Identifying genomic hotspots of differentiation and candidate genes involved in the adaptive divergence of pea aphid host races

2018 ◽  
Vol 27 (16) ◽  
pp. 3287-3300 ◽  
Author(s):  
Pierre Nouhaud ◽  
Mathieu Gautier ◽  
Anaïs Gouin ◽  
Julie Jaquiéry ◽  
Jean Peccoud ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Pea Aphid ◽  
Adaptive Divergence ◽  
Host Races ◽  
Aphid Host

scholarly journals Low Spontaneous Mutation Rate and Pleistocene Radiation of Pea Aphids

2020 ◽  
Vol 37 (7) ◽  
pp. 2045-2051
Author(s):  
Varvara Fazalova ◽  
Bruno Nevado
Keyword(s):  
Mutation Rate ◽  
Spontaneous Mutation ◽  
Pea Aphid ◽  
Spontaneous Mutation Rate ◽  
Host Races ◽  
Climatic Oscillations ◽  
Genome Wide ◽  
A Genome ◽  
Pea Aphids ◽  
Aphid Host

Abstract Accurate estimates of divergence times are essential to understand the evolutionary history of species. It allows linking evolutionary histories of the diverging lineages with past geological, climatic, and other changes in environment and shed light on the processes involved in speciation. The pea aphid radiation includes multiple host races adapted to different legume host plants. It is thought that diversification in this system occurred very recently, over the past 8,000–16,000 years. This young age estimate was used to link diversification in pea aphids to the onset of human agriculture, and led to the establishment of the pea aphid radiation as a model system in the study of speciation with gene flow. Here, we re-examine the age of the pea aphid radiation, by combining a mutation accumulation experiment with a genome-wide estimate of divergence between distantly related pea aphid host races. We estimate the spontaneous mutation rate for pea aphids as 2.7×10-10 per haploid genome per parthenogenic generation. Using this estimate of mutation rate and the genome-wide genetic differentiation observed between pea aphid host races, we show that the pea aphid radiation is much more ancient than assumed previously, predating Neolithic agriculture by several hundreds of thousands of years. Our results rule out human agriculture as the driver of diversification of the pea aphid radiation, and call for re-assessment of the role of allopatric isolation during Pleistocene climatic oscillations in divergence of the pea aphid complex.

scholarly journals Intrinsic pre-zygotic reproductive isolation of distantly related pea aphid host races

2018 ◽  
Vol 14 (11) ◽  
pp. 20180332 ◽  
Author(s):  
Varvara Fazalova ◽  
Bruno Nevado ◽  
Ailsa McLean ◽  
H. Charles J. Godfray
Keyword(s):  
Reproductive Isolation ◽  
Host Plant ◽  
Broad Bean ◽  
Mating Behaviour ◽  
Habitat Choice ◽  
Pea Aphid ◽  
Drastic Reduction ◽  
Host Races ◽  
Female Survival ◽  
Aphid Host

Human activities may weaken or destroy reproductive isolation between young taxa, leading to their fusion with consequences for population and community ecology. Pea aphid host races are adapted to different legume taxa, providing a degree of pre-mating isolation mediated by habitat choice. Yet, all races can feed and reproduce on the broad bean ( Vicia faba ), a major crop which represents a ‘universal host plant’, which can promote hybridization between races. Here, we ask if pea aphid host races have reproductive barriers which prevent or reduce gene flow when they co-occur on the universal host plant. We observed mating behaviour, female survival, number of eggs and egg fertilization rates for three types of crosses: among individuals of the same host race, between closely related host races and between distantly related host races. We did not find significant differences in mating behaviour and female survival among the three types of crosses. However, we observed a drastic reduction in the number of eggs laid, and in the number of fertilized eggs, in distant crosses. We conclude that widespread broad bean cultivation in agriculture may predispose closely related—but not distantly related—host races to hybridize, disrupting reproductive isolation between incipient species.

scholarly journals Low spontaneous mutation rate and Pleistocene radiation of pea aphids

2019 ◽  
Author(s):  
Varvara Fazalova ◽  
Bruno Nevado
Keyword(s):  
Mutation Rate ◽  
Spontaneous Mutation ◽  
Pea Aphid ◽  
Spontaneous Mutation Rate ◽  
Host Races ◽  
Climatic Oscillations ◽  
Genome Wide ◽  
A Genome ◽  
Pea Aphids ◽  
Aphid Host

AbstractAccurate estimates of divergence times are essential to understand the evolutionary history of species. It allows linking evolutionary histories of the diverging lineages with past geological, climatic and other changes in environment and shed light on the processes involved in speciation. The pea aphid radiation includes multiple host races adapted to different legume host plants. It is thought that diversification in this system occurred very recently, over the past 8,000 to 16,000 years. This young age estimate was used to link diversification in pea aphids to the onset of human agriculture, and lead to the establishment of the pea aphid radiation as a model system in the study of speciation with gene flow. Here, we re-examine the age of the pea aphid radiation, by combining a mutation accumulation experiment with a genome-wide estimate of divergence between distantly related pea aphid host races. We estimate the spontaneous mutation rate for pea aphids as 2.27 × 10−10 per haploid genome per parthenogenic generation. Using this estimate of mutation rate and the genome-wide genetic differentiation observed between pea aphid host races, we show that the pea aphid radiation is much more ancient than assumed previously, predating Neolithic agriculture by several hundreds of thousands of years. Our results rule out human agriculture as the driver of diversification of the pea aphid radiation, and call for re-assessment of the role of allopatric isolation during Pleistocene climatic oscillations in divergence of the pea aphid complex.

scholarly journals Pea aphid biotype performance on diverse Medicago host genotypes indicates highly specific virulence and resistance functions

2014 ◽  
Vol 104 (6) ◽  
pp. 689-701 ◽  
Author(s):  
S. Kanvil ◽  
G. Powell ◽  
C. Turnbull
Keyword(s):  
Pea Aphid ◽  
Gene Interactions ◽  
Specific Gene ◽  
Plant Interactions ◽  
Host Genotype ◽  
Enhanced Resistance ◽  
Aphid Host ◽  
Highly Virulent ◽  
Specific Virulence ◽  
Aphid Clones

AbstractAphid–plant interactions depend on genotypes of both organisms, which determine the two-way molecular exchange that leads to compatible or incompatible outcomes. The underlying genes are mostly unknown, making it difficult to predict likelihood of aphid success or host resistance, and hampering crop genetic improvement. Here we screened eight pea aphid clonal genotypes collected from diverse legume hosts, on a species-wide panel of Medicago truncatula (Mt) genotypes. Aphid virulence was measured by survival, fecundity and growth rate, together with scores for chlorosis and necrosis as host response indicators. Outcomes were highly dependent on the specific aphid–host genotype combinations. Only one Mt line was fully resistant against all clones. Aphid-induced host chlorosis and necrosis varied greatly, but correlated with resistance only in a few combinations. Bi-clustering analysis indicated that all aphid clones could be distinguished by their performance profiles across the host genotypes tested, with each clone being genetically differentiated and potentially representing a distinct biotype. Clones originating from Medicago sativa ranged from highly virulent to almost completely avirulent on both Medicago species, indicating that some were well adapted, whereas others were most likely migrants. Comparisons of closely related pairs of Australian Mt genotypes differing in aphid resistance revealed no enhanced resistance to European pea aphid clones. Based on the extensive variation in pea aphid adaptation even on unfamiliar hosts, most likely reflecting multiple biotype-specific gene-for-gene interactions, we conclude that robust defences require an arsenal of appropriate resistance genes.

scholarly journals Dynamics of Copy Number Variation in Host Races of the Pea Aphid

2014 ◽  
Vol 32 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Ludovic Duvaux ◽  
Quentin Geissmann ◽  
Karim Gharbi ◽  
Jing-Jiang Zhou ◽  
Julia Ferrari ◽  
...  
Keyword(s):  
Copy Number Variation ◽  
Copy Number ◽  
Pea Aphid ◽  
Host Races ◽  
Number Variation

scholarly journals Differences in Brain Transcriptomes of Closely Related Baikal Coregonid Species

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Oksana S. Bychenko ◽  
Lyubov V. Sukhanova ◽  
Tatyana L. Azhikina ◽  
Timofey A. Skvortsov ◽  
Tuyana V. Belomestnykh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Candidate Genes ◽  
Genetic Factors ◽  
Common Ancestor ◽  
Cell Metabolism ◽  
Adaptive Divergence ◽  
Closely Related Species ◽  
Immune Systems ◽  
Cdna Sequences ◽  
Insight Into

The aim of this work was to get deeper insight into genetic factors involved in the adaptive divergence of closely related species, specifically two representatives of Baikal coregonids—Baikal whitefish (Coregonus baicalensisDybowski) and Baikal omul (Coregonus migratoriusGeorgi)—that diverged from a common ancestor as recently as 10–20 thousand years ago. Using the Serial Analysis of Gene Expression method, we obtained libraries of short representative cDNA sequences (tags) from the brains of Baikal whitefish and omul. A comparative analysis of the libraries revealed quantitative differences among ~4% tags of the fishes under study. Based on the similarity of these tags with cDNA of known organisms, we identified candidate genes taking part in adaptive divergence. The most important candidate genes related to the adaptation of Baikal whitefish and Baikal omul, identified in this work, belong to the genes of cell metabolism, nervous and immune systems, protein synthesis, and regulatory genes as well as to DTSsa4 Tc1-like transposons which are widespread among fishes.

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