TY - JOUR
T1 - The divergence of mean phenotypes under persistent directional selection
AU - Devi, Archana
AU - Speyer, Gil
AU - Lynch, Michael
N1 - Funding Information:
This research was supported by the Multidisciplinary University Research Initiative awards W911NF-09-1-0444 and W911NF-09-1-0444 from the US Army Research Office, National Institutes of Health award R35-GM122566-01, National Science Foundation awards DBI-2119963, DEB-1927159, and MCB-1518060, and Moore and Simons Foundations Grant 735927.
Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of The Genetics Society of America. All rights reserved.
PY - 2023/7
Y1 - 2023/7
N2 - Numerous organismal traits, particularly at the cellular level, are likely to be under persistent directional selection across phylogenetic lineages. Unless all mutations affecting such traits have large enough effects to be efficiently selected in all species, gradients in mean phenotypes are expected to arise as a consequence of differences in the power of random genetic drift, which varies by approximately five orders of magnitude across the Tree of Life. Prior theoretical work examining the conditions under which such gradients can arise focused on the simple situation in which all genomic sites affecting the trait have identical and constant mutational effects. Here, we extend this theory to incorporate the more biologically realistic situation in which mutational effects on a trait differ among nucleotide sites. Pursuit of such modifications leads to the development of semi-analytic expressions for the ways in which selective interference arises via linkage effects in single-effects models, which then extend to more complex scenarios. The theory developed clarifies the conditions under which mutations of different selective effects mutually interfere with each others' fixation and shows how variance in effects among sites can substantially modify and extend the expected scaling relationships between mean phenotypes and effective population sizes.
AB - Numerous organismal traits, particularly at the cellular level, are likely to be under persistent directional selection across phylogenetic lineages. Unless all mutations affecting such traits have large enough effects to be efficiently selected in all species, gradients in mean phenotypes are expected to arise as a consequence of differences in the power of random genetic drift, which varies by approximately five orders of magnitude across the Tree of Life. Prior theoretical work examining the conditions under which such gradients can arise focused on the simple situation in which all genomic sites affecting the trait have identical and constant mutational effects. Here, we extend this theory to incorporate the more biologically realistic situation in which mutational effects on a trait differ among nucleotide sites. Pursuit of such modifications leads to the development of semi-analytic expressions for the ways in which selective interference arises via linkage effects in single-effects models, which then extend to more complex scenarios. The theory developed clarifies the conditions under which mutations of different selective effects mutually interfere with each others' fixation and shows how variance in effects among sites can substantially modify and extend the expected scaling relationships between mean phenotypes and effective population sizes.
KW - evolutionary divergence
KW - mutation bias
KW - phenotypic divergence
KW - phenotypic scaling
KW - random genetic drift
KW - selective interference
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U2 - 10.1093/genetics/iyad091
DO - 10.1093/genetics/iyad091
M3 - Article
C2 - 37200616
AN - SCOPUS:85164260697
SN - 0016-6731
VL - 224
JO - Genetics
JF - Genetics
IS - 3
M1 - iyad091
ER -