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Convergent evolution in ferns

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From ScienceDaily:

This ecosystem, known as the páramo, was created relatively recently (around 3 to 5 million years ago), when the Andes underwent a major uplifting event. This provided new ecological opportunities for plants to exploit and flourish in. Other plants from North America and temperate southern regions were also able to colonise these new páramo environments.

In contrast to the archetypal tropical rainforest, where trees are tall and some plants have huge leaves, the páramos are more exposed, tundra-like biomes where plants are short and have much smaller leaves, some of which are very hairy.

Dr Sanchez-Baracaldo of Bristol’s School of Geographical Sciences said: “These ferns are remarkable because, in geological terms, they quickly evolved a new morphology as a response to new and extreme environmental conditions. It’s fascinating to notice that, by a process known as convergent evolution, whereby similar features evolve independently in species of different lineages, cloud forest ferns arrived at the same ‘solution’ in response to the same environmental pressures.”

Hmmmm. Are there laws of convergent evolution? Readers?

Here’s the abstract:

The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude páramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Páramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the páramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among páramo than non-páramo lineages supporting the hypothesis of adaptation and divergence in the unique Páramo biodiversity hotspot. Public access

See also: Convergent evolution again: Squid bioluminescence evolved multiple times Bencze: This convergent evolution is so astonishingly unlikely that we would never expect it to occur via the evolutionary mechanism of random mutation and natural selection.

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Moose, I agree balance is required. I was being a little snarky and too confident in my comment. Let me modify it by saying that I think that each example of convergence presents a small, medium or big challenge to darwinism. Perhaps each of those challenges can be met, but that the number of convergences grow and the disparity of species grows wider, the stronger the challenge to darwinism it is. Collin
Collin, I think balance needs to be taken when looking at convergent evolution. First, Darwin considered convergence as a natural expectation of his theory. A certain amount of convergence is very consistent with the neo-Darwinian model. Where it gets unbelievable is when the convergence is significantly beyond what chance + necessity would realistically allow. That seemed to be the conclusion in the previous post about squid. I think if we jump all over every evidence of convergence as proof against neo-Darwinism, it makes us look ignorant. Moose Dr
Are there "processes" of convergent evolution? I thought that "convergent evolution" was just a fancy term for "same feature in unrelated species." It puts the label of "evolution" on it so you don't have to worry about thinking about how a common designer might reuse the same design. Collin
Ferns are guided by fractals like many other distinct life forms. More "Convergent "Evolution"". http://raimalarter.blogspot.com/2009/01/fractals-in-nature.html?m=1 ppolish

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