Ptolemy had a big ambition. He wanted to make sense of the motion of stars and planets, so he published a magisterial book. Ptolemy created a mathematical model of the universe that recapitulates the movements of the stars and planets.
There was a fatal flaw at the center of his scheme. Ptolemy believed in the idea that the Earth was the center of the universe. The conclusions of the Ptolemaic universe have been in the history books for over 1200 years.
The field of evolutionary biology is often subject to misguided theoretical approaches that fail to convey the true workings of nature as it shapes the vast array of living forms on Earth.
A new study looks at mathematical models that can be used to understand how evolution works. The study concluded that models should be constructed with the greatest care, avoiding unwarranted initial assumptions, weighing the quality of existing knowledge and remaining open to alternate explanations.
Failure to apply strict procedures in null model construction can lead to theories that seem to square with certain aspects of available data, yet fail to properly explain underlying evolutionary processes.
Compelling but flawed pictures of how evolution acts on populations over time may be offered by such frameworks.
Jeffrey Jensen, a researcher in the Biodesign Center for Mechanisms of Evolution at Arizona State University, leads a group of international experts in providing guidance for future research. They describe a range of criteria that can be used to better ensure the accuracy of models that produce statistical inferences.
Jensen said that one of the key messages was the importance of considering the contributions of evolutionary processes certain to be in constant operation before relying on hypothesized or rare evolutionary processes as the primary drivers of observed population variation.
There are findings in the current issue of the journal.
The field is old.
Early attempts to reconcile Charles Darwin's idea of evolution by means of natural selection with the first inklings of the mechanisms of inheritance were uncovered.
Fisher, Haldane and Wright were the first to explore how natural selection together with other evolutionary forces would modify the genetic composition of Mendelian populations.
Various factors, including natural selection and genetic drift, can affect the genetic composition of a population.
Population geneticists use this theory to design statistical inference approaches for estimating the forces that produce observed patterns of genetic variation in actual populations, and to test their conclusions against accumulated data.
It's the best part of life.
The study of variation in the genomes of people. Some of the variant are important for biological function, while others have no effect on the body.
Variations in the human genome can be a variety of things. One of the most common sources of variation is a single nucleotide polymorphism. It is possible to alter hundreds or even thousands of base pairs simultaneously in the genomes. Many alterations have no effect on disease risk and survival.
Natural selection can happen when a population has different fitness differentials. Population geneticists want to understand the contributing evolutionary processes in a rigorous, quantitative way by studying mathematical models governing the corresponding genes. Population genetics is considered to be the main theory of modern Darwinian evolution.
There is adrift through the genome.
The role of positive selection in increasing the frequencies of beneficial variants is likely to be rare compared to other forms of natural selection. Purging selection is a constantly acting and pervasive form of selection.
There are many non-selective evolutionary processes important. Genetic drift describes the variability inherent to evolution. Natural selection may act more efficiently in large populations than it does in smaller ones.
The difference between prokaryotic organisms and organisms composed of cells is dramatic. The larger the population, the more efficient selection will be. A weaker selection pressure in the eukaryotes is more tolerant of genomic changes if they are not strongly deleterious.
Most evolutionary changes in real populations are governed not by natural selection but by genetic drift according to the Neutral Theory ofMolecular Evolution. Evolutionary biologists often miss this critical point. Natural selection is just one of several evolutionary mechanisms and the failure to realize this is probably the most significant impediment to a fruitful integration of evolutionary theory.
A failure to consider these alternative evolutionary mechanisms, including genetic drift, is likely to lead researchers astray according to the new consensus study. The authors claim that the common over reliance on purely adaptive models has led to a raft of interpretations of dubious value.
A detailed flow chart can be used to guide the development of more accurate models for drawing evolutionary inferences. The way the genome is structured and life history are two of the parameters that vary among species. All of these factors are important in controlling observed variation and evolution.
Many excellent research groups atASU and around the world are actively improving our understanding of these underlying evolutionary parameters, providing constantly improving inference.
The field of population genetics has changed dramatically because of the availability of low-cost, high-quality data. The use of this gold mine of data will help advance the most rigorous models to uncover evolution's many remaining mysteries.
More information: Parul Johri et al, Recommendations for improving statistical inference in population genomics, PLOS Biology (2022). DOI: 10.1371/journal.pbio.3001669 Journal information: PLoS Biology
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