scholarly journals Unravelling the genomic basis and evolution of the pea aphid male wing dimorphism

2017 ◽  
Author(s):  
Binshuang Li ◽  
Ryan D. Bickel ◽  
Benjamin J. Parker ◽  
Neetha Nanoth Vellichirammal ◽  
Mary Grantham ◽  
...  
Keyword(s):  
Complex Traits ◽  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Specific Gene ◽  
Regulatory Change ◽  
Wing Dimorphism ◽  
Wing Polymorphism ◽  
Male Wing ◽  
Mechanistic Basis

SummaryWing dimorphisms have long served as models for examining the ecological and evolutionary tradeoffs associated with alternative morphologies [1], yet the mechanistic basis of morph determination remains largely unknown. Here we investigate the genetic basis of the pea aphid (Acyrthosiphon pisum) wing dimorphism, wherein males exhibit one of two alternative morphologies that differ dramatically in a set of correlated traits that inclused the presence or absence of wings [2-4]. Unlike the environmentally-induced asexual female aphid wing polyphenism [5], the male wing polymorphism is genetically determined by a single uncharacterized locus on the X chromosome called aphicarus (“aphid” plus “Icarus”, api) [6, 7]. Using recombination and association mapping, we localized api to a 130kb region of the pea aphid genome. No nonsynonymous variation in coding sequences strongly associated with the winged and wingless phenotypes, indicating that api is likely a regulatory change. Gene expression level profiling revealed an aphid-specific gene from the region expressed at higher levels in winged male embryos, coinciding with the expected stage of api action. Comparison of the api region across biotypes (pea aphid populations specialized to different host plants that began diverging ~16,000 years ago [8, 9]) revealed that the two alleles were likely present prior to biotype diversification. Moreover, we find evidence for a recent selective sweep of a wingless allele since the biotypes diversified. In sum, this study provides insight into how adaptive, complex traits evolve within and across natural populations.

scholarly journals A large genomic insertion containing a duplicated follistatin gene is linked to the pea aphid male wing dimorphism

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Binshuang Li ◽  
Ryan D Bickel ◽  
Benjamin J Parker ◽  
Omid Saleh Ziabari ◽  
Fangzhou Liu ◽  
...  
Keyword(s):  
Acyrthosiphon Pisum ◽  
Balancing Selection ◽  
Genomic Region ◽  
Pea Aphid ◽  
Wing Dimorphism ◽  
Alternative Phenotypes ◽  
Long Read ◽  
Male Wing ◽  
Strong Candidate ◽  
Trait Difference

Wing dimorphisms have long served as models for examining the ecological and evolutionary tradeoffs associated with alternative phenotypes. Here, we investigated the genetic cause of the pea aphid (Acyrthosiphon pisum) male wing dimorphism, wherein males exhibit one of two morphologies that differ in correlated traits that include the presence or absence of wings. We mapped this trait difference to a single genomic region and, using third generation, long-read sequencing, we identified a 120 kb insertion in the wingless allele. This insertion includes a duplicated follistatin gene, which is a strong candidate gene in the minimal mapped interval to cause the dimorphism. We found that both alleles were present prior to pea aphid biotype lineage diversification, we estimated that the insertion occurred millions of years ago, and we propose that both alleles have been maintained in the species, likely due to balancing selection.

scholarly journals A sex-linked locus controls wing polymorphism in males of the pea aphid, Acyrthosiphon pisum (Harris)

Heredity ◽  
2002 ◽  
Vol 89 (5) ◽  
pp. 346-352 ◽  
Author(s):  
M C Caillaud ◽  
M Boutin ◽  
C Braendle ◽  
J-C Simon
Keyword(s):  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Wing Polymorphism

scholarly journals Intraspecific variation in symbiont density in an insect-microbe symbiosis

2020 ◽  
Author(s):  
Benjamin J. Parker ◽  
Jan Hrček ◽  
Ailsa H.C. McLean ◽  
Jennifer A. Brisson ◽  
H. Charles J. Godfray
Keyword(s):  
Intraspecific Variation ◽  
Fungal Pathogens ◽  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Optimal Density ◽  
Evolutionary Forces ◽  
Standing Variation ◽  
Dramatic Decline

AbstractMany insects host vertically-transmitted microbes, which can confer benefits to their hosts but are costly to maintain and regulate. A key feature of these symbioses is variation: for example, symbiont density can vary among host and symbiont genotypes. However, the evolutionary forces maintaining this variation remain unclear. We studied variation in symbiont density using the pea aphid (Acyrthosiphon pisum) and the bacterium Regiella insecticola, a symbiont that can protect its host against fungal pathogens. We found that relative symbiont density varies both between two Regiella phylogenetic clades and among aphid ‘biotypes’. Higher-density symbiont infections are correlated with stronger survival costs, but variation in density has little effect on the protection Regiella provides against fungus. Instead, we found that in some aphid genotypes, a dramatic decline in symbiont density precedes the loss of a symbiont infection. Together, our data suggest that the optimal density of a symbiont infection is likely different from the perspective of aphid and microbial fitness. Regiella might prevent loss by maintaining high within-host densities, but hosts do not appear to benefit from higher symbiont numbers and may be advantaged by losing costly symbionts in certain environments. The standing variation in symbiont density observed in natural populations could therefore be maintained by antagonistic coevolutionary interactions between hosts and their symbiotic microbes.

scholarly journals Spiroplasma Symbiont of the Pea Aphid, Acyrthosiphon pisum (Insecta: Homoptera)

2001 ◽  
Vol 67 (3) ◽  
pp. 1284-1291 ◽  
Author(s):  
Takema Fukatsu ◽  
Tsutomu Tsuchida ◽  
Naruo Nikoh ◽  
Ryuichi Koga
Keyword(s):  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Laboratory Strain ◽  
Pea Aphid ◽  
Endosymbiotic Bacterium ◽  
Negative Effects ◽  
Central Japan ◽  
16S Ribosomal Dna ◽  
Molecular Phylogenetic ◽  
Successive Generations

ABSTRACT From a laboratory strain of the pea aphid, Acyrthosiphon pisum, we discovered a previously unknown facultative endosymbiotic bacterium. Molecular phylogenetic analysis based on 16S ribosomal DNA revealed that the bacterium is a member of the genusSpiroplasma. The Spiroplasma organism showed stable vertical transmission through successive generations of the host. Injection of hemolymph from infected insects into uninfected insects established a stable infection in the recipients. TheSpiroplasma symbiont exhibited negative effects on growth, reproduction, and longevity of the host, particularly in older adults. Of 58 clonal strains of A. pisum established from natural populations in central Japan, 4 strains possessed theSpiroplasma organism.

scholarly journals Rickettsia Symbiont in the Pea Aphid Acyrthosiphon pisum: Novel Cellular Tropism, Effect on Host Fitness, and Interaction with the Essential Symbiont Buchnera

2005 ◽  
Vol 71 (7) ◽  
pp. 4069-4075 ◽  
Author(s):  
Makiko Sakurai ◽  
Ryuichi Koga ◽  
Tsutomu Tsuchida ◽  
Xian-Ying Meng ◽  
Takema Fukatsu
Keyword(s):  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Host Cells ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Host Fitness ◽  
Host Aphid ◽  
Sheath Cells

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 μm long and 0.5 μm 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.

scholarly journals Selection following Gene Duplication Shapes Recent Genome Evolution in the Pea Aphid Acyrthosiphon pisum

2020 ◽  
Vol 37 (9) ◽  
pp. 2601-2615 ◽  
Author(s):  
Rosa Fernández ◽  
Marina Marcet-Houben ◽  
Fabrice Legeai ◽  
Gautier Richard ◽  
Stéphanie Robin ◽  
...  
Keyword(s):  
Gene Duplication ◽  
Acyrthosiphon Pisum ◽  
High Capacity ◽  
Chromatin Accessibility ◽  
Pea Aphid ◽  
Specific Gene ◽  
Gene Duplications ◽  
Evolutionary Mechanisms ◽  
Ancestral Gene ◽  
Species Specific

Abstract Ecology of insects is as wide as their diversity, which reflects their high capacity of adaptation in most of the environments of our planet. Aphids, with over 4,000 species, have developed a series of adaptations including a high phenotypic plasticity and the ability to feed on the phloem sap of plants, which is enriched in sugars derived from photosynthesis. Recent analyses of aphid genomes have indicated a high level of shared ancestral gene duplications that might represent a basis for genetic innovation and broad adaptations. In addition, there are a large number of recent, species-specific gene duplications whose role in adaptation remains poorly understood. Here, we tested whether duplicates specific to the pea aphid Acyrthosiphon pisum are related to genomic innovation by combining comparative genomics, transcriptomics, and chromatin accessibility analyses. Consistent with large levels of neofunctionalization, we found that most of the recent pairs of gene duplicates evolved asymmetrically, showing divergent patterns of positive selection and gene expression. Genes under selection involved a plethora of biological functions, suggesting that neofunctionalization and tissue specificity, among other evolutionary mechanisms, have orchestrated the evolution of recent paralogs in the pea aphid and may have facilitated host–symbiont cooperation. Our comprehensive phylogenomics analysis allowed us to tackle the history of duplicated genes to pave the road toward understanding the role of gene duplication in ecological adaptation.

scholarly journals Elucidation of the Transmission Patterns of an Insect-Borne Bacterium

2003 ◽  
Vol 69 (8) ◽  
pp. 4403-4407 ◽  
Author(s):  
A. C. Darby ◽  
A. E. Douglas
Keyword(s):  
Vertical Transmission ◽  
Acyrthosiphon Pisum ◽  
Deterministic Model ◽  
Transmission Rate ◽  
Horizontal Transmission ◽  
Natural Populations ◽  
Oral Route ◽  
Pea Aphid ◽  
Diagnostic Pcr ◽  
Modes Of Transmission

ABSTRACT Quantitative data on modes of transmission are a crucial element in understanding the ecology of microorganisms associated with animals. We investigated the transmission patterns of a γ-proteobacterium informally known as pea aphid Bemisia-like symbiont (PABS), also known as T-type, which is widely but not universally distributed in natural populations of the pea aphid, Acyrthosiphon pisum. The vertical transmission of PABS to asexual and sexual morphs and sexually produced eggs was demonstrated by a diagnostic PCR-based assay, and the maximum estimated failure rate was 2%. Aphids naturally lacking PABS acquired PABS bacteria administered via the diet, and the infection persisted by vertical transmission for at least three aphid generations. PABS was also detected in two of five aphid honeydew samples tested and in all five siphuncular fluid samples tested but in none of 15 samples of salivary secretions from PABS-positive aphids. However, PABS-negative aphids did not acquire PABS when they were cocultured with PABS-positive aphids; the maximal estimated level of horizontal transmission was 18%. A deterministic model indicated that the force of infection by a horizontal transmission rate of 3% is sufficient to maintain a previously described estimate of the prevalence of PABS-positive aphids (37%), if the vertical transmission rate is 98%. We concluded that PABS infections in A. pisum can be maintained by high vertical transmission rates and occasional horizontal transmission, possibly via the oral route, in the absence of selection either for or against aphids bearing this bacterium.

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