Project Details
Projekt
Towards testable quantitative models for the evolution of caste specific ageing part II: integrating theory and experiment
Applicant
Professor Dr. Ido Pen
Subject Area
Evolution, Anthropology
Term
from 2015 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 261675780
A major challenge for evolutionary theory is to explain how in social insects the reproductive caste has evolved a lifespan much greater than that of the worker caste and that of similar-sized non-social insects. Although verbal arguments from classical evolutionary ageing theories – mutation accumulation (MA), antagonistic pleiotropy (AP), disposable soma (DS) – have been used to qualitatively explain caste-specific ageing, the classical models cannot apply because their assumptions clash with social insect biology. The aims of this project are to (1) develop general and species-specific quantitative models for the evolution of caste-specific ageing, and (2) integrate the models with experimental data from the Research Unit (RU), in order to rigorously test and refine the models and to help guide further experimental research. During the 1st funding phase we achieved several conceptual breakthroughs regarding caste-specific ageing. First, we have shown mathematically that one of the bedrock principles of classical ageing theory – the declining force of natural selection with age – does not apply to the social insect reproductive caste. Instead, selection on queen survival can continue to act at maximal strength long after the age of first reproduction. This can be understood from a “superorganism” viewpoint, with queens acting as de facto “germline”, and the production of workers amounting to “somatic growth” rather than reproduction. Secondly, we have shown that the between-caste divergence in the strength of selection can indeed trigger the evolution of strongly increased queen/worker lifespan ratios, but the question remains what combination of mechanisms (MA and/or SA and/or DS and/or others) is required to explain the quantitatively extreme divergence observed in nature.For the remainder of the 1st phase we intend to further analyse this question, and to start integrating the models with transcriptome data from the other RU projects by mapping age-by-caste correlations in expression levels to trade-offs in the models, which will yield the first quantitative predictions for caste-specific ageing profiles. For the 2nd phase we have two main goals. The first goal is to develop more mechanistic extensions of our current models by (a) incorporating explicitly evolvable genetic regulatory networks underlying the resource allocation processes that cause trade-offs between fitness components, both at the within-caste and between-caste levels; and (b) by allowing the degree of caste specialization and the number of castes to co-evolve with caste-specific ageing phenotypes. The second goal is to further integrate life historical, social and bioinformatics data from other RU projects with the models. This should allow an unprecedented degree of quantitative testing of evolutionary ageing models, which we hope will considerably advance the evolutionary ageing field in general, beyond our applications to social insects.
DFG Programme
Research Units
International Connection
Netherlands
Co-Investigators
Professor Dr. G. Sander van Doorn; Professor Dr. Franz Josef Weissing
