We've all talked about the study of life before, but have we take the time to really think about how it all flows together? Maybe your theory is different than mine, maybe they're not so different. Either way we all have our own way of thinking how the evolutionary process started, and how it was found out. While doing some research of my own I came across two causes; Comparative morphology and Macroevolution.
Comparative morphology is the systematic study of similarities and differences in body plans between major groups. Scientists started studying this in the 18th century. By doing this they got a closer look at bone structures and physical appearances of life forms. A study performed to look at comparative morphology would be to compare the pelvic structure of a manatee, but there was no need for a pelvic structure because they don’t walk. However, they did find out that sea manatees do in fact have a ghost socket where a pelvic structure would be found. They found out that there was in fact intermediate fossils found that gave evidence to there being such a thing as a “land manatee.” The fossils contained many of the same characteristics of sea manatees, but their pelvic structured showed that they were able to walk!
Charles Darwin, a great scientists, embarked on a voyage across the sea to South America in 1831 where he studied the diverse life on all the different islands. When Darwin went back to England, he noticed that he had discovered some fossils of extinct animals. It wasn't until he took a good look at them that he realized that some of the new species he examined resembled the extinct animals. He looked through his drawings and notes and noticed that not all of the species were alike, but they did show variation in size, color, and many other characteristics. Darwin was able to formulate a theory that included variation, a huge part of Darwin’s conclusion because variation would enable the species to survive and reproduce in certain environments.
Darwin proposed that an environment would “select” specific characteristics for a species to possess. This is known today as natural selection. Since then, variations in traits have been shown to be controlled by genes in DNA. Microevolution occurs when little changes in allele frequencies are brought about by mutation of genes, genetic drift, migration, and natural selection. When mutation in genes occurs, the result is a change in the DNA structure, which is heritable. This occurrence is the source for diversity in species and organisms. Gene flow and genetic drift is also a contribution to the diversity of things. When alleles leave or enter a population, as a result of immigration or emigration, it is called gene flow. This idea is much like genetic drift, however, genetic drift is brought about by chance only. This size of a population affects the diversity of genetic drift because of the fact that small populations are more likely to loose alleles completely.
Macroevolution is large-scale patterns, trends, and rates at a broader view. Examples that fall under this are fossil records, comparative morphology, and biochemistry. Scientists use sedimentary rock sequences as geological time scales to define eras and eons. Comparative morphology uses fossils as well as existing life to form similarities that show evolutionary relationships among groups. Scientists identify differences and similarities between species on a molecular level by doing this. They can look at how one strand of DNA pairs with another from a different species, and form some kind of an idea of the evolutionary distance between the two tested.
In my opinion, both of these are good studies to the keys to life and evolution. You can see time and age first, then different structures of species and compare them to modern day species. We are all the same, just look at our DNA! We must have come from one common ancestor. I think that these studies show us a lot about the world, as well as ourselves!
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