Drivers of evolutionary change: understanding stasis and non-stasis through integration of micro- and macroevolution

Microevolution, changes in the genetic composition of populations, may over time lead to the formation of new species, macroevolution. Through "The Modern Synthesis" in the 1930s and 40s, Darwin's theory of evolution through natural selection was combined with Mendel's laws of inheritance. It was shown how macroevolution could potentially follow from microevolution, and mathematical models explaining the evolutionary changes observed on short time scales were developed. A remaining problem is that these models do not adequately explain macro-evolutionary data. While one at the microevolutionary scale studies genetic changes in living organisms, one often relies on fossil data at the macroevolutionary level. One phenomenon observed in the fossil data is that some forms seem to remain unchanged over millions of years. This is called stasis and constitutes a great paradox considering the rapid evolutionary changes observed on a short time scale. A key question is whether evolution will stop - resulting in stasis - if abiotic factors (such as climate) are kept constant. Recently, researchers at CEES published a study showing that this is not necessarily the case. Biotic factors, that is, the influence of other competing individuals, exert great influence on an organism. Evolutionary changes within a species affect the living environment of all coexisting individuals, in the same or other species. This is the basis for the Red Queen hypothesis where species must adapt at all times to avoid extinction. This project will use knowledge from both evolution and ecology to develop new mathematical models to unify our understanding of both microevolution and macroevolution. Furthermore, the project will investigate whether stasis / non-stasis can be explained by using microevolutionary-derived processes on macroevolutionary data. Since project startup, a kick-off meeting has been held where the researchers on the project gathered with collaborators from Oslo, Bergen and Helsinki. The researchers employed on the project have been co-located to collaborate on a daily basis to develop models to unite microevolution and macroevolution. One of the researchers has been on a four-week research stay at the University of Helsinki to work with collaborators there on the use of fossil material in empirical studies of biodiversity dynamics. One researcher has left the project for a permanent job and have been replaced by a new project member during the reporting period. One researcher has been in parental leave (17 weeks, February-July 2020) during the reporting period, and will consequently have his contract prolonged until December 31, 2020. We have had several working meetings, both in Oslo and in Helsinki, two papers have been published in peer-reviewed journals, one paper have been published in a popular science magazine, and several manuscripts are currently in preparation. Several lectures based on the project have been given.

As has been mentioned in the report, we have a proposal under consideration in the British Leverhulme Foundation (Stenseth being co-PI: asking for funding for one post doc over two years). In addition, as mentioned above, we will apply for a HFSP – as Norway became a member of HFSP again – for a follow-up; co-applicants will be chosen among those attending the Tømte-symposium. Nordbotten and Stenseth will in 2024 furthermore apply for FRIPRO-funding for a follow-up: we did have one in 2021 which was not funded but got reasonably good reviews – with more publications out we will, one might assume, be able to submit a much strengthened proposal.

The project will investigate whether - and how - macro-evolution can be fully understood as a result of micro-evolutionary processes. This will be achieved by integrating micro-evolutionary theory with theories on macro-evolution, hence determining whether we can explain macro-evolution within the framework of the Modern Synthesis or need to go beyond it. For answering these fundamental questions we have assembled an international and multidisciplinary team of researchers that includes world leading scientists in their relevant fields. Given the track-record, background and expertise that the team brings together, we expect cutting-edge results with broad implications within the field of evolutionary biology. The disconnect between micro- and macro-evolution is in part due to a surprisingly persistent disconnect between ecological and evolutionary research. In order to understand the whole picture we need to bring ecological and evolutionary dynamics together into a common model-framework where not only their relative weight but, we believe more importantly, their dynamic interactions including feedback loops can be investigated. For this purpose we need causality modelling/analysis, a key component of our proposed project. The project achieves focus and feasibility by investigating in depth the phenomenon of stasis vs. non-stasis of evolution. By assessing to what degree micro-evolutionary processes can explain this observed macro-evolutionary pattern we also assess to what degree we need a separate theory for macro-evolution. The crucial novelty that makes the proposed project operational is the integration of mathematical modelling with state-of-the-art analysis of fossil mammal data as well as experimental microbiological data.