At Eurekalert, we learn about “The mechanics of speciation: Model examines factors that contribute to the emergence of new species” (24-Jun-2011). And we learn that sympatric speciation – a key current claim – is “not impossible.”
The National Institute for Mathematical and Biological Synthesis (NIMBioS) explains,
Mate choice, competition, and the variety of resources available are the key factors influencing how a species evolves into separate species, according to a new mathematical model that integrates all three factors to reveal the dynamics at play in a process called sympatric speciation.New species more commonly occur when plants or animals cannot interbreed because of strong mate choice, and therefore they become isolated genetically. A less common type of speciation, called “sympatric,” occurs when a new species arises from a single population that has no geographic or physical barriers. A famous example is the Rhagoleitis pomonella fruit fly that originally feasted on the fruit of hawthorn trees, then shifted and began to feed on apples, evolving into a more genetically distinct type of fly.
“More genetically distinct”?
The hawthorn tree (Crateaegus) is a member of the rose family (Rosaceae), as is the apple tree. The difference is that the apple got domesticated for fruit (in a thousand varieties) with a high sugar content, which probably explains why many fruit flies living in orchards gravitated to them and forsook the stingy wild hawthorn. May we assume that “more genetically distinct” does not mean “a new species”?
The new model integrates three key factors that can lead to sympatric speciation: the degree to which male foraging traits influence female mate choice, the degree to which different individuals compete for resources, and the variety of resources available. By incorporating three different factors together, the study’s authors, Xavier Thibert-Plante, a postdoctoral fellow at the National Institute for Mathematical and Biological Synthesis, and Andrew P. Hendry, an associate professor at McGill University, have taken a different more inclusive approach than in previous studies, which examine one or a few primary factors.”This way we can consider the effects of multiple factors and their interactions simultaneously. At the very least, having a variety of resources available in the model is a productive way of generating insights into biological diversity,” Thibert-Plante said.
If one is interpreting correctly, this means that where fruit flies can infest Golden DeliciousTM instead of wild haw apples (hawthorn fruit), they should in time become a separate species. But did they?
According to the results, competition was much less important factor for sympatric speciation to occur than strong mate choice and the variety of resources available.Yet, even under ideal conditions, sympatric speciation occurred only a fraction of the time in the model. But that does not mean sympatric speciation is not impossible in nature, the authors argue. “Mate choice allows the population to specialize to different resources and become reproductively isolated,” Thibert-Plante said.
Okay, so speciation didn’t really happen. There is surely a typo in the report, identified in red; the writer seems to have got all the “nots” in knots, and meant to say something like “that does not mean sympatric speciation is impossible in nature, the authors argue.”
Well, if something as obviously Darwinian as sympatric speciation is strictly “impossible,” Darwinism is dead. So are they hinting that Darwinism is on life support? Thoughts?
(Citation: Thibert-Plante X, Hendry AP. Factors influencing progress toward sympatric speciation. Journal of Evolutionary Biology. Online edition 24 June 2011.)
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