Well, maybe not as much is this author claims (“Indeed, polyploidy is a major evolutionary force that can lead to adaptation, speciation, and diversification”), but the story is interesting all the same:
“Genome doubling has shaped the biological world more than any other process,” comments Doug Soltis.
You mean, not Darwinism? Not natural selection? Be careful, you are treading on sacred ground.
“Some might consider this an overstatement, but in the plant world, genome doubling, or polyploidy, rules. It is common in most plant lineages — and it is also crucial in many animal lineages, as vertebrates are the result of two ancient events. It is common in fish, some invertebrate lineages, and we humans are ancient polyploids!”
So, even if polyploidy (duplicate sets of genomes) is the norm rather than unusual, what makes that interesting? One reason is that genome doubling can lead to instant speciation.
As Soltis explains, “If two plants with 12 chromosomes hybridized, you would expect the offspring to have 12 chromosomes, right? What if the offspring had 24 chromosomes? That is genome doubling — every chromosome, every gene duplicated — wow, 2X the genetic material to work with instantaneously!”
In their review, Soltis and colleagues emphasize that polyploidy and the important role it has played, especially in plant evolution, would not have gained the recognition it deserves would it not have been for its staunch proponent, G. L. Stebbins. In the mid-20th century Stebbins synthesized what was known at that time about polyploidy, classifying different types of ploidy, discussing ancient polyploidy events, and investigating hybridizing species and polyploid derivatives. More.
Here’s the abstract:
Polyploidy has long been considered a major force in plant evolution. G. Ledyard Stebbins, Jr., an architect of the Modern Synthesis, elegantly addressed a broad range of topics, from genes to chromosomes to deep phylogeny, but some of his most lasting insights came in the study of polyploidy. Here, we review the immense impact of his work on polyploidy over more than 60 years, from his entrance into this fledgling field in the 1920s until the end of his career. Stebbins and his contemporaries developed a model of polyploid evolution that persisted for nearly half a century. As new perspectives emerged in the 1980s and new genetic tools for addressing key aspects of polyploidy have become available, a new paradigm of polyploidy has replaced much of the Stebbinsian framework. We review that paradigm shift and emphasize those areas in which the ideas of Stebbins continue to propel the field forward, as well as those areas in which the field was held back; we also note new directions that plant geneticists and evolutionists are now exploring in polyploidy research. Perhaps the most important conclusion from recent and ongoing studies of polyploidy is that, following Levin and others, polyploidy may propel a population into a new adaptive sphere given the myriad changes that accompany genome doubling.
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