Compare and contrast Mechanisms of Evolutionary change.
“Evolution is the most profound and powerful idea to have been conceived in the last two centuries” (Mayr E 2002)
The concept of evolution has been debated throughout time. “Evolution is change in the properties of populations of organisms over time”. Based on evidence available the theories of evolution have themselves evolved. As theories on evolution expanded it created a divide within the scientific communities. Palaeontologists and Evolutionary biologists study evolution as two divisions Microevolution and Macroevolution. “Microevolution refers to varieties within a given type. Change happens within a group, but the descendant is clearly of the same type as the ancestor. This might better be called variation, or adaptation, but the changes are "horizontal" in effect, not "vertical””(Morris, J DR, 2012). Typical theories to explain the genetic variation is natural selection, gene flow and genetic drift. “Macroevolution refers to major evolutionary changes over time, the origin of new types of organisms from previously existing, but different, ancestral types” (Morris, J DR, 2012). Macro evolution uses the mechanisms common descent and speciation to depict long periods of little change (stasis) then sudden short periods of change (punctuation). Micro evolution can also be influential historical trends if given enough time. Fossils, radiometric dating and molecular clocks are all used to provide evidence of evolutionary trends. (University of California Museum of Palaeontology. 2004)
Since Aristotle’s statement of “infinite duration” (Mayr E) the idea was widely accepted that Earth had always existed and simply revolved through cycles or periods of state. The world encountered Creationism during the 18th century (Mayer E) through religion and the teachings of Genesis in the Bible. People turned to the belief that there was one Creator that made the universe and all the individual organisms to live in perfect harmony. The lack of scientific knowledge and this reliance on religious preaching meant we dated the world at around 6000 years old and the power religion held over society made this the predominant theory for many years. It wasn’t until the discovery of fossils and contradictory scientific evidence in the 17th and 18th centuries that dated the Earth as 4500 million years old and outlined the evolution of different organisms. This supported the idea that the world was actually an ever-changing entity as suggested by Charles Darwin in the 19th century. This shook creationism to the core. It led all members of society to question how the world has become the form it is today.
Common Descent describes a steady and naturalistic change over time from one form of species into the current version we observe today. Although fossil records demonstrate variation in species there is substantial links missing from the fossil record. “most palaeontologists found themselves facing a situation in which there were only gaps in the fossil record, with no evidence of transformational evolutionary intermediates between documented fossil species” (Schwartz, Jeffrey H., 1999). These large gaps in knowledge and evidence create difficulties in classification of organisms and tracing the evolutionary path. Scientists today rely on a series of parameters to record the 1.8million species presently uncovered, this can also allow us to draw parallels and recognise relationships between organisms. We can use this as a tool to measure evolutionary distances and create “phylogenetic trees” (Class handouts, 2012). The taxonomy of life is something that has evolved over time to the standard we have today. This began in the 18th century. “In 1735, Linnaeus published an influential book entitled Systema Naturae and is still the basic framework for all taxonomy in the biological sciences today” (O'Neil, D. (2012). Life is classified in levels, starting with Life itself and then...
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