Natural selection has driven the recurrent loss of an immunity gene that protects Drosophila against a major natural parasite
Polymorphisms in immunity genes can have large effects on susceptibility to infection. To understand the origins of this variation, we have investigated the genetic basis of resistance to the parasitoid wasp in We found that increased expression of the gene after infection by parasitic wasps was ass...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 120; no. 33; p. e2211019120 |
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Main Authors | , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
15.08.2023
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Subjects | |
Online Access | Get full text |
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Summary: | Polymorphisms in immunity genes can have large effects on susceptibility to infection. To understand the origins of this variation, we have investigated the genetic basis of resistance to the parasitoid wasp
in
We found that increased expression of the gene
after infection by parasitic wasps was associated with a faster cellular immune response and greatly increased rates of killing the parasite.
encodes a protein that is strongly up-regulated in the fat body after infection and localizes to the surface of the parasite egg. In certain susceptible lines, a deletion upstream of the
has largely abolished expression. Other mutations predicted to abolish the function of this gene have arisen recurrently in this gene, with multiple loss-of-expression alleles and premature stop codons segregating in natural populations. The frequency of these alleles varies greatly geographically, and in some southern African populations, natural selection has driven them near to fixation. We conclude that natural selection has favored the repeated loss of an important component of the immune system, suggesting that in some populations, a pleiotropic cost to
expression outweighs the benefits of resistance. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 1R.A., S.O.Z., and J.P.D. contributed equally to this work. Edited by Harmit Malik, Fred Hutchinson Cancer Center, Seattle, WA; received July 3, 2022; accepted June 26, 2023 |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.2211019120 |