Periodic Reporting for period 1 - MutANTs (Mutation rate evolution in attine ants)
Periodo di rendicontazione: 2020-09-01 al 2022-08-31
Germline mutations (GMs, heritable DNA alterations in germ cells) are the driving force behind evolution, so the rate at which these changes in ‘genetic blueprints’ arise (germline mutation rate, GMR) is a fundamental question relevant for all biology. GMR varies across species. On one hand, GMs are the primary source of genetic diversity, because they create new variation in the gene pool and increase the potential for novel phenotypic traits that natural selection can work on; this implies that a non-zero GMR is essential for the survival of populations in a perpetually changing environment. On the other hand, because most mutations are deleterious, GMR is most likely to cause genome instability and decreased fitness if not sterility or lethality, so that GMR is likely to be under balancing selection with responses to selection depending on lineage-specific genome architecture and environmental conditions affecting life-history adaptations and population sizes. GMR also varies within species. In particular, GMR is expected to increase with parental age, because the strength of selection on GMR is inevitably relaxed with advancing age and deleterious mutations expressed late in life fail to be purged. Understanding how natural selection may affect evolutionary change in GMR across species and how the strength of selection on GMR changes with parental age is a general question of huge importance and highly relevant for the pressing need to understand disease vulnerability in aging human populations and problems of genetic load when designing long-term prognoses in conservation biology.
MutANTs proposed to identify the evolutionary forces driving the variation in germline mutation rate within and across species. To achieve this goal, MutANTs had two scientific Objectives (Obs.):
Ob. 1 - To develop the first model of maternal age-dependent germline mutation rate (GMR) using whole-genome re-sequencing data from a 14-year collection of mother-sons samples of the CSE laboratory attine ant species Acromyrmex echinatior; and
Ob. 2 - To develop the first comprehensive understanding of phylogenetically GMR evolution as a function of maximal life-span of queens, mean mature colony size, social system, and Ne - adjusted for phylogenetic ancestry - capturing the key characteristics of comparative attine life-history, based on mother-offspring whole-genome re-sequencing data from 12 attine species and 9 outgroup ant species.
MutANTs proposed to identify the evolutionary forces driving the variation in germline mutation rate within and across species. To achieve this goal, MutANTs had two scientific Objectives (Obs.):
Ob. 1 - To develop the first model of maternal age-dependent germline mutation rate (GMR) using whole-genome re-sequencing data from a 14-year collection of mother-sons samples of the CSE laboratory attine ant species Acromyrmex echinatior; and
Ob. 2 - To develop the first comprehensive understanding of phylogenetically GMR evolution as a function of maximal life-span of queens, mean mature colony size, social system, and Ne - adjusted for phylogenetic ancestry - capturing the key characteristics of comparative attine life-history, based on mother-offspring whole-genome re-sequencing data from 12 attine species and 9 outgroup ant species.
Specifically, two work packages (WP1 and WP2) were designed to achieve Ob. 1, and three work packages (WP3-5) were designed to achieve Ob. 2. For Ob. 1, WP1 included two stages, DNA extraction and sequencing, whereas WP2 included three stages, bioinformatic analysis, statistical analysis, and manuscript writing. For Ob. 2, WP3 included two stages (DNA extraction and sequencing), WP4 included one stage (bioinformatic analysis), and WP5 included two stages (statistical analysis and manuscript writing).
For Ob. 1, total 89 ant specimens from four replicated A. echinatior colonies, with maternal ages spamming from 4 years to 22 years, were DNA extracted and whole-genome re-sequenced. Bioinformatic and statistical analyses indicated that sons produced at younger maternal ages harbor fewer germline mutations than sons produced at older maternal ages. The raw sequence data and the scripts for bioinformatic and statistical analyses could be exploited by peer researchers and will be disseminated immediately upon the publication of the relevant manuscript.
For Ob. 2, mother-sons samples of 17 attine and non-attine species (5 attine species, 12 non-attine species) were DNA extracted and are in the progress of whole-genome re-sequencing. The raw sequence data and the scripts for bioinformatic and statistical analyses could be exploited by peer researchers and will be disseminated immediately upon the publication of the relevant manuscript.
For Ob. 1, total 89 ant specimens from four replicated A. echinatior colonies, with maternal ages spamming from 4 years to 22 years, were DNA extracted and whole-genome re-sequenced. Bioinformatic and statistical analyses indicated that sons produced at younger maternal ages harbor fewer germline mutations than sons produced at older maternal ages. The raw sequence data and the scripts for bioinformatic and statistical analyses could be exploited by peer researchers and will be disseminated immediately upon the publication of the relevant manuscript.
For Ob. 2, mother-sons samples of 17 attine and non-attine species (5 attine species, 12 non-attine species) were DNA extracted and are in the progress of whole-genome re-sequencing. The raw sequence data and the scripts for bioinformatic and statistical analyses could be exploited by peer researchers and will be disseminated immediately upon the publication of the relevant manuscript.
MutANTs’ outcomes will have major interdisciplinary impact on several scientific fields, including: ageing (the results of Ob. 1 will shed general lights on how GMs accumulate with age), ecology (the results of Ob. 2 will provide invaluable information on interactions between genome organization and environmental pressure), as well as phylogenetics (the results of Ob. 2 will further reinforce the accuracy of the attine phylogeny).