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Hybridization—long considered a “dead end”—may be key to rapid speciation


Some researchers pursued the idea, researching a transcontinental fly pest of apples:

Many genetic variants tied to the reproductive isolation of species are older than the species themselves. These old variants are often injected into lineages through hybridization with distant relatives.

A recent review in Trends in Ecology & Evolution argues that this phenomenon reveals something fundamental about how new species form. Old variants recast in new roles may sometimes be more important role in the origin of species than new mutations are. And hybridization — long considered an evolutionary dead end — instead acts as a catalyst for combining old gene variants in new ways, fueling rapid diversification.

The evolutionary biologists David Marques and Ole Seehausen at the University of Bern and Joana Meier at the University of Cambridge call this new view of the origin of species combinatorial speciation.

Jonathan Lambert, “New Hybrid Species Remix Old Genes Creatively” at Quanta

Paper. (open access)

Surely, it was long considered a dead end because Darwinism was supposed to account for these changes.

See also: Hybridization boosts evolution in cichlids


Another dismissed form of evolution shows at least some viability
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From the Quota article:
The list of species groups with similar patterns goes on — Darwin’s finches, the apple maggot fly, capuchino seedeaters, Hawaiian silverswords. The scientists who work on these systems have long recognized the potential importance of hybridization in their radiations. But Marques and his colleagues suggest that the accumulated genomic evidence warrants the introduction of “combinatorial speciation” as a new term to frame future research. The word “combinatorial,” Marques said, seemed to best describe the crucial “generation of new combinations from existing variation, which is really the commonality.” With language that better cuts to the essence of how the speciation is happening, he thinks, researchers will be better equipped to assess the importance of contributions from various mechanisms, including mutations, across the tree of life. “I think it’s a helpful way of reframing a lot of varied, but related, mechanisms under a catchall term,” said Nora Mitchell, a plant biologist who studies hybridization at the University of Wisconsin, Eau Claire. She says she’d like to see introductory biology move away from describing the evolution of biodiversity as relying solely on the origination of new mutations, and toward a more accurate view that encompasses how existing variation can be co-opted.
Many years back, I speculated that if "front-loading" truly occurs, then speciation would likely occur via changes to this "front-loaded" information as the genome became mixed together in subsequent generations. "Combinatorial speciation" seems to capture that thought. Another day; another bad day for Darwinism!! That is: what this "view" suggests is that we're dealing MOSTLY with recombination of existing information, with some slight assistance from mutations. Those mutations may likely take the form of Behe's First Rule of Adaptation--you break the existing information structure slightly. Thus, the theory might look like this: (1) Information is "front-loaded" by an inteligent agent (major phyla); (2) the genetic mechanisms of reproduction move various parts of this information around so as to form new lineages (semi-major phyla); and then (3) mutations within these new genetic rearrangements, of a slightly deleterious nature, so as to adapt to an individual environment (speciation at the lowest phylatic level). Per Darwin, (1) is produced by (3) and (2); what we actually see is (3) produced by (1) and (2). Another bad day for Darwin. PaV
Does this really matter much? Does hybridization or the new term "combinatorial speciation" really solve the problem for Darwinistic processes of the great sparseness, the great distance apart, of peaks of new functional genetic information in the fitness landscape? The problem Michael Behe highlighted in his work on the development of antibiotic resistance with malaria. And more fundamentally, the problem he detailed in Darwin Devolves. doubter
Latemarch, Good questions. OLV
If two species can mate and form a hybrid....were they ever two different species? And why would anyone think that the hybrid is a different species? Latemarch

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