Thursday, October 14, 2010

Study Shows Water Levels Affect Rate of Evolution

Climate change is an increasing issue in our global communities as it threatens the biodiversity of our planet. As the diversity of our planet is put into jeopardy, more habitats and ecosystems are threatened and as a consequence, more organisms are pushed to the brink of extinction. In order to attempt to amend possible irreparable damages done to the environment due to human impact, we must first start to understand the foundation of biodiversity and its importance.

It is a well-known fact that there are many factors that influence the diversity of our ecosystems on our planet. A few examples of these include, primarily latitude which influences temperature, altitude, precipitation, soil erosion, and productivity. It has been proven scientifically that latitude plays an important part in the evolution of biodiversity as there is much more diversification as Earth’s latitude approaches zero. The evolutionary speed hypothesis is the most common proposition used to explain evolutionary rates of diversification. It states that tropical environments, due to their abundance in energy (temperature), influence the speeding up of an ecosystem’s diversification due to greater metabolic activity. The greater the metabolic activity, the more likely mutations may occur, which cause genetic change. However the role of water accessibility has not yet been thoroughly tested as an independent variable for a contributing cause of micro-evolution, until now.

A research team led by Xavier Goldie, school of Biological Sciences, University of Auckland conducted a study to test their hypothesis that water availability directly influences the rate of genetic growth and diversity on our planet. They proposed that the greater the amount of water available in an environment, the greater the rate of metabolic function in organisms. This would result in an increasing growth of DNA evolution and therefore biodiversity. In order to test this, they compared rate of nucleotide substitution in woody plants grown in arid and mesic regions of Australia. The plants were grown in the same latitude and were as closely related as possible in order to reduce other factors that might contribute to different possible rates of genetic growth. They also were grown in similar population sizes and the distance between the arid grown plants and mesic grown plants was magnified to ensure precision when comparing results. In order to abstain from other factors besides water that could affect the rate differences, the team strongly emphasized knowledge known about the species prior to the experiment.

It was found that once the woody plants were compared, the nucleotide substitution rates in mesic grown plants were significantly higher than the plants grown in desertic conditions. Also the 76% of the species in mesic conditions displayed this variety in their nucleotide sequences. Results show that the correlation between the nucleotide substitution rate and water accessibility are parallel to that between the energy available in an environment and molecular rate divergence. Therefore, the scientific findings support the evolutionary speed hypothesis that the micro evolutionary development is based on many factors that increase metabolic rate, which increase probability of mutations and natural selection. These variables include water availability, climate weather, latitude, population size, and genetic drift.

Figure 1. Average rainfall in Australia between 1970 - 2000.

Figure 2. Number of different species of foliage in Australia.

Figure 3. Average productivity of woody plants in Australia between 1997- 2000.

As mankind continues to maintain a neglectfully extravagant lifestyle, we modify and mold our environment without realizing the consequence of our actions. Climate change is one of the most evident examples. As human development impacts our ecosystems, it is important to know exactly what our actions will cause. Using the results found in the study, we can now better predict evolutionary changes that may occur, due to water availability.

Reference List:

Goldie, Xavier, Len Gillman, Mike Crisp, and Shane Wright. "Sign In — Proceedings B."Proceedings of the Royal Society B: Biological Sciences. 12 Apr. 2010. Web. 15 Oct. 2010..


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