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Joan E. Strassmann - One of the best experts on this subject based on the ideXlab platform.
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Social amoebae mating types do not invest unequally in sexual offspring
Journal of Evolutionary Biology, 2017Co-Authors: Tracy E. Douglas, David C. Queller, Joan E. StrassmannAbstract:Unequal investment by different sexes in their progeny is common and includes differential investment in the zygote and differential care of the young. The social amoeba Dictyostelium discoideum has a sexual stage in which isogamous cells of any two of the three mating types fuse to form a zygote which then attracts hundreds of other cells to the Macrocyst. The latter cells are cannibalized and so make no genetic contribution to reproduction. Previous literature suggests that this sacrifice may be induced in cells of one mating type by cells of another, resulting in a higher than expected production of Macrocysts when the inducing type is rare and giving a reproductive advantage to this social cheat. We tested this hypothesis in eight trios of field-collected clones of each of the three D. discoideum mating types by measuring Macrocyst production at different pairwise frequencies. We found evidence that supported differential contribution in only two of the 24 clone pairs, so this pattern is rare and clone-specific. In general, we did not reject the hypothesis that the mating types contribute cells relative to their proportion in the population. We also found a significant quadratic relationship between partner frequency and Macrocyst production, suggesting that when one clone is rare, Macrocyst production is limited by partner availability. We were also unable to replicate previous findings that Macrocyst production could be induced in the absence of a compatible mating partner. Overall, mating type-specific differential investment during sex is unlikely in microbial eukaryotes like D. discoideum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species ( Dictyostelium purpureum ). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum . Results We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance. Conclusions D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum . Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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phylogeography and sexual Macrocyst formation in the social amoeba dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: David C. Queller, N. J. Mehdiabadi, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:BACKGROUND: Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.\n\nRESULTS: We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance.\n\nCONCLUSIONS: D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum. Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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Phylogeny, reproductive isolation and kin recognition in the social amoeba Dictyostelium purpureum
Evolution, 2009Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Little is known about the population structure of social microorganisms, yet such studies are particularly interesting for the ways that genetic variation impacts their social evolution. Dictyostelium, a eukaryotic microbe widely used as a developmental model, has a social fruiting stage in which some formerly independent individuals die to help others. To assess genetic variation within the social amoeba Dictyostelium purpureum, we sequenced approximately 4000 base pairs of ribosomal DNA (rDNA) from 37 isolates collected in Texas, Virginia, and Japan. Our analysis showed extensive genetic variation between populations and clear evidence of phylogenetic structure. We identified three major phylogenetic groups that were more different than other accepted species pairs. Tests using pairs of clones showed that both sexual Macrocyst and asexual fruiting body formation were influenced by genetic divergence. Macrocysts were less likely to form between pairs of clones from different groups than from the same group. There was also a correlation between the genetic divergence of a pair of clones and their degree of mixing within fruiting bodies. These observations suggest that cryptic species might occur within D. purpureum and, more importantly, reveal how genetic variation impacts social interactions.
N. J. Mehdiabadi - One of the best experts on this subject based on the ideXlab platform.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species ( Dictyostelium purpureum ). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum . Results We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance. Conclusions D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum . Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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phylogeography and sexual Macrocyst formation in the social amoeba dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: David C. Queller, N. J. Mehdiabadi, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:BACKGROUND: Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.\n\nRESULTS: We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance.\n\nCONCLUSIONS: D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum. Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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Phylogeny, reproductive isolation and kin recognition in the social amoeba Dictyostelium purpureum
Evolution, 2009Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Little is known about the population structure of social microorganisms, yet such studies are particularly interesting for the ways that genetic variation impacts their social evolution. Dictyostelium, a eukaryotic microbe widely used as a developmental model, has a social fruiting stage in which some formerly independent individuals die to help others. To assess genetic variation within the social amoeba Dictyostelium purpureum, we sequenced approximately 4000 base pairs of ribosomal DNA (rDNA) from 37 isolates collected in Texas, Virginia, and Japan. Our analysis showed extensive genetic variation between populations and clear evidence of phylogenetic structure. We identified three major phylogenetic groups that were more different than other accepted species pairs. Tests using pairs of clones showed that both sexual Macrocyst and asexual fruiting body formation were influenced by genetic divergence. Macrocysts were less likely to form between pairs of clones from different groups than from the same group. There was also a correlation between the genetic divergence of a pair of clones and their degree of mixing within fruiting bodies. These observations suggest that cryptic species might occur within D. purpureum and, more importantly, reveal how genetic variation impacts social interactions.
Marcus R. Kronforst - One of the best experts on this subject based on the ideXlab platform.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species ( Dictyostelium purpureum ). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum . Results We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance. Conclusions D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum . Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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phylogeography and sexual Macrocyst formation in the social amoeba dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: David C. Queller, N. J. Mehdiabadi, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:BACKGROUND: Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.\n\nRESULTS: We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance.\n\nCONCLUSIONS: D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum. Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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Phylogeny, reproductive isolation and kin recognition in the social amoeba Dictyostelium purpureum
Evolution, 2009Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Little is known about the population structure of social microorganisms, yet such studies are particularly interesting for the ways that genetic variation impacts their social evolution. Dictyostelium, a eukaryotic microbe widely used as a developmental model, has a social fruiting stage in which some formerly independent individuals die to help others. To assess genetic variation within the social amoeba Dictyostelium purpureum, we sequenced approximately 4000 base pairs of ribosomal DNA (rDNA) from 37 isolates collected in Texas, Virginia, and Japan. Our analysis showed extensive genetic variation between populations and clear evidence of phylogenetic structure. We identified three major phylogenetic groups that were more different than other accepted species pairs. Tests using pairs of clones showed that both sexual Macrocyst and asexual fruiting body formation were influenced by genetic divergence. Macrocysts were less likely to form between pairs of clones from different groups than from the same group. There was also a correlation between the genetic divergence of a pair of clones and their degree of mixing within fruiting bodies. These observations suggest that cryptic species might occur within D. purpureum and, more importantly, reveal how genetic variation impacts social interactions.
David C. Queller - One of the best experts on this subject based on the ideXlab platform.
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Social amoebae mating types do not invest unequally in sexual offspring
Journal of Evolutionary Biology, 2017Co-Authors: Tracy E. Douglas, David C. Queller, Joan E. StrassmannAbstract:Unequal investment by different sexes in their progeny is common and includes differential investment in the zygote and differential care of the young. The social amoeba Dictyostelium discoideum has a sexual stage in which isogamous cells of any two of the three mating types fuse to form a zygote which then attracts hundreds of other cells to the Macrocyst. The latter cells are cannibalized and so make no genetic contribution to reproduction. Previous literature suggests that this sacrifice may be induced in cells of one mating type by cells of another, resulting in a higher than expected production of Macrocysts when the inducing type is rare and giving a reproductive advantage to this social cheat. We tested this hypothesis in eight trios of field-collected clones of each of the three D. discoideum mating types by measuring Macrocyst production at different pairwise frequencies. We found evidence that supported differential contribution in only two of the 24 clone pairs, so this pattern is rare and clone-specific. In general, we did not reject the hypothesis that the mating types contribute cells relative to their proportion in the population. We also found a significant quadratic relationship between partner frequency and Macrocyst production, suggesting that when one clone is rare, Macrocyst production is limited by partner availability. We were also unable to replicate previous findings that Macrocyst production could be induced in the absence of a compatible mating partner. Overall, mating type-specific differential investment during sex is unlikely in microbial eukaryotes like D. discoideum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species ( Dictyostelium purpureum ). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum . Results We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance. Conclusions D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum . Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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phylogeography and sexual Macrocyst formation in the social amoeba dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: David C. Queller, N. J. Mehdiabadi, Marcus R. Kronforst, Joan E. StrassmannAbstract:Background Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.
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Phylogeography and sexual Macrocyst formation in the social amoeba Dictyostelium giganteum
BMC Evolutionary Biology, 2010Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:BACKGROUND: Microorganisms are ubiquitous, yet we are only beginning to understand their diversity and population structure. Social amoebae (Dictyostelia) are a diverse group of unicellular eukaryotic microbes that display a unique social behaviour upon starvation in which cells congregate and then some die to help others survive and disperse. The genetic relationships among co-occurring cells have a major influence on the evolution of social traits and recent population genetic analysis found extensive genetic variation and possible cryptic speciation in one dictyostelid species (Dictyostelium purpureum). To further characterize the interplay among genetic variation, species boundaries, social behaviour, and reproductive isolation in the Dictyostelia, we conducted phylogenetic analyses and mating experiments with the geographically widespread social amoeba Dictyostelium giganteum.\n\nRESULTS: We sequenced approximately 4,000 basepairs of the nuclear ribosomal DNA from 24 isolates collected from Texas, Michigan, Massachusetts, Virginia, and Wisconsin and identified 16 unique haplotypes. Analyses of the sequence data revealed very little genetic differentiation among isolates and no clear evidence of phylogenetic structure, although there was evidence for some genetic differentiation between the Massachusetts and Texas populations. These results suggest that sexual mating (Macrocyst formation) is not likely to correlate with either genetic or geographical distance. To test this prediction, we performed 108 mating experiments and found no association between mating probability and genetic or geographical distance.\n\nCONCLUSIONS: D. giganteum isolates from across North America display little genetic variation, phylogeographic structure, and genetic differentiation among populations relative to the cryptic species observed within D. purpureum. Furthermore, variation that does exist does not predict the probability of mating among clones. These results have important implications for our understanding of speciation and social evolution in microbes.
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Phylogeny, reproductive isolation and kin recognition in the social amoeba Dictyostelium purpureum
Evolution, 2009Co-Authors: N. J. Mehdiabadi, David C. Queller, Marcus R. Kronforst, Joan E. StrassmannAbstract:Little is known about the population structure of social microorganisms, yet such studies are particularly interesting for the ways that genetic variation impacts their social evolution. Dictyostelium, a eukaryotic microbe widely used as a developmental model, has a social fruiting stage in which some formerly independent individuals die to help others. To assess genetic variation within the social amoeba Dictyostelium purpureum, we sequenced approximately 4000 base pairs of ribosomal DNA (rDNA) from 37 isolates collected in Texas, Virginia, and Japan. Our analysis showed extensive genetic variation between populations and clear evidence of phylogenetic structure. We identified three major phylogenetic groups that were more different than other accepted species pairs. Tests using pairs of clones showed that both sexual Macrocyst and asexual fruiting body formation were influenced by genetic divergence. Macrocysts were less likely to form between pairs of clones from different groups than from the same group. There was also a correlation between the genetic divergence of a pair of clones and their degree of mixing within fruiting bodies. These observations suggest that cryptic species might occur within D. purpureum and, more importantly, reveal how genetic variation impacts social interactions.
Y. Maeda - One of the best experts on this subject based on the ideXlab platform.
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The ethylene action in the development of cellular slime molds: an analogy to higher plants
Protoplasma, 1992Co-Authors: A. Amagai, Y. MaedaAbstract:The cellular slime mold Dictyostelium mucoroides -7 (Dm 7) and its mutant (MF 1) exhibit sexual or asexual development depending upon culture conditions. During the sexual cycle Macrocyst formation occurs, whereas sorocarps containing spores and stalk cells are asexually formed. As previously reported, the Macrocyst formation is marked by the emergence of true zygotes, and is induced by a potent plant hormone, ethylene. The concentration of ethylene required for Macrocyst induction was determined to establish the similarity of ethylene action between this organism and higher plants. Macrocysts are induced by low (1 μl/l) exogenous concentrations of ethylene. Higher concentrations (10–1,000 ul/l) also gave essentially the same inductive activity. Ethionine, an analogue of methionine, was found to inhibit zygote formation during sexual development through its interference with ethylene production by Dm 7 and MF 1 cells. In fact, the inhibitory effect of ethionine was mostly nullified by the application of ethylene, S-adenosyl-L-methionine, or 1-aminocyclopropane-1-carboxylic acid. Taken together these results suggest that both the effective concentration of ethylene and the pathway of ethylene biosynthesis in D. mucoroides may be similar to those in higher plants. Ethylene was also found to be produced in various species and strains of cellular slime molds, even during the asexual process. The possible functions of ethylene in the asexual development are discussed in relation to cell aggregation and differentiation.
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Involvement of cytoplasmic pH in the production of ethylene, a potent inducer of sexual development inDictyostelium mucoroides
Protoplasma, 1991Co-Authors: N. Iijima, A. Amagai, Y. MaedaAbstract:Dictyostelium mucoroides-7 (Dm 7) and a mutant MF 1 derived from it exhibit two developmental pathways: sorocarp formation occurs during the asexual process, and Macrocyst formation during the sexual cycle. The two developmental pathways are mainly regulated by two chemical substances: 3′,5′-cyclic adenosine monophosphate (cAMP) and ethylene. Recently, we have demonstrated that cytoplasmic pH (pH_i) has a critical role for the choice of developmental pathways, higher pH_i being favourable to Macrocyst formation. Thereupon, attention was riveted to the relation of pH_i to biosynthesis of cAMP and ethylene. Effect of pH_i on the production and release of ethylene, a potent inducer of Macrocyst formation, was examined, using the two facing culture method. The result showed that lowered pH_i inhibits ethylene production, thus resulting in a failure of cells to form Macrocysts. The accumulation of cAMP, an inhibitor of Macrocyst formation, was found to vary depending on extracellular pH (pH_o), but diethylstilbestrol (DES) that is a proton pump inhibitor and also an inhibitor of Macrocyst formation had no significant effect on the accumulation. Taken together these results indicate that higher pH_i may induce Macrocyst formation through enhancement of ethylene production rather than inhibition of cAMP synthesis.
