Evolution
Evolution is the process in which organisms have developed. Allele frequency, evidence of evolution and taxonomy have furthered scientists understanding of the ways in which organisms evolved.
Allele Frequency
Allele frequency is defined as the measure of commonality of an allele in a distinct population. Changes in allele frequency are the result of evolution. Evolution can be shaped in four ways: mutions, migration, genetic drift or natural selection.
Mutations: Alleles can change because of mutations. Mutations are caused by the miscopying of one or more nucelotides. Types of chromosomal mutations are deletion, duplication, inversion and translocation. Migration: The movement of a group of individuals from one population to another population of differently adapted organisms of the same species. This results in the genetic flow in the changing of alleles frequency. Genetic Drift: A random change in the allele frequency. Natural Selection: Organisms who are best situated for a specific environment survive due to their ability to reproduce. Less adaptive organisms fail because of their inability to reproduce. Throughout this process, the allele frequency changes. [Class Notes] Below are three types of Natural Selection: |
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Evidence of Evolution
1. Fossils: Preserved bones found in the ground. These bones show the structure of past organisms and demonstrate how they have evolved over time. Relative dating is when a fossils age is determined by its layer in the ground and exact dating is when the rocks around the fossils age are found. Both relative dating and exact dating are used to find a fossils age.
2. Geography and Species: Thousands of years ago, the world was one land mass called pangea. It is evident that similar species have evolved to fit their environment. An example of this is an Emu and a Rhea. These two species were once one identical species. Then, as pangea gradually split, the Emu evolved to survive in the African environment and the Rhea evolved to survive in the South African environment. Despite these adaptations, the two birds are still similar. The similarities of the Rhea and Emu are evidence of evolution.
3. a. Homologous Structure: Structures that are similar in organisms that share the same common ancestors.
b. Vestigial Organs: Structures that have no functions.
c. Divergent Ovulation: New habitats created new adaptions.
d. Convergent Evolution: Two unrelated organisms share the common adaptations.
e. Embryology: Embryos that are similar. This shows that many organisms have common ancestors.
4. Molecular Biology: Comparison of similar DNAs.
[Information Based on Class Notes]
Taxtonomy
Evolution of Marine Iguana's
Some scientist believe that millions of years ago a group of iguanas from South America drifted to the Galapagos islands on logs or debris from a natural disaster. Due to the islands contact with water, these iguanas evolved into a species that embraced their watery landscape. In addition, competition for resources on land forced Marine Iguanas to find food in the ocean surrounding the Galapagos Islands. [1]
SPECIAL ADAPTATIONS:
- Marine iguana skin absorbent sun thaws cold body tissue.
- Marine Iguanas use their flattened tail to swim.
- Marine Iguanas have salt water glands that they use to sneeze out salt water after a dive.
- Marine Iguanas skin change color during mating season.
- Marine Iguanas use sharp claws for climbing rocks.
- Marine Iguanas flat snout and sharp teeth help them to scrape the algae off of rocks.
- Marine Iguanas have salt water glands that clean their blood of salt which they ingest while feeding. [2]