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John H Willis - One of the best experts on this subject based on the ideXlab platform.
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patterns of Hybrid Seed inviability in the mimulus guttatus sp complex reveal a potential role of parental conflict in reproductive isolation
Current Biology, 2020Co-Authors: Maya Wilson Brown, Jenn M Coughlan, John H WillisAbstract:Summary Genomic conflicts may play a central role in the evolution of reproductive barriers. Theory predicts that early-onset Hybrid inviability may stem from conflict between parents for resource allocation to offspring. Here, we describe M. decorus: a group of cryptic species within the M. guttatus species complex that are largely reproductively isolated by Hybrid Seed inviability (HSI). HSI between M. guttatus and M. decorus is common and strong, but populations of M. decorus vary in the magnitude and directionality of HSI with M. guttatus. Patterns of HSI between M. guttatus and M. decorus, as well as within M. decorus, conform to the predictions of parental conflict: first, reciprocal F1s exhibit size differences and parent-of-origin-specific endosperm defects; second, the extent of asymmetry between reciprocal F1 Seed size is correlated with asymmetry in HSI; and third, inferred differences in the extent of conflict predict the extent of HSI between populations. We also find that HSI is rapidly evolving, as populations that exhibit the most HSI are each others’ closest relative. Lastly, although all populations appear largely outcrossing, we find that the differences in the inferred strength of conflict scale positively with π, suggesting that demographic or life history factors other than transitions to self-fertilization may influence the rate of parental-conflict-driven evolution. Overall, these patterns suggest the rapid evolution of parent-of-origin-specific resource allocation alleles coincident with HSI within and between M. guttatus and M. decorus. Parental conflict may therefore be an important evolutionary driver of reproductive isolation.
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patterns of Hybrid Seed inviability in perennials of the mimulus guttatus sp complex reveal a potential role of parental conflict in reproductive isolation
bioRxiv, 2018Co-Authors: Jenn M Coughlan, Maya Wilson Brown, John H WillisAbstract:Hybrid inviability is a common reproductive barrier in nature, yet the evolutionary drivers of post-zygotic reproductive isolation are relatively unknown. One hypothesis is that of parental conflict, wherein differential optima for resource allocation between mothers and fathers leads to rapid evolution of maternal and paternal resource allocation alleles. Inviable Hybrids are then the manifestation of mismatched maternal and paternal alleles, which result in inappropriate Hybrid growth and ultimately death. Here we describe a group of relatively cryptic species nested within the M. guttatus species complex which show tremendous reproductive isolation through Hybrid Seed inviability (HSI). We explore the role of parental conflict in HSI between M. guttatus and a morphological variant, M. decorus. We find that M. decorus is genetically distinct from M. guttatus, despite exceptional phenotypic overlap. Reciprocal crosses between M. guttatus and M. decorus from across their ranges indicate that HSI is both common and strong, but that populations of M. decorus vary in their ability to cross with M. guttatus. Variation in HSI can be attributed in part to variation in ploidy among populations of M. decorus, but we also find two distinct clades of diploid M. decorus which exhibit oppositely asymmetric HSI with M. guttatus. Using only diploids, we show that HSI is associated with asymmetries in reciprocal Hybrid Seed size, suggesting a role of parent-of-origin effects on growth in HSI. Despite being each others closest relative, crosses between these two clades of M. decorus show complete reproductive isolation via HSI with accompanying parent-of-origin effects on growth. Overall, these patterns suggest the rapid evolution of parent-of-origin specific resource allocation alleles coincident with HSI between M. guttatus and M. decorus, as well as HSI between populations of M. decorus. Parental conflict may therefore be an important evolutionary driver of reproductive isolation in this system.
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disruption of endosperm development is a major cause of Hybrid Seed inviability between mimulus guttatus and mimulus nudatus
New Phytologist, 2016Co-Authors: Elen Oneal, John H Willis, Robert G. FranksAbstract:Divergence of developmental mechanisms within populations could lead to Hybrid developmental failure, and might be a factor driving speciation in angiosperms. We investigate patterns of endosperm and embryo development in Mimulus guttatus and the closely related, serpentine endemic Mimulus nudatus, and compare them to those of reciprocal Hybrid Seed. We address whether disruption in Hybrid Seed development is the primary source of reproductive isolation between these sympatric taxa. M. guttatus and M. nudatus differ in the pattern and timing of endosperm and embryo development. Some Hybrid Seeds exhibit early disruption of endosperm development and are completely inviable, while others develop relatively normally at first, but later exhibit impaired endosperm proliferation and low germination success. These developmental patterns are reflected in mature Hybrid Seeds, which are either small and flat (indicating little to no endosperm) or shriveled (indicating reduced endosperm volume). Hybrid Seed inviability forms a potent reproductive barrier between M. guttatus and M. nudatus. We shed light on the extent of developmental variation between closely related species within the M. guttatus species complex, an important ecological model system, and provide a partial mechanism for the Hybrid barrier between M. guttatus and M. nudatus.
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disruption of endosperm development is a major cause of Hybrid Seed inviability between mimulus guttatus and m nudatus
bioRxiv, 2015Co-Authors: Elen Oneal, John H Willis, Robert G. FranksAbstract:Divergence of developmental mechanisms within populations may lead to Hybrid developmental failure and inviability, and may be a factor driving speciation in flowering plants. We investigate the patterns of early and late embryo and endosperm development of Seed from Mimulus guttatus and the closely related, serpentine endemic M. nudatus, and compare those patterns to that of Hybrid Seed derived from reciprocal, interspecific crosses. We address whether disruption in Hybrid Seed development is the primary source of reproductive isolation between these sympatric taxa. M. guttatus and M. nudatus differ in the pattern and timing of endosperm and embryo development. Some Hybrid Seed exhibit early disruption of endosperm development and are completely inviable, while other Hybrid Seed exhibit comparatively normal early development, but show impaired endosperm proliferation. These developmental patterns underlie the phenotypes of mature Seed, which are either very small and flat, (indicating little to no endosperm), or shriveled, (indicating reduced endosperm volume). Both phenotypes have low germination success. Hybrid Seed inviability forms a potent reproductive barrier between M. guttatus and M. nudatus. We provide a partial developmental mechanism for the Hybrid barrier between M. guttatus and M. nudatus. In addition to illustrating the early stages of endosperm and embryo development, we shed light on the extent of developmental variation between closely related species within this important ecological model system.
Ce Harwood - One of the best experts on this subject based on the ideXlab platform.
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patterns of Hybrid Seed production in adjacent Seed orchards of acacia auriculiformis and a mangium in vietnam
Annals of Forest Science, 2019Co-Authors: Ce Harwood, Chi Q Nghiem, Rod A Griffin, Re VaillancourtAbstract:Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of Hybridisation events were found within 60 m from the boundary. Understanding pollen dispersal has important implications for breeding and Seed production of pure species and Hybrid Acacia. We examined patterns of Hybrid production in adjacent clonal Seed orchards of A. auriculiformis and A. mangium in Vietnam. We assessed the frequency of Hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of Hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and Hybrid material. Hybrid frequency differed significantly among individual clones (P < 0.001) but not between species (A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no Hybrids. The level of interspecific Hybridisation declined significantly (P < 0.001) with increasing distance, and no Hybrid Seed was produced by trees located more than 116 m from the inter-orchard boundary. Pooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting Hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two orchards provides guidance for the design of Hybridising orchards and isolation requirements to prevent contamination of Seed orchards by external pollen sources.
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Patterns of Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and A. mangium in Vietnam
'Springer Science and Business Media LLC', 2019Co-Authors: Le S, Ce Harwood, Cq Nghiem, Ar Griffin, Re VaillancourtAbstract:AbstractKey message Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of Hybridisation events were found within 60 m from the boundary. ContextUnderstanding pollen dispersal has important implications for breeding and Seed production of pure species and Hybrid Acacia.AimsWe examined patterns of Hybrid production in adjacent clonal Seed orchards of A. auriculiformis and A. mangium in Vietnam.MethodsWe assessed the frequency of Hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of Hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and Hybrid material.ResultsHybrid frequency differed significantly among individual clones (P A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no Hybrids. The level of interspecific Hybridisation declined significantly (P ConclusionPooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting Hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two orchards provides guidance for the design of Hybridising orchards and isolation requirements to prevent contamination of Seed orchards by external pollen sources
Andrea L. Sweigart - One of the best experts on this subject based on the ideXlab platform.
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genetic loci with parent of origin effects cause Hybrid Seed lethality in crosses between mimulus species
New Phytologist, 2016Co-Authors: Austin G Garner, Amanda M. Kenney, Lila Fishman, Andrea L. SweigartAbstract:In flowering plants, F1 Hybrid Seed lethality is a common outcome of crosses between closely related diploid species, but the genetic basis of this early-acting and potentially widespread form of postzygotic reproductive isolation is largely unknown. We intercrossed two closely related species of monkeyflower, Mimulus guttatus and Mimulus tilingii, to characterize the mechanisms and strength of postzygotic reproductive isolation. Then, using a reciprocal backcross design, we performed high-resolution genetic mapping to determine the genetic architecture of Hybrid Seed lethality and directly test for loci with parent-of-origin effects. We found that F1 Hybrid Seed lethality is an exceptionally strong isolating barrier between Mimulus species, with reciprocal crosses producing < 1% viable Seeds. This form of postzygotic reproductive isolation appears to be highly polygenic, indicating that multiple incompatibility loci have accumulated rapidly between these closely related Mimulus species. It is also primarily caused by genetic loci with parent-of-origin effects, suggesting a possible role for imprinted genes in the evolution of Mimulus Hybrid Seed lethality. Our findings suggest that divergence in loci with parent-of-origin effects, which is probably driven by genomic coevolution within lineages, might be an important source of Hybrid incompatibilities between flowering plant species.
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genetic loci with parent of origin effects cause Hybrid Seed lethality between mimulus species
bioRxiv, 2015Co-Authors: Austin G Garner, Amanda M. Kenney, Lila Fishman, Andrea L. SweigartAbstract:The classic finding in both flowering plants and mammals that Hybrid lethality often depends on parent of origin effects suggests that divergence in the underlying loci might be an important source of Hybrid incompatibilities between species. In flowering plants, there is now good evidence from diverse taxa that Seed lethality arising from interploidy crosses is often caused by endosperm defects associated with deregulated imprinted genes. A similar Seed lethality phenotype occurs in many crosses between closely related diploid species, but the genetic basis of this form of early-acting F1 postzygotic reproductive isolation is largely unknown. Here, we show that F1 Hybrid Seed lethality is an exceptionally strong isolating barrier between two closely related Mimulus species, M. guttatus and M. tilingii, with reciprocal crosses producing less than 1% viable Seeds. Using a powerful crossing design and high-resolution genetic mapping, we identify both maternally- and paternally-derived loci that contribute to Hybrid Seed incompatibility. Strikingly, these two sets of loci are largely non-overlapping, providing strong evidence that genes with parent of origin effects are the primary driver of F1 Hybrid Seed lethality between M. guttatus and M. tilingii. We find a highly polygenic basis for both parental components of Hybrid Seed lethality suggesting that multiple incompatibility loci have accumulated to cause strong postzygotic isolation between these closely related species. Our genetic mapping experiment also reveals Hybrid transmission ratio distortion and chromosomal differentiation, two additional correlates of functional and genomic divergence between species.
Re Vaillancourt - One of the best experts on this subject based on the ideXlab platform.
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patterns of Hybrid Seed production in adjacent Seed orchards of acacia auriculiformis and a mangium in vietnam
Annals of Forest Science, 2019Co-Authors: Ce Harwood, Chi Q Nghiem, Rod A Griffin, Re VaillancourtAbstract:Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of Hybridisation events were found within 60 m from the boundary. Understanding pollen dispersal has important implications for breeding and Seed production of pure species and Hybrid Acacia. We examined patterns of Hybrid production in adjacent clonal Seed orchards of A. auriculiformis and A. mangium in Vietnam. We assessed the frequency of Hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of Hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and Hybrid material. Hybrid frequency differed significantly among individual clones (P < 0.001) but not between species (A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no Hybrids. The level of interspecific Hybridisation declined significantly (P < 0.001) with increasing distance, and no Hybrid Seed was produced by trees located more than 116 m from the inter-orchard boundary. Pooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting Hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two orchards provides guidance for the design of Hybridising orchards and isolation requirements to prevent contamination of Seed orchards by external pollen sources.
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Patterns of Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and A. mangium in Vietnam
'Springer Science and Business Media LLC', 2019Co-Authors: Le S, Ce Harwood, Cq Nghiem, Ar Griffin, Re VaillancourtAbstract:AbstractKey message Hybrid Seed production in adjacent Seed orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of Hybridisation events were found within 60 m from the boundary. ContextUnderstanding pollen dispersal has important implications for breeding and Seed production of pure species and Hybrid Acacia.AimsWe examined patterns of Hybrid production in adjacent clonal Seed orchards of A. auriculiformis and A. mangium in Vietnam.MethodsWe assessed the frequency of Hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of Hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and Hybrid material.ResultsHybrid frequency differed significantly among individual clones (P A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no Hybrids. The level of interspecific Hybridisation declined significantly (P ConclusionPooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting Hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two orchards provides guidance for the design of Hybridising orchards and isolation requirements to prevent contamination of Seed orchards by external pollen sources
Amanda M. Kenney - One of the best experts on this subject based on the ideXlab platform.
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genetic loci with parent of origin effects cause Hybrid Seed lethality in crosses between mimulus species
New Phytologist, 2016Co-Authors: Austin G Garner, Amanda M. Kenney, Lila Fishman, Andrea L. SweigartAbstract:In flowering plants, F1 Hybrid Seed lethality is a common outcome of crosses between closely related diploid species, but the genetic basis of this early-acting and potentially widespread form of postzygotic reproductive isolation is largely unknown. We intercrossed two closely related species of monkeyflower, Mimulus guttatus and Mimulus tilingii, to characterize the mechanisms and strength of postzygotic reproductive isolation. Then, using a reciprocal backcross design, we performed high-resolution genetic mapping to determine the genetic architecture of Hybrid Seed lethality and directly test for loci with parent-of-origin effects. We found that F1 Hybrid Seed lethality is an exceptionally strong isolating barrier between Mimulus species, with reciprocal crosses producing < 1% viable Seeds. This form of postzygotic reproductive isolation appears to be highly polygenic, indicating that multiple incompatibility loci have accumulated rapidly between these closely related Mimulus species. It is also primarily caused by genetic loci with parent-of-origin effects, suggesting a possible role for imprinted genes in the evolution of Mimulus Hybrid Seed lethality. Our findings suggest that divergence in loci with parent-of-origin effects, which is probably driven by genomic coevolution within lineages, might be an important source of Hybrid incompatibilities between flowering plant species.
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genetic loci with parent of origin effects cause Hybrid Seed lethality between mimulus species
bioRxiv, 2015Co-Authors: Austin G Garner, Amanda M. Kenney, Lila Fishman, Andrea L. SweigartAbstract:The classic finding in both flowering plants and mammals that Hybrid lethality often depends on parent of origin effects suggests that divergence in the underlying loci might be an important source of Hybrid incompatibilities between species. In flowering plants, there is now good evidence from diverse taxa that Seed lethality arising from interploidy crosses is often caused by endosperm defects associated with deregulated imprinted genes. A similar Seed lethality phenotype occurs in many crosses between closely related diploid species, but the genetic basis of this form of early-acting F1 postzygotic reproductive isolation is largely unknown. Here, we show that F1 Hybrid Seed lethality is an exceptionally strong isolating barrier between two closely related Mimulus species, M. guttatus and M. tilingii, with reciprocal crosses producing less than 1% viable Seeds. Using a powerful crossing design and high-resolution genetic mapping, we identify both maternally- and paternally-derived loci that contribute to Hybrid Seed incompatibility. Strikingly, these two sets of loci are largely non-overlapping, providing strong evidence that genes with parent of origin effects are the primary driver of F1 Hybrid Seed lethality between M. guttatus and M. tilingii. We find a highly polygenic basis for both parental components of Hybrid Seed lethality suggesting that multiple incompatibility loci have accumulated to cause strong postzygotic isolation between these closely related species. Our genetic mapping experiment also reveals Hybrid transmission ratio distortion and chromosomal differentiation, two additional correlates of functional and genomic divergence between species.
