101
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Gil R, Latorre A, Moya A. Evolution of Prokaryote-Animal Symbiosis from a Genomics Perspective. (ENDO)SYMBIOTIC METHANOGENIC ARCHAEA 2010. [DOI: 10.1007/978-3-642-13615-3_11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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102
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Oliver KM, Degnan PH, Burke GR, Moran NA. Facultative symbionts in aphids and the horizontal transfer of ecologically important traits. ANNUAL REVIEW OF ENTOMOLOGY 2010; 55:247-66. [PMID: 19728837 DOI: 10.1146/annurev-ento-112408-085305] [Citation(s) in RCA: 578] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Aphids engage in symbiotic associations with a diverse assemblage of heritable bacteria. In addition to their obligate nutrient-provisioning symbiont, Buchnera aphidicola, aphids may also carry one or more facultative symbionts. Unlike obligate symbionts, facultative symbionts are not generally required for survival or reproduction and can invade novel hosts, based on both phylogenetic analyses and transfection experiments. Facultative symbionts are mutualistic in the context of various ecological interactions. Experiments on pea aphids (Acyrthosiphon pisum) have demonstrated that facultative symbionts protect against entomopathogenic fungi and parasitoid wasps, ameliorate the detrimental effects of heat, and influence host plant suitability. The protective symbiont, Hamiltonella defensa, has a dynamic genome, exhibiting evidence of recombination, phage-mediated gene uptake, and horizontal gene transfer and containing virulence and toxin-encoding genes. Although transmitted maternally with high fidelity, facultative symbionts occasionally move horizontally within and between species, resulting in the instantaneous acquisition of ecologically important traits, such as parasitoid defense.
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Affiliation(s)
- Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
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103
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Caillaud MC, Losey JE. Genetics of color polymorphism in the pea aphid, Acyrthosiphon pisum. JOURNAL OF INSECT SCIENCE (ONLINE) 2010; 10:95. [PMID: 20673119 PMCID: PMC3383419 DOI: 10.1673/031.010.9501] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 02/03/2009] [Indexed: 05/29/2023]
Abstract
The genetic basis of color polymorphism is explored in the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Sternorrhyncha), in which two color morphs have been described (pink or green). Laboratory crosses and a Mendelian genetic analysis reveal that color polymorphism in pea aphids is determined by a single biallelic locus, which we name colorama, with alleles P and p, pink being dominant to green. The putative genotypes are Pp or PP for pink morphs, and pp for green morphs. This locus is shown to be autosomal. Last, there was no evidence of influence of the direction of the cross on color inheritance, thus showing that cytoplasmic effects and/or maternally-inherited symbionts play no role in the inheritance of color polymorphism in pea aphids. The existence of a simple genetic determinism for color polymorphism in a system in which genetic investigation is possible may facilitate investigations on the physiological and molecular mechanisms of genetically-based color morph variation, and the establishment of a link between this locus and fitness in a range of ecological conditions.
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Affiliation(s)
| | - John E. Losey
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
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104
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Degnan PH, Leonardo TE, Cass BN, Hurwitz B, Stern D, Gibbs RA, Richards S, Moran NA. Dynamics of genome evolution in facultative symbionts of aphids. Environ Microbiol 2009; 12:2060-9. [PMID: 21966902 PMCID: PMC2955975 DOI: 10.1111/j.1462-2920.2009.02085.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Aphids are sap-feeding insects that host a range of bacterial endosymbionts including the obligate, nutritional mutualist Buchnera plus several bacteria that are not required for host survival. Among the latter, ‘Candidatus Regiella insecticola’ and ‘Candidatus Hamiltonella defensa’ are found in pea aphids and other hosts and have been shown to protect aphids from natural enemies. We have sequenced almost the entire genome of R. insecticola (2.07 Mbp) and compared it with the recently published genome of H. defensa (2.11 Mbp). Despite being sister species the two genomes are highly rearranged and the genomes only have ∼55% of genes in common. The functions encoded by the shared genes imply that the bacteria have similar metabolic capabilities, including only two essential amino acid biosynthetic pathways and active uptake mechanisms for the remaining eight, and similar capacities for host cell toxicity and invasion (type 3 secretion systems and RTX toxins). These observations, combined with high sequence divergence of orthologues, strongly suggest an ancient divergence after establishment of a symbiotic lifestyle. The divergence in gene sets and in genome architecture implies a history of rampant recombination and gene inactivation and the ongoing integration of mobile DNA (insertion sequence elements, prophage and plasmids).
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Affiliation(s)
- Patrick H Degnan
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. pdegnan@.arizona.edu
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105
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Peccoud J, Simon JC, McLaughlin HJ, Moran NA. Post-Pleistocene radiation of the pea aphid complex revealed by rapidly evolving endosymbionts. Proc Natl Acad Sci U S A 2009; 106:16315-20. [PMID: 19805299 PMCID: PMC2752580 DOI: 10.1073/pnas.0905129106] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Indexed: 11/18/2022] Open
Abstract
Adaptation to different resources has the potential to cause rapid species diversification, but few studies have been able to quantify the time scale of recent adaptive radiations. The pea aphid, Acyrthosiphon pisum, a model of speciation for host-specialized parasites, consists of several biotypes (races or species) living on distinct legume hosts. To document this radiation, we used rapidly evolving sequences from Buchnera, the maternally transmitted bacterial endosymbiont of aphids. Analyses of Buchnera pseudogene sequences revealed that 11 host-associated biotypes sort mostly into distinct matrilines despite low sequence divergence. A calibration based on divergence times of 7 sequenced genomes of Buchnera allowed us to date the last maternal ancestor of these biotypes between 8,000 and 16,000 years, with a burst of diversification at an estimated 3,600-9,500 years. The recency of this diversification, which is supported by microsatellite data, implies that the pea aphid complex ranks among the most rapid adaptive radiations yet documented. This diversification coincides with post-Pleistocene warming and with the domestication and anthropogenic range expansion of several of the legume hosts of pea aphids. Thus, we hypothesize that the new availability or abundance of resources triggered a cascade of divergence events in this newly formed complex.
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Affiliation(s)
- Jean Peccoud
- Unité Mixte de Recherche 1099 Biologie des Organismes et des Populations appliquée à la Protection des Plantes, Institut National de la Recherche Agronomique, Domaine de la Motte BP 35327, 35653 Le Rheu cedex, France; and
| | - Jean-Christophe Simon
- Unité Mixte de Recherche 1099 Biologie des Organismes et des Populations appliquée à la Protection des Plantes, Institut National de la Recherche Agronomique, Domaine de la Motte BP 35327, 35653 Le Rheu cedex, France; and
| | - Heather J. McLaughlin
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85718
| | - Nancy A. Moran
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85718
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106
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Oliver KM, Degnan PH, Hunter MS, Moran NA. Bacteriophages encode factors required for protection in a symbiotic mutualism. Science 2009; 325:992-4. [PMID: 19696350 PMCID: PMC5473335 DOI: 10.1126/science.1174463] [Citation(s) in RCA: 302] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Bacteriophages are known to carry key virulence factors for pathogenic bacteria, but their roles in symbiotic bacteria are less well understood. The heritable symbiont Hamiltonella defensa protects the aphid Acyrthosiphon pisum from attack by the parasitoid Aphidius ervi by killing developing wasp larvae. In a controlled genetic background, we show that a toxin-encoding bacteriophage is required to produce the protective phenotype. Phage loss occurs repeatedly in laboratory-held H. defensa-infected aphid clonal lines, resulting in increased susceptibility to parasitism in each instance. Our results show that these mobile genetic elements can endow a bacterial symbiont with benefits that extend to the animal host. Thus, phages vector ecologically important traits, such as defense against parasitoids, within and among symbiont and animal host lineages.
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Affiliation(s)
- Kerry M Oliver
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
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107
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FRANTZ ADRIEN, CALCAGNO VINCENT, MIEUZET LUCIE, PLANTEGENEST MANUEL, SIMON JEANCHRISTOPHE. Complex trait differentiation between host-populations of the pea aphid Acyrthosiphon pisum (Harris): implications for the evolution of ecological specialisation. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01221.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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108
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NAJAR-RODRÍGUEZ ADRIANAJ, McGRAW ELIZABETHA, HULL CRAIGD, MENSAH ROBERTK, WALTER GIMMEH. The ecological differentiation of asexual lineages of cotton aphids: alate behaviour, sensory physiology, and differential host associations. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01235.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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109
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Evolution and diversity of facultative symbionts from the aphid subfamily Lachninae. Appl Environ Microbiol 2009; 75:5328-35. [PMID: 19542349 DOI: 10.1128/aem.00717-09] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many aphids harbor a variety of endosymbiotic bacteria. The functions of these symbionts can range from an obligate nutritional role to a facultative role in protecting their hosts against environmental stresses. One such symbiont is "Candidatus Serratia symbiotica," which is involved in defense against heat and potentially also in aphid nutrition. Lachnid aphids have been the focus of several recent studies investigating the transition of this symbiont from a facultative symbiont to an obligate symbiont. In a phylogenetic analysis of Serratia symbionts from 51 lachnid hosts, we found that diversity in symbiont morphology, distribution, and function is due to multiple independent origins of symbiosis from ancestors belonging to Serratia and possibly also to evolution within distinct symbiont clades. Our results do not support cocladogenesis of "Ca. Serratia symbiotica" with Cinara subgenus Cinara species and weigh against an obligate nutritional role. Finally, we show that species belonging to the subfamily Lachninae have a high incidence of facultative symbiont infection.
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110
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Abstract
The role of natural selection in speciation, first described by Darwin, has finally been widely accepted. Yet, the nature and time course of the genetic changes that result in speciation remain mysterious. To date, genetic analyses of speciation have focused almost exclusively on retrospective analyses of reproductive isolation between species or subspecies and on hybrid sterility or inviability rather than on ecologically based barriers to gene flow. However, if we are to fully understand the origin of species, we must analyze the process from additional vantage points. By studying the genetic causes of partial reproductive isolation between specialized ecological races, early barriers to gene flow can be identified before they become confounded with other species differences. This population-level approach can reveal patterns that become invisible over time, such as the mosaic nature of the genome early in speciation. Under divergent selection in sympatry, the genomes of incipient species become temporary genetic mosaics in which ecologically important genomic regions resist gene exchange, even as gene flow continues over most of the genome. Analysis of such mosaic genomes suggests that surprisingly large genomic regions around divergently selected quantitative trait loci can be protected from interrace recombination by "divergence hitchhiking." Here, I describe the formation of the genetic mosaic during early ecological speciation, consider the establishment, effects, and transitory nature of divergence hitchhiking around key ecologically important genes, and describe a 2-stage model for genetic divergence during ecological speciation with gene flow.
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Affiliation(s)
- Sara Via
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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111
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Brisson JA, Nuzhdin SV, Stern DL. Similar patterns of linkage disequilibrium and nucleotide diversity in native and introduced populations of the pea aphid, Acyrthosiphon pisum. BMC Genet 2009; 10:22. [PMID: 19470181 PMCID: PMC2695480 DOI: 10.1186/1471-2156-10-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 05/26/2009] [Indexed: 11/10/2022] Open
Abstract
Background The pea aphid, Acyrthosiphon pisum, is an emerging genomic model system for studies of polyphenisms, bacterial symbioses, host-plant specialization, and the vectoring of plant viruses. Here we provide estimates of nucleotide diversity and linkage disequilibrium (LD) in native (European) and introduced (United States) populations of the pea aphid. Because introductions can cause population bottlenecks, we hypothesized that U.S. populations harbor lower levels of nucleotide diversity and higher levels of LD than native populations. Results We sampled four non-coding loci from 24 unique aphid clones from the U. S. (12 from New York and 12 from California) and 24 clones from Europe (12 alfalfa and 12 clover specialists). For each locus, we sequenced approximately 1 kb from two amplicons spaced ~10 kb apart to estimate both short range and longer range LD. We sequenced over 250 kb in total. Nucleotide diversity averaged 0.6% across all loci and all populations. LD decayed slowly within ~1 kb but reached much lower levels over ~10 kb. Contrary to our expectations, neither LD nor nucleotide diversity were significantly different between native and introduced populations. Conclusion Both introduced and native populations of pea aphids exhibit low levels of nucleotide diversity and moderate levels of LD. The introduction of pea aphids to North America has not led to a detectable reduction of nucleotide diversity or increase in LD relative to native populations.
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Affiliation(s)
- Jennifer A Brisson
- Section of Ecology and Evolution, University of California at Davis, Davis, CA, USA.
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112
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Peccoud J, Ollivier A, Plantegenest M, Simon JC. A continuum of genetic divergence from sympatric host races to species in the pea aphid complex. Proc Natl Acad Sci U S A 2009; 106:7495-500. [PMID: 19380742 PMCID: PMC2678636 DOI: 10.1073/pnas.0811117106] [Citation(s) in RCA: 254] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Indexed: 11/18/2022] Open
Abstract
Sympatric populations of insects adapted to different host plants, i.e., host races, are good models to investigate how natural selection can promote speciation in the face of ongoing gene flow. However, host races are documented in very few model systems and their gradual evolution into good species, as assumed under a Darwinian view of species formation, lacks strong empirical support. We aim at resolving this uncertainty by investigating host specialization and gene flow among populations of the pea aphid complex, Acyrthosiphon pisum. Genetic markers and tests of host plant specificity indicate the existence of at least 11 well-distinguished sympatric populations associated with different host plants in Western Europe. Population assignment tests show variable migration and hybridization rates among sympatric populations, delineating 8 host races and 3 possible species. Notably, hybridization correlates negatively with genetic differentiation, forming a continuum of population divergence toward virtually complete speciation. The pea aphid complex thus illustrates how ecological divergence can be sustained among many hybridizing populations and how insect host races blend into species by gradual reduction of gene flow.
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Affiliation(s)
- Jean Peccoud
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1099 BiO3P, Domaine de la Motte, 35653 Le Rheu, France; and
| | - Anthony Ollivier
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1099 BiO3P, Domaine de la Motte, 35653 Le Rheu, France; and
| | - Manuel Plantegenest
- Agrocampus Ouest, Unité Mixte de Recherche 1099 BiO3P, 65 rue de St. Brieuc, 35042 Rennes, France
| | - Jean-Christophe Simon
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1099 BiO3P, Domaine de la Motte, 35653 Le Rheu, France; and
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113
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CARLETTO J, LOMBAERT E, CHAVIGNY P, BRÉVAULT T, LAPCHIN L, VANLERBERGHE-MASUTTI F. Ecological specialization of the aphidAphis gossypiiGlover on cultivated host plants. Mol Ecol 2009; 18:2198-212. [DOI: 10.1111/j.1365-294x.2009.04190.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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114
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Kanbe T, Akimoto SI. Allelic and genotypic diversity in long-term asexual populations of the pea aphid, Acyrthosiphon pisum in comparison with sexual populations. Mol Ecol 2009; 18:801-16. [PMID: 19207245 DOI: 10.1111/j.1365-294x.2008.04077.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Many aphid species exhibit geographical variation in the mode of reproduction that ranges from cyclical parthenogenesis with a sexual phase to obligate parthenogenesis (asexual reproduction). Theoretical studies predict that organisms reproducing asexually should maintain higher allelic diversity per locus but lower genotypic diversity than organisms reproducing sexually. To corroborate this hypothesis, we evaluated genotypic and allelic diversities in the sexual and asexual populations of the pea aphid, Acyrthosiphon pisum (Harris). Microsatellite analysis revealed that populations in central Japan are asexual, whereas populations in northern Japan are obligatorily sexual. No mixed populations were detected in our study sites. Phylogenetic analysis using microsatellite data and mitochondrial cytochrome oxidase subunit I (COI) gene sequences revealed a long history of asexuality in central Japan and negated the possibility of the recent origin of the asexual populations from the sexual populations. Asexual populations exhibited much lower genotypic diversity but higher allelic richness per locus than did sexual populations. Asexual populations consisted of a few predominant clones that were considerably differentiated from one another. Sexual populations on alfalfa, an exotic plant in Japan, were most closely related to asexual populations associated with Vicia sativa L. The alfalfa-associated sexual populations harboured one COI haplotype that was included in the haplotype clade of the asexual populations. Available evidence suggests that the sexuality of the alfalfa-associated populations has recently been restored through the northward migration and colonization of alfalfa by V. sativa-associated lineages. Therefore, our results support the theoretical predictions and provide a new perspective on the origin of sexual populations.
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Affiliation(s)
- Takashi Kanbe
- Systematic Entomology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
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115
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Interactions between vertically transmitted symbionts: cooperation or conflict? Trends Microbiol 2009; 17:95-9. [DOI: 10.1016/j.tim.2008.12.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/25/2008] [Accepted: 12/08/2008] [Indexed: 11/18/2022]
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116
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Vorburger C, Sandrock C, Gouskov A, Castañeda LE, Ferrari J. Genotypic variation and the role of defensive endosymbionts in an all-parthenogenetic host-parasitoid interaction. Evolution 2009; 63:1439-50. [PMID: 19228189 DOI: 10.1111/j.1558-5646.2009.00660.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Models of host-parasite coevolution predict pronounced genetic dynamics if resistance and infectivity are genotype-specific or associated with costs, and if selection is fueled by sufficient genetic variation. We addressed these assumptions in the black bean aphid, Aphis fabae, and its parasitoid Lysiphlebus fabarum. Parasitoid genotypes differed in infectivity and host clones exhibited huge variation for susceptibility. This variation occurred at two levels. Clones harboring Hamiltonella defensa, a bacterial endosymbiont known to protect pea aphids against parasitoids, enjoyed greatly reduced susceptibility, yet clones without H. defensa also exhibited significant variation. Although there was no evidence for genotype-specificity in the H. defensa-free clones' interaction with parasitoids, we found such evidence in clones containing the bacterium. This suggests that parasitoid genotypes differ in their ability to overcome H. defensa, resulting in an apparent host x parasitoid genotype interaction that may in fact be due to an underlying symbiont x parasitoid genotype interaction. Aphid susceptibility to parasitoids correlated negatively with fecundity and rate of increase, due to H. defensa-bearing clones being more fecund on average. Hence, possessing symbionts may also be favorable in the absence of parasitoids, which raises the question why H. defensa does not go to fixation and highlights the need to develop new models to understand the dynamics of endosymbiont-mediated coevolution.
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117
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Najar-Rodríguez AJ, McGraw EA, Mensah RK, Pittman GW, Walter GH. The microbial flora of Aphis gossypii: Patterns across host plants and geographical space. J Invertebr Pathol 2009; 100:123-6. [DOI: 10.1016/j.jip.2008.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 09/19/2008] [Accepted: 10/30/2008] [Indexed: 10/21/2022]
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118
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Oliver KM, Campos J, Moran NA, Hunter MS. Population dynamics of defensive symbionts in aphids. Proc Biol Sci 2008; 275:293-9. [PMID: 18029301 DOI: 10.1098/rspb.2007.1192] [Citation(s) in RCA: 270] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vertically transmitted micro-organisms can increase in frequency in host populations by providing net benefits to hosts. While laboratory studies have identified diverse beneficial effects conferred by inherited symbionts of insects, they have not explicitly examined the population dynamics of mutualist symbiont infection within populations. In the pea aphid, Acyrthosiphon pisum, the inherited facultative symbiont, Hamiltonella defensa, provides protection against parasitism by the wasp, Aphidius ervi. Despite a high fidelity of vertical transmission and direct benefits of infection accruing to parasitized aphids, Hamiltonella remains only at intermediate frequencies in natural populations. Here, we conducted population cage experiments to monitor the dynamics of Hamiltonella and of another common A. pisum symbiont, Serratia symbiotica, in the presence and absence of parasitism. We also conducted fitness assays of Hamiltonella-infected aphids to search for costs to infection in the absence of parasitism. In the population cages, we found that the frequency of A. pisum infected with Hamiltonella increased dramatically after repeated exposure to parasitism by A. ervi, indicating that selection pressures from natural enemies can lead to the increase of particular inherited symbionts in insect populations. In our laboratory fitness assays, we did not detect a cost to infection with Hamiltonella, but in the population cages not exposed to parasitism, we found a significant decline in the frequency of both Hamiltonella and Serratia. The declining frequencies of Hamiltonella-infected aphids in population cages in the absence of parasitism indicate a probable cost to infection and may explain why Hamiltonella remains at intermediate frequencies in natural populations.
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Affiliation(s)
- Kerry M Oliver
- Department of Entomology, University of Arizona,Tucson, AZ 85721, USA.
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119
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PECCOUD J, FIGUEROA CC, SILVA AX, RAMIREZ CC, MIEUZET L, BONHOMME J, STOECKEL S, PLANTEGENEST M, SIMON JC. Host range expansion of an introduced insect pest through multiple colonizations of specialized clones. Mol Ecol 2008; 17:4608-18. [DOI: 10.1111/j.1365-294x.2008.03949.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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120
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Beheregaray LB. Twenty years of phylogeography: the state of the field and the challenges for the Southern Hemisphere. Mol Ecol 2008; 17:3754-74. [PMID: 18627447 DOI: 10.1111/j.1365-294x.2008.03857.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phylogeography is a young, vigorous and integrative field of study that uses genetic data to understand the history of populations. This field has recently expanded into many areas of biology and also into several historical disciplines of Earth sciences. In this review, I present a numerical synthesis of the phylogeography literature based on an examination of over 3000 articles published during the first 20 years of the field (i.e. from 1987 to 2006). Information from several topics needed to evaluate the progress, tendencies and deficiencies of the field is summarized for 10 major groups of organisms and at a global scale. The topics include the geography of phylogeographic surveys, comparative nature of studies, temporal scales and major environments investigated, and genetic markers used. I also identify disparities in research productivity between the developing and the developed world, and propose ways to reduce some of the challenges faced by phylogeographers from less affluent countries. Phylogeography has experienced explosive growth in recent years fuelled by developments in DNA technology, theory and statistical analysis. I argue that the intellectual maturation of the field will eventually depend not only on these recent developments, but also on syntheses of comparative information across different regions of the globe. For this to become a reality, many empirical phylogeographic surveys in regions of the Southern Hemisphere (and in developing countries of the Northern Hemisphere) are needed. I expect the information and views presented here will assist in promoting international collaborative work in phylogeography and in guiding research efforts at both regional and global levels.
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Affiliation(s)
- Luciano B Beheregaray
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
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121
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Ferrari J, Via S, Godfray HCJ. POPULATION DIFFERENTIATION AND GENETIC VARIATION IN PERFORMANCE ON EIGHT HOSTS IN THE PEA APHID COMPLEX. Evolution 2008; 62:2508-24. [DOI: 10.1111/j.1558-5646.2008.00468.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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122
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Abstract
Early in ecological speciation, the genomically localized effects of divergent selection cause heterogeneity among loci in divergence between incipient species. We call this pattern of genomic variability in divergence the 'genetic mosaic of speciation'. Previous studies have used F(ST) outliers as a way to identify divergently selected genomic regions, but the nature of the relationship between outlier loci and quantitative trait loci (QTL) involved in reproductive isolation has not yet been quantified. Here, we show that F(ST) outliers between a pair of incipient species are significantly clustered around QTL for traits that cause ecologically based reproductive isolation. Around these key QTL, extensive 'divergence hitchhiking' occurs because reduced inter-race mating and negative selection decrease the opportunity for recombination between chromosomes bearing different locally adapted QTL alleles. Divergence hitchhiking is likely to greatly increase the opportunity for speciation in populations that are sympatric, regardless of whether initial divergence was sympatric or allopatric. Early in ecological speciation, analyses of population structure, gene flow or phylogeography based on different random or arbitrarily chosen neutral markers should be expected to conflict--only markers in divergently selected genomic regions will reveal the evolutionary history of adaptive divergence and ecologically based reproductive isolation. Species retain mosaic genomes for a very long time, and gene exchange in hybrid zones can vary dramatically among loci. However, in hybridizing species, the genomic regions that affect ecologically based reproductive isolation are difficult to distinguish from regions that have diverged for other reasons.
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Affiliation(s)
- Sara Via
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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123
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Charaabi K, Carletto J, Chavigny P, Marrakchi M, Makni M, Vanlerberghe-Masutti F. Genotypic diversity of the cotton-melon aphid Aphis gossypii (Glover) in Tunisia is structured by host plants. BULLETIN OF ENTOMOLOGICAL RESEARCH 2008; 98:333-41. [PMID: 18257956 DOI: 10.1017/s0007485307005585] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The study of intraspecific variation with respect to host plant utilization in polyphagous insects is crucial for understanding evolutionary patterns of insect-plant interactions. Aphis gossypii (Glover) is a cosmopolitan and extremely polyphagous aphid species. If host plant species or families constitute selective regimes to these aphids, genetic differentiation and host associated adaptation may occur. In this study, we describe the genetic structure of A. gossypii collected in six localities in Tunisia on different vegetable crops, on citrus trees and on Hibiscus. The aim was to determine if the aphid populations are structured in relation to the host plants and if such differentiation is consistent among localities. The genetic variability of A. gossypii samples was examined at eight microsatellite loci. We identified only 11 multilocus genotypes among 559 individuals. Significant deviations from Hardy-Weinberg equilibrium, linkage disequilibria and absence of recombinant genotypes, confirmed that A. gossypii reproduces by continuous apomictic parthenogenesis. Genetic differentiation between localities was not significant, whereas a strong differentiation was observed between host plant families (0.175<FST<0.691). The great majority of aphids exhibited one of three predominant multilocus genotypes that were repeatedly and respectively associated to the three plant families, Cucurbitaceae, Solanaceae and Rutaceae, demonstrating host specialization in A. gossypii. These specialized genotypes were simultaneously found with other clones on Hibiscus, suggesting that this perennial host could act as a refuge plant between two vegetable crop seasons.
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Affiliation(s)
- K Charaabi
- Laboratoire de Génétique Moléculaire, Immunologie et Biotechnologie, Faculté des Sciences de Tunis, 2092 El Manar, Tunisia
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124
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Janson EM, Stireman JO, Singer MS, Abbot P. PHYTOPHAGOUS INSECT–MICROBE MUTUALISMS AND ADAPTIVE EVOLUTIONARY DIVERSIFICATION. Evolution 2008; 62:997-1012. [DOI: 10.1111/j.1558-5646.2008.00348.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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125
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Price BW, Barker NP, Villet MH. Patterns and processes underlying evolutionary significant units in the Platypleura stridula L. species complex (Hemiptera: Cicadidae) in the Cape Floristic Region, South Africa. Mol Ecol 2008; 16:2574-88. [PMID: 17561914 DOI: 10.1111/j.1365-294x.2007.03328.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cicadas have been shown to be useful organisms for examining the effects of distribution, plant association and geographical barriers on gene flow between populations. The cicadas of the Platypleura stridula species complex are restricted to the biologically diverse Cape Floristic Region (CFR) of South Africa. They are thus an excellent study group for elucidating the mechanisms by which hemipteran diversity is generated and maintained in the CFR. Phylogeographical analysis of this species complex using mitochondrial DNA Cytochrome Oxidase I (COI) and ribosomal 16S sequence data, coupled with preliminary morphological and acoustic data, resolves six clades, each of which has specific host-plant associations and distinct geographical ranges. The phylogeographical structure implies simultaneous or near-simultaneous radiation events, coupled with shifts in host-plant associations. When calibrated using published COI and 16S substitution rates typical for related insects, these lineages date back to the late Pliocene - early Pleistocene, coincident with vegetation change, altered drainage patterns and accelerated erosion in response to neotectonic crustal uplift and cyclic Pleistocene climate change, and glaciation-associated changes in climate and sea level.
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Affiliation(s)
- B W Price
- Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa.
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126
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Moya A, Peretó J, Gil R, Latorre A. Learning how to live together: genomic insights into prokaryote-animal symbioses. Nat Rev Genet 2008; 9:218-29. [PMID: 18268509 DOI: 10.1038/nrg2319] [Citation(s) in RCA: 354] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Our understanding of prokaryote-eukaryote symbioses as a source of evolutionary innovation has been rapidly increased by the advent of genomics, which has made possible the biological study of uncultivable endosymbionts. Genomics is allowing the dissection of the evolutionary process that starts with host invasion then progresses from facultative to obligate symbiosis and ends with replacement by, or coexistence with, new symbionts. Moreover, genomics has provided important clues on the mechanisms driving the genome-reduction process, the functions that are retained by the endosymbionts, the role of the host, and the factors that might determine whether the association will become parasitic or mutualistic.
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Affiliation(s)
- Andrés Moya
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Apartado de correos 22085. 46071 València and CIBER de Epidemiología y Salud Pública, Spain.
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127
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Degnan PH, Moran NA. Evolutionary genetics of a defensive facultative symbiont of insects: exchange of toxin-encoding bacteriophage. Mol Ecol 2007; 17:916-29. [PMID: 18179430 DOI: 10.1111/j.1365-294x.2007.03616.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The facultative endosymbiont of aphids, Hamiltonella defensa, kills parasitoid wasp larvae, allowing aphid hosts to survive and reproduce. This protection may depend on toxins that are encoded by the genomes of H. defensa and of its bacteriophage (APSE). Strains of H. defensa vary in degree of protection conferred upon Acyrthosiphon pisum (pea aphid). Although H. defensa is known to undergo some horizontal transmission among aphid maternal lineages, divergence, recombination, and population structure in H. defensa and APSE have not been characterized. We performed a multilocus sequence analysis of 10 bacterial and five phage loci for strains isolated from A. pisum and other aphid species. The H. defensa chromosome was found to be largely clonal, allowing us to generate a well-resolved H. defensa strain phylogeny. In contrast, APSE chromosomes undergo recombination and numerous H. defensa strains have probably lost the phage. Within a set of H. defensa strains that are indistinguishable on the basis of chromosomal genes or restriction digests of chromosomal fragments, loss of APSE is associated with decreased protection, strongly suggesting that APSE-encoded genes contribute to the defensive phenotype. Thus, homologous recombination of APSE genes and sexual transmission of symbionts and phage are likely factors influencing the exchange of ecologically important genes among symbionts. Although H. defensa has been lost, transferred and gained within A. pisum, one subclade of H. defensa appears to be universal within a subclade of the aphid genus Uroleucon, suggesting a transition from facultative, horizontal transmission to strictly vertical inheritance.
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Affiliation(s)
- Patrick H Degnan
- Department of Ecology and Evolutionary Biology, Biosciences West, Room 310, 1041 E. Lowell Street, University of Arizona, Tucson, AZ 85721-0088, USA.
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128
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Weng Y, Azhaguvel P, Michels GJ, Rudd JC. Cross-species transferability of microsatellite markers from six aphid (Hemiptera: Aphididae) species and their use for evaluating biotypic diversity in two cereal aphids. INSECT MOLECULAR BIOLOGY 2007; 16:613-22. [PMID: 17714463 DOI: 10.1111/j.1365-2583.2007.00757.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The abundance and distribution of microsatellites, or simple sequence repeats (SSRs) were explored in the expressed sequence tag (EST) and genomic sequences of the pea aphid, Acyrthosiphon pisum (Harris), and the green peach aphid, Myzus persicae (Sulzer). A total of 108 newly developed, together with 40 published, SSR markers were investigated for their cross-species transferability among six aphid species. Genetic diversity among six greenbug, Schizaphis graminum (Rondani) and two Russian wheat aphid, Diuraphis noxia (Kurdjumov) biotypes was further examined with 67 transferable SSRs. It was found that the pea aphid genome is abundant in SSRs with a unique frequency and distribution of SSR motifs. Cross-species transferability of EST-derived SSRs is dependent on phylogenetic closeness between SSR donor and target species, but is higher than that of genomic SSRs. Neighbor-joining analysis of SSR data revealed host-adapted genetic divergence as well as regional differentiation of greenbug biotypes. The two Russian wheat aphid biotypes are genetically as diverse as the greenbug ones although it was introduced into the USA only 20 years ago. This is the first report of large-scale development of SSR markers in aphids, which are expected to have wide applications in aphid genetic, ecological and evolutionary studies.
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Affiliation(s)
- Y Weng
- Texas A&M University, Agricultural Research and Extension Center, Amarillo, TX 79106, USA.
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129
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Chiel E, Gottlieb Y, Zchori-Fein E, Mozes-Daube N, Katzir N, Inbar M, Ghanim M. Biotype-dependent secondary symbiont communities in sympatric populations of Bemisia tabaci. BULLETIN OF ENTOMOLOGICAL RESEARCH 2007; 97:407-13. [PMID: 17645822 DOI: 10.1017/s0007485307005159] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The sweet potato whitefly, Bemisia tabaci, harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. Bemisia tabaci is a species complex composed of numerous biotypes, which may differ from each other both genetically and biologically. Only the B and Q biotypes have been reported from Israel. Secondary symbiont infection frequencies of Israeli laboratory and field populations of B. tabaci from various host plants were determined by PCR, in order to test for correlation between bacterial composition to biotype and host plant. Hamiltonella was detected only in populations of the B biotype, while Wolbachia and Arsenophonus were found only in the Q biotype (33% and 87% infection, respectively). Rickettsia was abundant in both biotypes. Cardinium and Fritschea were not found in any of the populations. No differences in secondary symbionts were found among host plants within the B biotype; but within the Q biotype, all whiteflies collected from sage harboured both Rickettsia and Arsenophonus, an infection frequency which was significantly higher than those found in association with all other host plants. The association found between whitefly biotypes and secondary symbionts suggests a possible contribution of these bacteria to host characteristics such as insecticide resistance, host range, virus transmission and speciation.
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Affiliation(s)
- E Chiel
- Department of Entomology, Newe-Ya'ar Research Center, ARO, Ramat-Yishai 30095, Israel
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130
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Lozier JD, Roderick GK, Mills NJ. Genetic evidence from mitochondrial, nuclear, and endosymbiont markers for the evolution of host plant associated species in the aphid genus Hyalopterus (Hemiptera: Aphididae). Evolution 2007; 61:1353-67. [PMID: 17542845 DOI: 10.1111/j.1558-5646.2007.00110.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Over the past several decades biologists' fascination with plant-herbivore interactions has generated intensive research into the implications of these interactions for insect diversification. The study of closely related phytophagous insect species or populations from an evolutionary perspective can help illuminate ecological and selective forces that drive these interactions. Here we present such an analysis for aphids in the genus Hyalopterus (Hemiptera: Aphididae), a cosmopolitan group that feeds on plants in the genus Prunus (Rosaceae). Hyalopterus currently contains two recognized species associated with different Prunus species, although the taxonomy and evolutionary history of the group is poorly understood. Using mitochondrial COI sequences, 16S rDNA sequences from the aphid endosymbiont Buchnera aphidicola, and nine microsatellite loci we investigated population structure in Hyalopterus from the most commonly used Prunus host species throughout the Mediterranean as well as in California, where the species H. pruni is an invasive pest. We found three deeply divergent lineages structured in large part by specific associations with plum, almond, and peach trees. There was no evidence that geographic or temporal barriers could explain the overall diversity in the genus. Levels of genetic differentiation are consistent with that typically attributed to aphid species and indicate divergence times older than the domestication of Prunus for agriculture. Interestingly, in addition to their typical hosts, aphids from each of the three lineages were frequently found on apricot trees. Apricot also appears to act as a resource mediated hybrid zone for plum and almond associated lineages. Together, results suggest that host plants have played a role in maintaining host-associated differentiation in Hyalopterus for as long as several million years, despite worldwide movement of host plants and the potential for ongoing hybridization.
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Affiliation(s)
- Jeffrey D Lozier
- Department of Environmental Science, Policy, and Management, 137 Mulford Hall, University of California, Berkeley, CA 94720-3114, USA.
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131
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Ferrari J, Scarborough CL, Godfray HCJ. Genetic variation in the effect of a facultative symbiont on host-plant use by pea aphids. Oecologia 2007; 153:323-9. [PMID: 17415589 DOI: 10.1007/s00442-007-0730-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Accepted: 03/15/2007] [Indexed: 11/28/2022]
Abstract
Ecological specialisation on different host plants occurs frequently among phytophagous insects and is normally assumed to have a genetic basis. However, insects often carry microbial symbionts, which may play a role in the evolution of specialisation. The bacterium Regiella insecticola is a facultative symbiont of pea aphids (Acyrthosiphon pisum) where it is found most frequently in aphid clones feeding on Trifolium giving rise to the hypothesis that it may improve aphid performance on this plant. A study in which R. insecticola was eliminated from a single naturally infected aphid clone supported the hypothesis, but a second involving two aphid clones did not find the same effect. We created a series of new pea aphid-R. insecticola associations by injecting different strains of bacteria into five aphid clones uninfected by symbionts. For all aphid clones, the bacteria decreased the rate at which aphids accepted Vicia faba as a food plant and reduced performance on this plant. Their effect on aphids given Trifolium pratense was more complex: R. insecticola negatively affected acceptance by all aphid clones, had no effect on the performance of four aphid clones, but increased performance of a fifth, thus demonstrating genetic variation in the effect of R. insecticola on pea aphid host use. We discuss how these results may explain the distribution and frequency of this symbiont across different aphid populations.
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Affiliation(s)
- Julia Ferrari
- NERC Centre for Population Biology and Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK.
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132
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Frantz A, Plantegenest M, Simon JC. Temporal habitat variability and the maintenance of sex in host populations of the pea aphid. Proc Biol Sci 2007; 273:2887-91. [PMID: 17015368 PMCID: PMC1664625 DOI: 10.1098/rspb.2006.3665] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolutionary maintenance of sex, despite competition from asexual reproduction, has long intrigued the evolutionary biologists owing to its numerous apparent short-term costs. In aphids, winter climate is expected to determine the maintenance of sexual lineages in the high latitude zones owing to their exclusive ability to produce frost-resistant eggs. However, diverse reproductive modes may coexist at a local scale where climatic influence is counteracted by microgeographical factors. In this study, we tested the influence of local habitat characteristics on regional coexistence of reproductive modes in the pea aphid, Acyrthosiphon pisum. In the laboratory, the induction of sexual morph production of many pea aphid genotypes from the local fields of annual (pea and faba bean) and perennial (alfalfa and red clover) crops in Western France indicated that A. pisum lineages from annual crops had a significantly higher investment in sexual reproduction than A. pisum lineages from the perennial hosts. We propose that temporal habitat variability exerts a selective pressure to maintain the sexual reproduction in A. pisum. The ecological and evolutionary consequences of the association between the mode of reproduction and the host population on gene flow restriction and on ecological specialization are discussed.
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133
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Reynolds DR, Chapman JW, Harrington R. The migration of insect vectors of plant and animal viruses. Adv Virus Res 2006; 67:453-517. [PMID: 17027687 DOI: 10.1016/s0065-3527(06)67012-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- D R Reynolds
- Natural Resources Institute, University of Greenwich Chatham Maritime, Kent ME4 4TB, United Kingdom
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134
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Henry LM, Roitberg BD, Gillespie DR. Covariance of phenotypically plastic traits induces an adaptive shift in host selection behaviour. Proc Biol Sci 2006; 273:2893-9. [PMID: 17015365 PMCID: PMC1664631 DOI: 10.1098/rspb.2006.3672] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 07/05/2006] [Indexed: 11/12/2022] Open
Abstract
Flexibility in adult body size allows generalist parasitoids to use many host species at a cost of producing a range of adult sizes. Consequently, host selection behaviour must also maintain a level of flexibility as adult size is related to capture efficiency. In the present study, we investigated covariance of two plastic traits--size at pupation and host size selection behaviour-using Aphidius ervi reared on either Acyrthosiphon pisum or Aulacorthum solani, generating females of disparate sizes. Natal host was shown to change the ranking of perceived host quality with relation to host size. Parasitoids preferentially attacked hosts that corresponded to the size of the second instar of their natal host species. This resulted in optimal host selection behaviour when parasitoids were exposed to the same host species from which they emerged. Parasitoid size was positively correlated with host size preference, indicating that females use relative measurements when selecting suitable hosts. These coadapted gene complexes allow generalist parasitoids to effectively use multiple host species over several generations. However, the fixed nature of the behavioural response, within a parasitoid's lifetime, suggests that these traits may have evolved in a patchy host species environment.
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Affiliation(s)
- Lee M Henry
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6 Canada.
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135
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Leonardo TE, Mondor EB. Symbiont modifies host life-history traits that affect gene flow. Proc Biol Sci 2006; 273:1079-84. [PMID: 16600884 PMCID: PMC1560252 DOI: 10.1098/rspb.2005.3408] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolution of herbivore-host plant specialization requires low levels of gene flow between populations on alternate plant species. Accordingly, selection for host plant specialization is most effective when genotypes have minimal exposure to, and few mating opportunities with individuals from, alternate habitats. Maternally transmitted bacterial symbionts are common in insect herbivores and can influence host fecundity under a variety of conditions. Symbiont-mediated effects on host life-history strategies, however, are largely unknown. Here, we show that the facultative bacterial symbiont Candidatus Regiella insecticola strikingly alters both dispersal and mating in the pea aphid, Acyrthosiphon pisum. Pea aphids containing Regiella produced only half the number of winged offspring in response to crowding and, for two out of three aphid lineages, altered the timing of sexual reproduction in response to conditions mimicking seasonal changes, than did aphids lacking Regiella. These symbiont-associated changes in dispersal and mating are likely to have played a key role in the initiation of genetic differentiation and in the evolution of pea aphid-host plant specialization. As symbionts are widespread in insects, symbiont-induced life history changes may have promoted specialization, and potentially speciation, in many organisms.
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Affiliation(s)
- Teresa E Leonardo
- Department of Ecology & Evolutionary Biology, Princeton University, NJ 08544, USA.
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136
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Ferrari J, Godfray HCJ, Faulconbridge AS, Prior K, Via S. POPULATION DIFFERENTIATION AND GENETIC VARIATION IN HOST CHOICE AMONG PEA APHIDS FROM EIGHT HOST PLANT GENERA. Evolution 2006. [DOI: 10.1111/j.0014-3820.2006.tb00502.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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137
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Abstract
Insects comprise the largest species composition in the entire animal kingdom and possess a vast undiscovered genetic diversity and gene pool that can be better explored using molecular marker techniques. Current trends of application of DNA marker techniques in diverse domains of insect ecological studies show that mitochondrial DNA (mtDNA), microsatellites, random amplified polymorphic DNA (RAPD), expressed sequence tags (EST) and amplified fragment length polymorphism (AFLP) markers have contributed significantly for progresses towards understanding genetic basis of insect diversity and for mapping medically and agriculturally important genes and quantitative trait loci in insect pests. Apart from these popular marker systems, other novel approaches including transposon display, sequence-specific amplification polymorphism (S-SAP), repeat-associated polymerase chain reaction (PCR) markers have been identified as alternate marker systems in insect studies. Besides, whole genome microarray and single nucleotide polymorphism (SNP) assays are becoming more popular to screen genome-wide polymorphisms in fast and cost effective manner. However, use of such methodologies has not gained widespread popularity in entomological studies. The current study highlights the recent trends of applications of molecular markers in insect studies and explores the technological advancements in molecular marker tools and modern high throughput genotyping methodologies that may be applied in entomological researches for better understanding of insect ecology at molecular level.
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Affiliation(s)
- Susanta K Behura
- Department of Entomology, 505 S Goodwin Avenue, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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138
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Russell JA, Moran NA. Costs and benefits of symbiont infection in aphids: variation among symbionts and across temperatures. Proc Biol Sci 2006; 273:603-10. [PMID: 16537132 PMCID: PMC1560055 DOI: 10.1098/rspb.2005.3348] [Citation(s) in RCA: 290] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Symbiosis is prevalent throughout the tree of life and has had a significant impact on the ecology and evolution of many bacteria and eukaryotes. The benevolence of symbiotic interactions often varies with the environment, and such variation is expected to play an important role in shaping the prevalence and distributions of symbiosis throughout nature. In this study, we examine how the fitness of aphids is influenced by infection with one of three maternally transmitted bacteria, 'Candidatus Serratia symbiotica', 'Candidatus Hamiltonella defensa' and 'Candidatus Regiella insecticola', addressing how symbiont benevolence varies with temperature. We find that the effects of these 'secondary' symbionts on Acyrthosiphon pisum depend on when and whether aphids are exposed to a brief period of heat shock. We also demonstrate that symbionts--even closely related isolates--vary in their effects on hosts. Our results indicate similar effects of S. symbiotica and H. defensa in conferring tolerance to high temperatures and a liability of R. insecticola under these same conditions. These findings reveal a role for heritable symbionts in the adaptation of aphids to their abiotic environments and add to an expanding body of knowledge on the adaptive significance of symbiosis.
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Affiliation(s)
- Jacob A Russell
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA.
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139
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Frantz A, Plantegenest M, Mieuzet L, Simon JC. Ecological specialization correlates with genotypic differentiation in sympatric host-populations of the pea aphid. J Evol Biol 2006; 19:392-401. [PMID: 16599915 DOI: 10.1111/j.1420-9101.2005.01025.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pea aphid, Acyrthosiphon pisum, encompasses distinct host races specialized on various Fabaceae species, but the extent of genetic divergence associated with ecological specialization varies greatly depending on plant and geographic origins of aphid populations. Here, we studied the genetic structure of French sympatric pea aphid populations collected on perennial (pea and faba bean) and annual (alfalfa and red clover) hosts using 14 microsatellite loci. Classical and Bayesian population genetics analyses consistently identified genetic clusters mostly related to plant origin: the pea/faba bean cluster was highly divergent from the red clover and the alfalfa ones, indicating they represent different stages along the continuum of genetic differentiation. Some genotypes were assigned to a cluster differing from the one expected from their plant origin while others exhibited intermediate genetic characteristics. These results suggest incomplete barriers to gene flow. However, this limited gene flow seems insufficient to prevent ecological specialization and genetic differentiation in sympatry.
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Affiliation(s)
- A Frantz
- UMR INRA/Agrocampus Rennes Biologie des Organismes et des Populations appliquée à la Protection des Plantes, BP 35327--Domaine de la Motte-au-Vicomte, 35653--Le Rheu, Cedex, France.
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140
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Russell JA, Moran NA. Horizontal transfer of bacterial symbionts: heritability and fitness effects in a novel aphid host. Appl Environ Microbiol 2006; 71:7987-94. [PMID: 16332777 PMCID: PMC1317397 DOI: 10.1128/aem.71.12.7987-7994.2005] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of several bacterial lineages are known only as symbionts of insects and move among hosts through maternal transmission. Such vertical transfer promotes strong fidelity within these associations, favoring the evolution of microbially mediated effects that improve host fitness. However, phylogenetic evidence indicates occasional horizontal transfer among different insect species, suggesting that some microbial symbionts retain a generalized ability to infect multiple hosts. Here we examine the abilities of three vertically transmitted bacteria from the Gammaproteobacteria to infect and spread within a novel host species, the pea aphid, Acyrthosiphon pisum. Using microinjection, we transferred symbionts from three species of natural aphid hosts into a common host background, comparing transmission efficiencies between novel symbionts and those naturally infecting A. pisum. We also examined the fitness effects of two novel symbionts to determine whether they should persist under natural selection acting at the host level. Our results reveal that these heritable bacteria vary in their capacities to utilize A. pisum as a host. One of three novel symbionts failed to undergo efficient maternal transmission in A. pisum, and one of the two efficiently transmitted bacteria depressed aphid growth rates. Although these findings reveal that negative fitness effects and low transmission efficiency can prevent the establishment of a new infection following horizontal transmission, they also indicate that some symbionts can overcome these obstacles, accounting for their widespread distributions across aphids and related insects.
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Affiliation(s)
- Jacob A Russell
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology Labs, Harvard University, 26 Oxford St., Cambridge, MA 02138, USA.
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141
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De Barro PJ. Genetic structure of the whitefly Bemisia tabaci in the Asia-Pacific region revealed using microsatellite markers. Mol Ecol 2006; 14:3695-718. [PMID: 16202090 DOI: 10.1111/j.1365-294x.2005.02700.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bemisia tabaci (Hemiptera: Aleyrodidae) is a haplo-diploid species of sap-feeding insect belonging to the group of insects commonly known as whiteflies. From earlier analyses of mitochondrial and ribosomal markers it has been concluded that in the Asia-Pacific region there were three major indigenous races as well as a large collection of genotypes with no clear association with any race. This new study uses 15 microsatellite loci and demonstrates that the indigenous Asia-Pacific genotypes can be split into six genetic populations with little or no gene flow between them. These bare only superficial similarity to the mitochondrial and ribosomal defined races. Moreover, four of the six can be further split into two subpopulations that again show little evidence gene flow between them. While the patterns reflect a strong geographical structure, physical barriers alone cannot explain all the observed structure. Differential host-plant utilization explained some of the substructure, but could not explain the overall structure. The roles of mating interference and Wolbachia in developing the genetic structure are considered. The lack of gene flow between genetic populations and some subpopulations further suggests that the barriers were either sufficiently impermeable to immigration or that reproductive isolation and competitive interactions were sufficiently strong to prevent gene flow. If the latter is the case, it suggests that there may be as many as 10 morphologically indistinguishable species indigenous to the Asia-Pacific region.
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Affiliation(s)
- P J De Barro
- CSIRO Entomology, 120 Meiers Road, Indooroopilly 4068, Australia.
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142
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Ferrari J, Godfray HCJ, Faulconbridge AS, Prior K, Via S. POPULATION DIFFERENTIATION AND GENETIC VARIATION IN HOST CHOICE AMONG PEA APHIDS FROM EIGHT HOST PLANT GENERA. Evolution 2006. [DOI: 10.1554/06-024.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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143
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The maintenance of intraspecific biodiversity: the interplay of selection on resource use and on natural enemy resistance in the pea aphid. Ecol Res 2005. [DOI: 10.1007/s11284-005-0136-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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144
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Darby AC, Chandler SM, Welburn SC, Douglas AE. Aphid-symbiotic bacteria cultured in insect cell lines. Appl Environ Microbiol 2005; 71:4833-9. [PMID: 16085881 PMCID: PMC1183350 DOI: 10.1128/aem.71.8.4833-4839.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cells and tissues of many aphids contain bacteria known as "secondary symbionts," which under specific environmental circumstances may be beneficial to the host insect. Such symbiotic bacteria are traditionally described as intractable to cultivation in vitro. Here we show that two types of aphid secondary symbionts, known informally as T type and U type, can be cultured and maintained in three insect cell lines. The identities of the cultured bacteria were confirmed by PCR with sequencing of 16S rRNA gene fragments and fluorescence in situ hybridization. In cell lines infected with bacteria derived from aphids harboring both T type and U type, the U type persisted, while the T type was lost. We suggest that the two bacteria persist in aphids because competition between them is limited by differences in tropism for insect tissues or cell types. The culture of these bacteria in insect cell lines provides a new and unique research opportunity, offering a source of unibacterial material for genomic studies and a model system to investigate the interactions between animal cells and bacteria. We propose the provisional taxon names "Candidatus Consessoris aphidicola" for T type and "Candidatus Adiaceo aphidicola" for U type.
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Affiliation(s)
- A C Darby
- Centre for Infectious Diseases, College of Medicine and Veterinary Medicine, The University of Edinburgh, Easter Bush, Edinburgh EH25 9RG, Scotland, United Kingdom.
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145
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Vialatte A, Dedryver CA, Simon JC, Galman M, Plantegenest M. Limited genetic exchanges between populations of an insect pest living on uncultivated and related cultivated host plants. Proc Biol Sci 2005; 272:1075-82. [PMID: 16024367 PMCID: PMC1599878 DOI: 10.1098/rspb.2004.3033] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Habitats in agroecosystems are ephemeral, and are characterized by frequent disturbances forcing pest species to successively colonize various hosts belonging either to the cultivated or to the uncultivated part of the agricultural landscape. The role of wild habitats as reservoirs or refuges for the aphid Sitobion avenae that colonize cultivated fields was assessed by investigating the genetic structure of populations collected on both cereal crops (wheat, barley and oat) and uncultivated hosts (Yorkshire fog, cocksfoot, bulbous oatgrass and tall oatgrass) in western France. Classical genetic analyses and Bayesian clustering algorithms indicate that genetic differentiation is high between populations collected on uncultivated hosts and on crops, revealing a relatively limited gene flow between the uncultivated margins and the cultivated part of the agroecosystem. A closer genetic relatedness was observed between populations living on plants belonging to the same tribe (Triticeae, Poeae and Aveneae tribes) where aphid genotypes appeared not to be specialized on a single host, but rather using a group of related plant species. Causes of this ecological differentiation and its implications for integrated pest management of S. avenae as cereals pest are discussed.
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Affiliation(s)
- Aude Vialatte
- INRA/Agrocampus Rennes, Unité Mixte de Recherche Biologie des Organismes et des Populations appliquées à la Protection des Plantes (UMR BiO3P), Equipe Biologie et Génétique des Population d'InsectesDomaine de la Motte, 35653 Le Rheu, France
- Makhteshim Agan France12 Bd des Iles, 92441 Issy Les Moulineaux Cedex, France
| | - Charles-Antoine Dedryver
- INRA/Agrocampus Rennes, Unité Mixte de Recherche Biologie des Organismes et des Populations appliquées à la Protection des Plantes (UMR BiO3P), Equipe Biologie et Génétique des Population d'InsectesDomaine de la Motte, 35653 Le Rheu, France
| | - Jean-Christophe Simon
- INRA/Agrocampus Rennes, Unité Mixte de Recherche Biologie des Organismes et des Populations appliquées à la Protection des Plantes (UMR BiO3P), Equipe Biologie et Génétique des Population d'InsectesDomaine de la Motte, 35653 Le Rheu, France
| | - Marina Galman
- INRA/Agrocampus Rennes, Unité Mixte de Recherche Biologie des Organismes et des Populations appliquées à la Protection des Plantes (UMR BiO3P), Equipe Biologie et Génétique des Population d'InsectesDomaine de la Motte, 35653 Le Rheu, France
| | - Manuel Plantegenest
- INRA/Agrocampus Rennes, Unité Mixte de Recherche Biologie des Organismes et des Populations appliquées à la Protection des Plantes (UMR BiO3P), Equipe Biologie et Génétique des Population d'InsectesDomaine de la Motte, 35653 Le Rheu, France
- Author for correspondence ()
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146
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Sakurai M, Koga R, Tsuchida T, Meng XY, Fukatsu T. Rickettsia symbiont in the pea aphid Acyrthosiphon pisum: novel cellular tropism, effect on host fitness, and interaction with the essential symbiont Buchnera. Appl Environ Microbiol 2005; 71:4069-75. [PMID: 16000822 PMCID: PMC1168972 DOI: 10.1128/aem.71.7.4069-4075.2005] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Accepted: 02/02/2005] [Indexed: 11/20/2022] Open
Abstract
In natural populations of the pea aphid Acyrthosiphon pisum, a facultative bacterial symbiont of the genus Rickettsia has been detected at considerable infection frequencies worldwide. We investigated the effects of the Rickettsia symbiont on the host aphid and also on the coexisting essential symbiont Buchnera. In situ hybridization revealed that the Rickettsia symbiont was specifically localized in two types of host cells specialized for endosymbiosis: secondary mycetocytes and sheath cells. Electron microscopy identified bacterial rods, about 2 mum long and 0.5 mum thick, in sheath cells of Rickettsia-infected aphids. Virus-like particles were sometimes observed in association with the bacterial cells. By an antibiotic treatment, we generated Rickettsia-infected and Rickettsia-eliminated aphid strains with an identical genetic background. Comparison of these strains revealed that Rickettsia infection negatively affected some components of the host fitness. Quantitative PCR analysis of the bacterial population dynamics identified a remarkable interaction between the coexisting symbionts: Buchnera population was significantly suppressed in the presence of Rickettsia, particularly at the young adult stage, when the aphid most actively reproduces. On the basis of these results, we discussed the possible mechanisms that enable the prevalence of Rickettsia infection in natural host populations in spite of the negative fitness effects observed in the laboratory.
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Affiliation(s)
- Makiko Sakurai
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan.
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147
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Tsuchida T, Koga R, Meng XY, Matsumoto T, Fukatsu T. Characterization of a facultative endosymbiotic bacterium of the pea aphid Acyrthosiphon pisum. MICROBIAL ECOLOGY 2005; 49:126-133. [PMID: 15690225 DOI: 10.1007/s00248-004-0216-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Accepted: 02/09/2004] [Indexed: 05/24/2023]
Abstract
The pea aphid U-type symbiont (PAUS) was investigated to characterize its microbiological properties. Fluorescence in situ hybridization (FISH) and electron microscopy revealed that PAUS was a rod-shaped bacterium found in three different locations in the body of the pea aphid Acyrthosiphon pisum: sheath cells, secondary mycetocytes, and hemolymph. Artificial transfer experiments revealed that PAUS could establish stable infection and vertical transmission when introduced into uninfected pea aphids. When 28 aphid species collected in Japan were subjected to a diagnostic PCR assay, four species of the subfamily Aphidinae (Aphis citricola, Aphis nerii, Macrosiphum avenae, and Uroleucon giganteus) and a species of the subfamily Pemphiginae (Colopha kansugei) were identified to be PAUS-positive. The sporadic incidences of PAUS infection without reflecting the aphid phylogeny can be best explained by occasional horizontal transfers of the symbiont across aphid lineages.
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Affiliation(s)
- T Tsuchida
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST),Tsukuba 305-8566, Japan
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148
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Abstract
The development of molecular techniques for the study of uncultured bacteria allowed the extensive study of the widespread association between insects and intracellular symbiotic bacteria. Most of the bacterial endosymbionts involved in such associations are gamma-proteobacteria, closely related to Escherichia coli. In recent years, five genomes from insect endosymbionts have been sequenced, allowing the performance of extensive genome comparative analysis that, as a complement of phylogenetic studies, and analysis on individual genes, can help to understand the different traits of this particular association, including how the symbiotic process is established, the explanation of the special features of these microbial genomes, the bases of this intimate association and the possible future that awaits the endosymbionts with extremely reduced genomes.
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Affiliation(s)
- Rosario Gil
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva and Departament de Genètica, Universitat de València, Apartado Postal 22085, 46071 Valencia, Spain.
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149
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Gómez-Valero L, Soriano-Navarro M, Pérez-Brocal V, Heddi A, Moya A, García-Verdugo JM, Latorre A. Coexistence of Wolbachia with Buchnera aphidicola and a secondary symbiont in the aphid Cinara cedri. J Bacteriol 2004; 186:6626-33. [PMID: 15375144 PMCID: PMC516615 DOI: 10.1128/jb.186.19.6626-6633.2004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Intracellular symbiosis is very common in the insect world. For the aphid Cinara cedri, we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboring Buchnera aphidicola, the primary endosymbiont of aphids, C. cedri harbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an alpha-proteobacterium that belongs to the Wolbachia genus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA sequences, we have shown that Wolbachia was represented by only a few minute bacteria surrounding the S symbionts. Moreover, the observed B. aphidicola and the S symbionts had similar sizes and were housed in separate specific bacterial cells, the bacteriocytes. Interestingly, in contrast to the case for all aphids examined thus far, the S symbionts were shown to occupy a similarly sized or even larger bacteriocyte space than B. aphidicola. These findings, along with the facts that C. cedri harbors the B. aphidicola strain with the smallest bacterial genome and that the S symbionts infect all Cinara spp. analyzed so far, suggest the possibility of bacterial replacement in these species.
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Affiliation(s)
- Laura Gómez-Valero
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, València, Spain
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150
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BIRKLE LM, MINTO LB, WALTERS KFA, DOUGLAS AE. Microbial genotype and insect fitness in an aphid-bacterial symbiosis. Funct Ecol 2004. [DOI: 10.1111/j.0269-8463.2004.00871.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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