Mike the Mad Biologist

Confusing Ecological Interactions and Natural Selection Gives Me the Williwillies

Posted by Mike on April 23, 2007
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ScienceBlogling Mike Dunford has an interesting post asking whether we should save an endemic Hawaiian plant, the williwilli. It’s a good post, but I have two comments, one silly and one serious. The silly comment is that how could anyone let a plant named the williwilli become extinct? It’s so damn cute (and is the plural williwillies?) Onto the serious point.

The reason that the williwilli is in trouble is because an invasive, non-native gall wasp is parasitizing the williwilli. Mike writes:

…if the invasive species outcompetes the natives, resulting in the extinction of the native species, it is simply a case of natural selection.

Here’s the serious point: I don’t think calling this natural selection is accurate. This is an example of an ecological interaction, parasitism. While the survival of the williwilli is affected, this interaction isn’t natural selection. For natural selection to be taking place, gall wasp parasitism must result in the differential survival of williwillies. In other words, plants that are more resistant to the wasps must replace plants that are more sensitive to the wasps as a result of the parasitism. Mind you, this could be happening, but I haven’t found any papers suggesting this.

To paraphrase Freud, sometimes parasitism is just parasitism.

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Comments

  1. #1 coturnix
    April 23, 2007

    Species selection, to play the Devil’s advocate (and potentially save Mike)?

  2. #2 D. Knox
    April 23, 2007

    Just to let you know, it’s wiliwili. Check back to your Mike Dunford post. Hawaiian never has two consecutive “L”s.

  3. #3 Joshua
    April 23, 2007

    Yeah, D. Knox has it.

    The guys over at Agricultural Biodiversity Weblog might also have some things to say about the idea of letting a plant species go extinct because “it’s natural selection”. (Actually, I’m a little surprised they haven’y mentioned the Wiliwili. Maybe that’s because they’re more focussed specifically on crop plants.)

    And then there’s the naturalistic fallacy aspect. Sure, the extinction may be “natural”, but that doesn’t answer the question of whether it’s good.

    Mike actually seems to cover that distinction rather nicely in his post.

  4. #4 Edward
    April 23, 2007

    Pick up on what Joshua said: I think it is natural selection. I take issue with the whole idea that humans are not part of nature and the environment. Comet strikes, mass extinctions, and human disruptions of the evnvironment are all part of nature. On the other hand, many organisms develop symbiotic relationships, so if humans manage to save the wiliwili because we think the plant is cute or because we want to maintain biodiversity, that’s also nature. In general, I think it’s a good idea to try to minimize human impact on the environment and maintain genetic diversity, but that’s because I think that’s the path that offers the best chance for continued evolution of our own species.

  6. #6 bitkisel ürünler
    May 18, 2009

    Pick up on what Joshua said: I think it is natural selection. I take issue with the whole idea that humans are not part of nature and the environment. Comet strikes, mass extinctions, and human disruptions of the evnvironment are all part of nature. On the other hand, many organisms develop symbiotic relationships, so if humans manage to save the wiliwili because we think the plant is cute or because we want to maintain biodiversity, that’s also nature. In general, I think it’s a good idea to try to minimize human impact on the environment and maintain genetic diversity, but that’s because I think that’s the path that offers the best chance for continued evolution of our own species.