Delicate woodland fern discovered in the mountains of France is the love child of two distantly-related groups of plants that haven’t interbred in 60 million years, genetic analyses show.
For most plants and animals, reuniting after such a long hiatus is thought to be impossible due to genetic and other incompatibilities between species that develop over time.
Reproducing after such a long evolutionary breakup is akin to an elephant hybridizing with a manatee, or a human with a lemur, said co-author Kathleen Pryer, who directs the Duke University Herbarium.
To their surprise, genetic analyses revealed that the fern was the result of a cross between an oak fern and a fragile fern — two distantly related groups that co-occur across much of the northern hemisphere, but stopped exchanging genes and split into separate lineages some 60 million years ago.
Other studies have documented instances of tree frog species that proved capable of producing offspring after going their separate ways for 34 million years, and sunfish who hybridized after nearly 40 million years, but until now those were the most extreme reunions ever recorded.
The researchers suggest that, because ferns require only wind or water to reproduce, they take longer to speciate. That sounds pretty lame, actually.
The fact is, Darwinian evolution didn’t happen. No evolution happened. But it was supposed to.
By the way, the tree frog and sunfish are vertebrates that reproduce via mating in the animal sense, no? They don’t just need wind and water. Yet look at the time span after which some are still compatible.
What we need, of course, is more Darwin in the schools, until people lose the ability to recognize a problem when they see one.
Abstract: A fern from the French Pyrenees—×Cystocarpium roskamianum—is a recently formed intergeneric hybrid between parental lineages that diverged from each other approximately 60 million years ago (mya; 95% highest posterior density: 40.2–76.2 mya). This is an extraordinarily deep hybridization event, roughly akin to an elephant hybridizing with a manatee or a human with a lemur. In the context of other reported deep hybrids, this finding suggests that populations of ferns, and other plants with abiotically mediated fertilization, may evolve reproductive incompatibilities more slowly, perhaps because they lack many of the premating isolation mechanisms that characterize most other groups of organisms. This conclusion implies that major features of Earth’s biodiversity—such as the relatively small number of species of ferns compared to those of angiosperms—may be, in part, an indirect by-product of this slower “speciation clock” rather than a direct consequence of adaptive innovations by the more diverse lineages.
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