Biodiversity Revisited

Now in that last post, there was a description of biodiversity, but so what? I recommend you read the comments to that one because they were really interesting. In fact the more comments you post the better. I find them fascinating.

What leads to high biodiversity? (courtesy of notes from a lecture by the brilliant Paul Alaback)
1. competition
2. resource availability
3. disturbance
4. time, history
5. equitability of climate
6. heterogeneity of habitats
7. population interactions.

How bout that another list of SEVEN items. Well, I talked about one of these things in my previous post: population interactions and how they can be threatened by development, i.e. bears that can't get past the highway. This concept specifically refers to members of different populations breeding together.

The other ones however I didn't really talk about, providing instead a rather static view of biodiversity, though I illustrated an idea about biodiversity helping Earth reinvent for the future, I will now discuss the way the past influences present biodiversity.

1. competition is the result of two species inhabiting the same niche in an ecosystem. This is not good for either species, so they become more specialized, one species keying into some habitat element that the other cannot, usually rather than changing its niche entirely, a species will become more common in what was once an extreme edge of its range.

2. resource availability, namely high resource availability causes high biodiversity. Jungle has more diversity than desert because there is more water for example.

3.Disturbances such as fire result in higher biodiversity over time because there are species dependant on disturbances that you will not see without disturbance. Disturbances increase nutrient availability in soil, and just give new life forms a chance to colonize an area that was previously too shady to inhabit for example. Disturbance changes the playing field so new organisms have a chance.

4.time, history. Evolution takes time. All other factors being equal, the longer there has been life somewhere the more diversity you can expect.

5. equitability of climate. Think North Pole versus Vermont. VT has way more diversity, because our land is hospitable to a wider range of species.

6. heterogeneity of habitats. Every species has its own niche that it lives in (very simplified) and the more variation in a site, the more niches there are. For example if there is a flat plain and a rolling rumbling, rocky plain, you'll see more diversity in the latter because of small microsites that occur. Differences in shade, effective precipitation (see Soils Lab is Fun! post), soil qualities, sun angle and so on.

7. population interactions. Interbreeding between distinct populations of organisms that creates a larger gene pool.

I think that if you took all these factors and somehow tried to mix them all together and find the perfect ecosystem for biodiversity, you'd describe a landscape with varied topography, long growing seasons, lots of water, lots of nutrients, large tracts of land where populations can interact without boundaries, and a place that has been inhabited by life for a very long time and is affected by various disturbances that keep refreshing the system.

Does it make sense that people are worried about saving the rainforest? The Amazon meets all these characteristics. The North pole does not.

Let's think about this critically though. Because the North pole doesn't have even a fraction of a percent of the diversity that the Amazon has does that mean it isn't valuable for Earth's diversity? NON, MES AMIS!

It is very important, if Biodiversity really is "the ability of the Earth to reinvent itself" then think of that storage of beneficial genes that are adapted to eternal ice age, dwelling at the Earth's top. If there is another ice age, it will not be the jungle butterflies that repopulate the earth, it will be the polar bears.

more on diversity to come, keep the comments rollin' in that's what the campground's for.