Abstract
Evolutionary theories of ageing predict a reduction in selection efficiency with age, a so-called “selection shadow,” due to extrinsic mortality decreasing effective population size with age. Classic symptoms of ageing include a deterioration in transcriptional regulation and protein homeostasis. Understanding how ant queens defy the trade-off between fecundity and lifespan remains a major challenge for the evolutionary theory of ageing. It has often been discussed that the low extrinsic mortality of ant queens, that are generally well protected within the nest by workers and soldiers, should reduce the selection shadow acting on old queens. We tested this by comparing strength of selection acting on genes upregulated in young and old queens of the ant, Cardiocondyla obscurior. In support of a reduced selection shadow, we find old-biased genes to be under strong purifying selection. We also analyzed a gene coexpression network (GCN) with the aim to detect signs of ageing in the form of deteriorating regulation and proteostasis. We find no evidence for ageing. In fact, we detect higher connectivity in old queens indicating increased transcriptional regulation with age. Within the GCN, we discover five highly correlated modules that are upregulated with age. These old-biased modules regulate several antiageing mechanisms such as maintenance of proteostasis, transcriptional regulation, and stress response. We observe stronger purifying selection on central hub genes of these old-biased modules compared with young-biased modules. These results indicate a lack of transcriptional ageing in old C. obscurior queens, possibly facilitated by strong selection at old age and well-regulated antiageing mechanisms.
Original language | English |
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Article number | evab093 |
Number of pages | 13 |
Journal | Genome Biology and Evolution |
Volume | 13 |
Issue number | 6 |
Early online date | 4 May 2021 |
DOIs | |
Publication status | Published - 1 Jun 2021 |
Externally published | Yes |
Bibliographical note
This is an Open Access article distributed under the terms of the CreativeCommons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected]Funder
This article was written as part of the research carried out by the DFG Collaborative Research Unit (RU) “Sociality and the Reversal of the Fecundity-longevity Trade-off” (DFG FOR2281, www.so-long.org), and we thank the members of the RU for stimulating discussions. M.C.H. was supported by a DFG grant BO2544/11-1 to E.B.B. J.O. and L.M.J.N. were supported by DFG grant OE549. M.R. and T.F. were supported by the Swiss National Science Foundation (SNSF) (grants 310030E-164207 and 31003A_182262 to T.F.) and the Novartis Foundation for Medical-Biological Research (grant 19B149 to T.F.).Keywords
- ageing
- selection shadow
- social insects
- longevity/fecundity trade-off.