Candidate genes for host association in aphids

Lead Research Organisation: University of Sheffield
Department Name: Animal and Plant Sciences


The origin of new biological species depends on the evolution of characters that prevent them from mating and producing successful offspring. This evolutionary process may start with adaptation to new environments but this rarely creates a complete reproductive barrier. If some interbreeding occurs, then genes which are not directly involved in adaptation to different habitats can still be shared. We still have little understanding of how evolution proceeds from this point to the point of complete prevention of interbreeding.
In this project, we propose to study the pea aphid because its genome has been sequenced and it is known to feed on several different host plant, which represent distinct environments. We know that aphids tend to reproduce with others that use the same plant. This tendency is stronger in some cases than others so we have several points on the progression towards new species that we can compare.
Aphids use chemical cues to choose the plant on which they feed and we now know the types of genes underlying recognition of these cues. We have already found some of these genes that are likely to be involved in the differences in behaviour between aphids that use different plants. In this new project we want to find out how these genes are influenced by natural selection and how they affect the sharing of other genes between host races of aphids. We also want to find out which chemicals in the plants are used in the recognition process.
This will help us to understand the origin of species and it may also help in control of aphids that are pests of crops. Understanding how aphids choose the plants they want to feed on can provide new tools to prevent aphid damage.

Planned Impact

Who will benefit from this research?

In addition to academic beneficiaries, we identify two interested groups:

1. Agriculturalists and horticulturists - many aphid species are agricultural or horticultural pests. Most are host specialists. Understanding how aphids discriminate host plants from non-host plants holds great interest in these sectors.
2. The public - evolution is of great public interest, and is often a controversial topic. The origin of species is of particular interest, partly because of the title of Darwin's book and partly because some groups find modification within species easier to accept than the origin of new species. Speciation is a slow process and therefore difficult to demonstrate in a satisfactory way. Cases like the pea aphid, where mutliple different stages in the process of divergence are available, are good vehicles for education about speciation.

How will they benefit from the research?

1. We do not expect directly exploitable results from this project but it may indicate new strategies for aphid control. We will ensure that relevant results are communicated to potential beneficiaries through appropriate publications, attendance at meetings and direct contacts with companies.
2. Public understanding of evolution contributes to the quality of life, particularly in modern society where evolution is relevant to many societal problems ranging from antibiotic resistance to management of fish stocks. We will communicate our results to the public through appropriate publications and other means of dissemination.
Description We have identified a subset of the genes responsible for chemical recognition in aphids that are critical for the evolution of new host-plant associations.
Exploitation Route In the medium to long term, our findings may be of use in the control of aphid pests on crops
Sectors Agriculture

Food and Drink

Title Data from: Differential gene expression according to race and host plant in the pea aphid 
Description Host-race formation in phytophagous insects is thought to provide the opportunity for local adaptation and subsequent ecological speciation. Studying gene expression differences amongst host races may help to identify phenotypes under (or resulting from) divergent selection and their genetic, molecular and physiological bases. The pea aphid (Acyrthosiphon pisum) comprises host races specializing on numerous plants in the Fabaceae and provides a unique system for examining the early stages of diversification along a gradient of genetic and associated adaptive divergence. In this study, we examine transcriptome-wide gene expression both in response to environment and across pea aphid races selected to cover the range of genetic divergence reported in this species complex. We identify changes in expression in response to host plant, indicating the importance of gene expression in aphid-plant interactions. Races can be distinguished on the basis of gene expression, and higher numbers of differentially expressed genes are apparent between more divergent races; these expression differences between host races may result from genetic drift and reproductive isolation and possibly divergent selection. Expression differences related to plant adaptation include a subset of chemosensory and salivary genes. Genes showing expression changes in response to host plant do not make up a large portion of between-race expression differences, providing confirmation of previous studies' findings that genes involved in expression differences between diverging populations or species are not necessarily those showing initial plasticity in the face of environmental change. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Description SPECIAPHID 
Organisation French National Institute of Agricultural Research
Department INRA Rennes Centre
Country France 
Sector Public 
PI Contribution Materials and data sharing.
Collaborator Contribution Materials and data sharing.
Impact Duvaux et al 2015.
Start Year 2013