unsubstituted 25R/S-spirostanol saponin diastereomers, while MeOH-1% CH3COOH possessed better selectivity for C12 carbonylation ones. Using the abovementioned analysis method, six pairs of 25R/S-spirostanol saponin diastereomers 1a–6a and 1b–6b from Yucca schidigera Roezl (Mojave) were isolated successfully by using HPLC on C30 column for the first time. Among them, three pairs were new ones, named as (25R)-Yucca spirostanoside E1 (1a), (25S)-Yucca spirostanoside E1 (1b), (25R)-Yucca spirostanoside E2 (2a), (25S)-Yucca spirostanoside E2 (2b), (25R)-Yucca spirostanoside E3 (3a), (25S)-Yucca spirostanoside E3 (3b), respectively. Moreover, 3a, 5a, 6a, 3b–6b showed strong inhibitory activities on the growth of SW620 cell lines with the IC50 values of 12.02–69.17 μM.
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Separation and Bioactive Assay of 25R/S-Spirostanol Saponin Diastereomers from Yucca schidigera Roezl (Mojave) Stems
Molecules, 2018Co-Authors: Lu Qu, Song Wu, Haiyang Yu, Peijian Huang, Jingya Ruan, Tao WangAbstract:In order to find a simple, generic, efficient separation method for 25R/S-spirostanol saponin diastereomers, the liquid chromatographic retention behaviors of C12 carbonylation and C12 unsubstituted 25R/S-spirostanol saponin diastereomers on different stationary phases (C8, C18, C30 columns) and different mobile phases (MeOH-1% CH3COOH and CH3CN-1% CH3COOH) were investigated. A C30 column was firstly found to offer the highest efficiency for the separation of this kind of diastereomers than C8 and C18 columns. Meanwhile, the analysis results indicated that both CH3CN-1% CH3COOH and MeOH-1% CH3COOH eluate systems were selective for C12 unsubstituted 25R/S-spirostanol saponin diastereomers, while MeOH-1% CH3COOH possessed better selectivity for C12 carbonylation ones. Using the abovementioned analysis method, six pairs of 25R/S-spirostanol saponin diastereomers 1a–6a and 1b–6b from Yucca schidigera Roezl (Mojave) were isolated successfully by using HPLC on C30 column for the first time. Among them, three pairs were new ones, named as (25R)-Yucca spirostanoside E1 (1a), (25S)-Yucca spirostanoside E1 (1b), (25R)-Yucca spirostanoside E2 (2a), (25S)-Yucca spirostanoside E2 (2b), (25R)-Yucca spirostanoside E3 (3a), (25S)-Yucca spirostanoside E3 (3b), respectively. Moreover, 3a, 5a, 6a, 3b–6b showed strong inhibitory activities on the growth of SW620 cell lines with the IC50 values of 12.02–69.17 μM.