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FRIMEDBIO-Fri prosj.st. med.,helse,biol

Dissecting evolutionary rates across time: Bridging micro- and macroevolution (DETERMINE)

Alternative title: Evolusjon på ulike tidsskalaer: Syntese av mikro- og makroevolusjon.

Awarded: NOK 7.0 mill.

Studies of fossils represent a unique possibility for understanding how past life forms coped with changes in their environment, whether they adapted to the new conditions or failed to survive. It is a common view that many species in the fossil record show little change, often for as long as millions of years. Studies of extant populations on the other hand have shown that most populations have a large potential to evolve. Substantial evolution is also often observed, both in studies of wild populations and during selection experiments in labs. One of the primary objectives of this project is to understand if rates of evolutionary change are truly different across time scales. It is also a goal to identify factors that make certain species exceptional evolvers and understand on which time scales potential constraining mechanisms hinder evolution. A better understanding of which factors that facilitate and constrain evolution may provide clues regarding which species we can expect will be able to cope well with climate change, and which species that will have problems surviving. A large-scale analysis of hundreds of fossil time series showed a surprising result: It has been commonly assumed that species mainly undergo evolutionary change during speciation, and that species remains more or less unchanged after they appear in the fossil record. However, our investigation showed that the pattern of evolution does not predict the amount of evolution that happens in lineages in the fossil record. The paper where these results where presented was highlighted by Nature as an important contribution to the field. A new and larger analysis of several hundred species in the fossil record investigated the hypothesis that morphological stasis (the observation that species undergo only minor changes on long time intervals) is caused by perfect adaptation of species to a non-changing environment. The results of the study do not support this hypothesis: The species that were studied showed larger fluctuations in their morphology than expected given a hyper stable environments, which suggests that other explanations need to be assessed to explain long-term stasis in the fossil record. This study support the hypothesis that morphological stasis in the fossil record contains more evolutionary change than what has previously been assumed and advocated. It is known that ecological interactions between species lead to selection and subsequent evolution, which again leads to changes in the species ecology. But is it possible to study long-term effects of ecological changes in the fossil record? A new study from the project suggests it is possible. The study presents a new model of evolution portraying expected evolution in a population when it enters a new habitat. This model - together with other models of evolution - were fitted to data from the fossil record. The results show that the new ?ecological? model of evolution best explains some of the data from the fossil record. The study exemplifies how it is possible to study and test predictions from ecological and evolutionary theory in the fossil record. The study also shows how some species evolve fast in new environments and that the rate of evolution slows down as a function of time in the new environment. Is speciation generally a 'special time' in evolution, or are lineage-splitting events (speciation evets) just ?more of the same? where the end product happens to be two separate lineages? The fossil record of the bryozoan genus Metrarabdotos is considered a text-book example of a clade where speciation causes rapid evolutionary change against a backdrop of morphological stasis within lineages. In a new study, we point to some methodological and measurement theoretical issues in the original work on Metrarabdotos. In our reanalysis of the original data, we consistently fail to find variation in the evolutionary process during within-lineage evolution compared with speciation events. Although widely considered the best example of a punctuated mode of evolution, morphological divergence and speciation are not linked in Metrarabdotos. Two studies in the project are about to be finished. Both studies investigate whether there is any predictive power in the variation within a population on the amount of evolution that will happen in the future. This is difficult to investigate using living taxa only, so both studies use data from the fossil record. One study use bryozoans as a model system while the second study uses a large dataset that contain all sorts of taxa from the fossil record with information on the variation in phenotrypic traits. Interestingly, we often find a relationship between the variability of populations and how much evolution that happens in the future.

Prosjektet har resultert i en rekke artikler i velrennomerte journaler. Noen av artiklene har også vakt oppsikt blant internasjonale kollegaer. Erfaringer med og resultatene fra prosjektet har vært svært avgjørende for at PI vant fram i konkurransen om en ERC starting grant i 2020. Arthur Porto har skaffet seg en fast stilling ved Louisiana State University kort tid etter sin postdoktor-stilling på prosjektet. Flere av studiene fra prosjektet har analysert fossile data på nye måter og ofte kommet til motsatte konklusjoner enn rådende konsensus. Vi håper at noen av disse resultatene kan, på sikt, føre til en økt debatt om hvor mye og hva slags type evolusjon som er mulig å observere i fossile data. Prosjektet har også utviklet nye statistiske metoder og programvare for å analysere fossile data. Vi tror og håper prosjektet har åpnet øynene hos en del kollegaer innen fagfeltet for hvilke muligheter som åpner seg ved å benytte seg av disse metodiske og teknologiske nyvinningene.

Species are currently experiencing environmental changes due to anthropogenic influence, changes that will continue for unknown time spans. Fossils are the only data we have to understand how earlier life forms have coped with previous changes in their environment. Given this backdrop, there is something deeply disconcerting about the current state of knowledge on how we understand the evolutionary potential of species over different time scales. A dominating view of the fossil record is that species remain very similar during their existence, with changes mainly happening during speciation events. This pattern contrasts with the enormous potential for evolution observed on shorter time scales. In short, why do we observe so little evolutionary change in the fossil record when we have been able to produce substantial evolutionary change over only a few generations in the lab? The DETERMINE project will use a combination of conceptually novel approaches together with more established methodology to investigate whether the evolutionary potential of species is actually different across time. Part of the project involves analyzing hundreds of ancestor-descendent time series. This will allow us to understand if evolution is truly different across time scales. The same data will also enable us to identify species that are exceptional evolvers. These taxa will be used as case studies for understanding if fast evolvers share certain characteristics that enable them to evolve more quickly compared to other species. A new model system of fossils will also be studied to better understand how different constraints on the evolutionary process breaks down over time. Results from the DETEMINE project will reduce the divide between our understanding of evolution on short (microevolution) and long timescales (macroevolution), and will enable better predictions on how species can be expected to cope with the ongoing global environmental changes over different time intervals.

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FRIMEDBIO-Fri prosj.st. med.,helse,biol

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