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Fri July 11, 2014
We often think of different scientific disciplines as existing in isolation from one another, but in reality they are interconnected. For example, Astronomy is the study of space and the objects within. These objects are made from atoms, and can be investigated though chemistry. They follow the laws of Physics. Earth is one of those objects. Earth’s biologic organisms evolved and are influenced by the various expressions of geology, and life has altered the geology of the Earth.
Nathan Lyons, a PhD student at North Carolina State University in the Department of Marine, Earth and Atmospheric Sciences, is using this principle to investigate geologic events by teasing out elements of biology.
My research takes place in the Olympic Mountains of Western Washington State. I am researching large mountainous regions that are along plate tectonic boundaries, how climate and tectonics change the landscape.
The study of earth’s surface arrangement is known as geomorphology, and it is primarily influenced by geology and climate.
The reason that there are numerous waterfalls in the Clearwater River drainage basin, is that this whole mountain chain has been uplifted over time, and at the same time river is responding to climate. So that's created different rates of incision along the river. And where the two different rates incision, contrast is where a waterfall forms. The Clearwater River which is the river that I'm researching in the Olympic Mountains has lowered due to climate. When the temperature changes drastically, such as between interglacial and glacial periods, glacial periods will have less stream discharge and sentiment and that's what really causes a River to cut down into the landscape. During warmer interglacial periods where there's more sediment more water discharge coming down the stream that's going to cause the river to incise more which is going to steepen those hill slopes adjacent to the river, and perhaps induce more landslides
Nathan and his team are using some of the region’s biologic organisms to date these events. The method is affectionately nicknamed “Fish Tectonics”.
We use a really neat method with fish. We use the genetics of fish to date waterfalls. So waterfalls separate the fish along the main river from the top above the waterfall. And so by looking at their genetics we can back calculate how long the fish have been separated, so how long that waterfall has been around.
In general, We can use genetics to trace evolutionary changes in plant and animal populations. here’s how:
Plant and animal cells are powered by mitochondria. In animals mitochondria are inherited only from the mother, and they have their very own DNA, separate from the rest of the cell. Because animals inherit mitochondrial DNA from only one parent, there are no changes that would occur due to the mixing of genes from two parents. You, your brother and your sister and you all share the same mitochondrial DNA from your mother. As mitochondrial DNA gets passed down from mother to child over generations, it changes slightly through mutation. This happens at a predictable rate, and so an organism’s lineage can be traced through time to a common female ancestor. This can also be used to tell, for example, how far removed you are from your cousin, your 3rd cousin, your next door neighbor or your family dog. In this way we can date occurrences of changes in a species.
With mitochondrial DNA what we can do is compare the fish above and contrast it with the genetics of fish below the waterfalls. Before these waterfalls were around the genetics were pretty similar but now that there is a waterfall between them, their genetics have gone into two different pathways. And so by determining how much difference there is, we can determine how long they’ve been separated from each other.
So, what is one of the most interesting lessons to come out of Nathan's research?
What we are really finding with this research and similar research is that science subjects like geology and biology are actually very closely entwined. So when we see the topography change due to climate or tectonics, we see these chain reactions that move throughout the landscape and we're recognizing that biology very much co-evolves with geology.