Life has been given seven biological characteristics, lets see if I can remember them.
Growth.
response to stimuli.
reproduction.
metabolism.
organization. (being composed of one or more cells)
adaptation.
homeostasis. (internal changes maintain state in spite of external forces.)
These were taught to me in Biology class in high school by Mr. Tom Sabo. He was a great teacher with a sturdy mind and a great sense of humor, but not even he could truly define life. Sure an organism has all of these characteristics, but what is life itself?
In Neal Stephenson's book Cryptonomicon, he describes any life form as a "stupendous badass" descended from millions generations of stupendous badasses that went before. Stephenson is not a biologist, but he is right on the money. Life aint easy. It's full of struggle as we all know, and simply carrying viable DNA against all the odds is a tremendous honor and an incomprehensible privilege.
My ecology professor, Paul Alaback brought up the mind boggling topic of genetic ecology. From this discussion, I thought of the question.
"Can we think of the conservation of biodiversity to be the conservation of all the individual genetic combinations that occur?"
The answer without hesitation was yes. This is exactly how we can think about biodiversity.
Take away all the landforms and all the life forms in your favorite wild place, park, natural area, backyard, whatever. Replace the spatial dimensions with a three dimensional grid. Now in place of all the life, imagine the unique double helices present at every point on the grid. There will be trillions in the soil, billions floating in the air, one for each tree, rodent or bird. Each one is like a spiraling computer generated image that was designed in the late nineties to illustrate DNA to school kids, and they are all different colors. If you zoom in on one it will dissolve into GATC patterns linked together with supple ladder rungs. If you analyze this image you will come up with the figure: number of DNA combinations/unit volume. Or you could lay all the molecules end to end and simply calculate: length of DNA/unit volume.
Now we have a relatively static view that encompasses the three dimensions of space plus the quantity of DNA. What if we watch this figure for a longer time?
For one year. Even watching just one strand of DNA that exists in a flower at the edge of a stream. Most of the year it stays constant, contorting slightly under stress of mutation, perhaps only momentarily, but when it starts its cycle of reproduction in the spring, hundreds of new combinations of DNA appear near the plants top. They form delicately and abundantly, each pollen grain and ovum with half the DNA of the parent plant.
When these pollen grains combine with the ova of another flower, there is suddenly a new combination of genes with new properties and new adaptations. This offspring may grant the the chance to reinvent its species, perchance to carry it through the apocalypse.
A man who did extensive biodiversity studies in some tropical islands spoke at my school. If only I could remember his name. He said, "Biodiversity is the Earth's ability to reinvent itself."
How true it is, and the idea is completely dependent on this flow, and exchange, the process of combinations and recombinations, mistakes and opportunities. Imagine however that our reproducing flower is part of an isolated population of its species it is still trying as hard as it can to recombine its genes for its survival, but it is like trying to multiply without using the numbers 4,5, and 6, there are many fewer combinations and therefore less potential to overcome a change in its environment.
This is what happens when populations are cut off from each other. Highways that inhibit animal migration can cut a gene pool in half for example. Even mountains that rise up over time can separate populations and cause new species to develop on either side like immigrants to America forced into changing their names and identities.
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4 comments:
so many things are living that those seven parameters exclude. how can something that okays a role in nature not be considered living? does an abiotic factor effect life differently than a biotic factor?
As a former mathematics major, I was fascinated by your description of a 3 dimension Cartesian graph of DNA, though really it would be 4 dimensions since you can count time as a dimension (it's harder to visualize, but makes sense mathematically).
It got me thinking. Wouldn't it be better to plot your DNA with radial coordinates? Instead of x, y, z measuring height, width, and depth from an arbitrary point, why not phi, psi, and R; that is, longitude, latitude, and distance from the center of the earth? That strikes me as a more biological centric model, since similar organisms tend to hover around the same range of R.
I once briefly considered studying the crossover field of biology and mathematics, but it ended up being more statistics than I cared for. Perhaps I should have chosen otherwise?
That's really interesting, matt. I like the cut of your jib. I'm more of a naturalist than a mathematician so I appreciate the new perspective. You'd end up with a really interesting image there. Imagine a computer program like google earth where you could see all these glowing points all over the world, click on one and view the genetic code! That would be the ultimate tool in biodiversity conservation.
Now as I wrote that I was trying to work time into it, but I realized it would become a very long post. From your mathematical perspective, what is the most logical way to observe biodiversity over time? I like the idea of a graph that has "number of DNA combos in a certain area" for the Y axis, and then "Time" on the X axis.
But there must be more interesting ways to think about it. Cumulative genetic codes in one area over time? I tried to think of it like a rate of evolution in a way.
DNA(m)/Area(cubic m)/Time (seconds)
thoughts?
Funny you should ask that. When mathematics failed to make me rich and famous, I went back for a second degree in cartography and Geographic Information Systems. Now I am a GIS programmer. Many years ago I studied all about how to present multi-dimensional data, but today I rarely get to do it or think about it.
Your question "what is the most logical way to observe biodiversity over time?" doesn't have a single answer. It depends on the questions you want to ask.
The advantage to a formula like DNA(m)/Area(cubic m)/Time (seconds) is that is does show something useful and interesting and can be conveniently charted on a map (assuming you ignore the three dimensional component of different species living on top of one another, especially in the ocean). But ultimately I think it is too simple. For example, an area may have a constant value of 200 species per acre over a long period of time, but some species may be going extinct while new ones are forming. And the population of some may decline while others grow. Your metric doesn't capture this. Also, the significance of a population size is species dependent - 100 is a large elephant population but a small E. coli population.
I would be more likely to want to plot poulation density PER SPECIES over time and then compare these variables to each other and to other inputs. But this is multi-dimensional statistics, looking for correlations, and gets away from mapping. I believe you have to do this sort of mathematics first and then present the results visually. A map is limited to one or two variables beyond latitude and longitude. If you look at a map and notice a pattern, that can lead you to think you know more than you really do. A map is good for hypothesizing, but it isn't proof. The dog wags the tail, not the tail wagging the dog.
So what sorts of questions do people interested in observing biodiversity ask?
Just rambling. Probably not the answer you were looking for, but you can see I tend to view things as maps and mathematics. When all you have is a hammer, every problem looks like a nail.
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