It was found that young genes adapt faster than old ones

PLOS Biology (2022). DOI: 10.1371 / journal.pbio.3001775″ width=”800″ height=”378″/>

(a) Phylogenetic definition of the layers used in the analyzes of A. thaliana (top) and D. melanogaster (bottom). The number of genes assigned to each clade is shown. (b) Relationship between rate of protein evolution (ω), non-adaptive and non-synonymous (ωna) substitutions, and adaptive non-synonymous (ωa) substitutions with gene lifespan in A. thaliana (top) and in D. melanogaster (bottom). The cladding is arranged according to (a). In D. melanogaster, results for X-linked genes, epigenetics, and total genes are shown. The mean values ​​of ω, ωna, and a for each category are represented by black dots. Error bars indicate the 95% confidence interval for each category, calculated over 100 bootstrap replicates. attributed to him: Biology Plus (2022). DOI: 10.1371 / journal.pbio.3001775

A new study from the Max Planck Institute for Evolutionary Biology in Plon and the University of Sussex in the UK shows that the age of a gene determines how quickly it adapts. These results show how gene evolution occurs as an ‘adaptive process’ through time.

New species arise and evolve because individuals accumulate mutations in their genome, some of which have no effect. Others lead to changes that give their carriers distinct competitive advantages. As early as 1932, Sewall Wright introduced a metaphor that has inspired decades of theories and Experimental research in evolutionary biology To describe the process of adaptation. Wright described the “fitness scene” model.

Here the evolving population has been described as “itinerant” heading towards peak fitness. Much like a mountaineer climbing slowly to the top of a mountain. In 1998, Orr explained that this “adaptive walking” follows a simple rule of diminishing returns: the further away the population is from their peak fitness, the more steps they take.

One of the predictions of this theory is that it developed recently, i.e. “young people” genes They tend to accumulate more adaptive mutations with greater effects than older genes because they are far from their peak fitness. This is exactly the hypothesis that Anna Phillipa Motineau and Julian Dothel of the Max Planck Institute for Evolutionary Biology, together with Adam Eyre Walker of the University of Sussex, wanted to test.

However, testing this hypothesis has proven to be very difficult. The historical record of accumulated mutations in a gene is usually not available, and their effects on fitness are largely unknown. Furthermore, other characteristics of genes, such as their length, can distort the effect of gene age. Therefore, the authors proposed a novel approach to test the adaptive gait model of gene evolution.

First, they used population genetic models that can assess variability in the fitness effect of mutations. To do this, they compared the genomes of several individuals in a population and measured the rate of adaptive evolution in different gene classes. Likewise, they took advantage of the fact that not all genes in the genome are the same age.

Some genes are small and only a few closely related genes are involved Related species, while others are much older and are shared by species that split millions of years ago. Finally, they used the distribution of mutations between genes of different ages to understand how adaptive mutations spread over time.

using two Distinctive types, the fruit fly Drosophila melanogaster and the small flowering plant Arabidopsis thaliana, this study showed that gene age significantly influences the rate of molecular adaptation and that mutations in small genes tend to have larger effects. These results provide the first strong empirical evidence of this molecular evolution The adaptive walking model follows a deep evolutionary time scale and adds a new layer of evidence to a fitness landscape theory proposed nearly 100 years ago.

The search was published in Biology Plus.

Gene fusion as an important mechanism for generating new genes in Oryza genomes

more information:
Ana Filipa Moutinho et al, Strong evidence for an adaptive gait model of gene evolution in Drosophila and Arabidopsis, Biology Plus (2022). DOI: 10.1371 / journal.pbio.3001775

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