Format

Send to

Choose Destination
PLoS One. 2015 Jul 15;10(7):e0132184. doi: 10.1371/journal.pone.0132184. eCollection 2015.

Tandem Duplications and the Limits of Natural Selection in Drosophila yakuba and Drosophila simulans.

Author information

1
Ecology and Evolutionary Biology, University of California, Berkeley, California, United States of America.
2
Ecology and Evolutionary Biology, University of California, Davis, Davis, California, United States of America.
3
Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, United States of America.
4
Ecology and Evolutionary Biology and the Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America.

Abstract

Tandem duplications are an essential source of genetic novelty, and their variation in natural populations is expected to influence adaptive walks. Here, we describe evolutionary impacts of recently-derived, segregating tandem duplications in Drosophila yakuba and Drosophila simulans. We observe an excess of duplicated genes involved in defense against pathogens, insecticide resistance, chorion development, cuticular peptides, and lipases or endopeptidases associated with the accessory glands across both species. The observed agreement is greater than expectations on chance alone, suggesting large amounts of convergence across functional categories. We document evidence of widespread selection on the D. simulans X, suggesting adaptation through duplication is common on the X. Despite the evidence for positive selection, duplicates display an excess of low frequency variants consistent with largely detrimental impacts, limiting the variation that can effectively facilitate adaptation. Standing variation for tandem duplications spans less than 25% of the genome in D. yakuba and D. simulans, indicating that evolution will be strictly limited by mutation, even in organisms with large population sizes. Effective whole gene duplication rates are low at 1.17 × 10-9 per gene per generation in D. yakuba and 6.03 × 10-10 per gene per generation in D. simulans, suggesting long wait times for new mutations on the order of thousands of years for the establishment of sweeps. Hence, in cases where adaptation depends on individual tandem duplications, evolution will be severely limited by mutation. We observe low levels of parallel recruitment of the same duplicated gene in different species, suggesting that the span of standing variation will define evolutionary outcomes in spite of convergence across gene ontologies consistent with rapidly evolving phenotypes.

PMID:
26176952
PMCID:
PMC4503668
DOI:
10.1371/journal.pone.0132184
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center