Ecology: The study of interactions and relationships between living things and their environment.
Evolution: The change in a species over time
Evolution Website http://www.pbs.org/wgbh/evolution/
Homologous Structures
Homologous structures are skeletal structures that are the same/similar even though the function may be different in different species. An example of this is the forelimbs of humans and bats, birds, whales, cats, etc. They have the same embryonic origin and could very possibly indicate evolution from a common ancestor.
Analogous Structures
Analogous structures are structures from different species that show similar function but not the same structures and have evolved independently. These structures from different species do not share a common ancestor. The fins of a fish and the flippers of a whale which are both used for swimming but have no similar structures, are analogous structures as are the wings of a butterfly and the wings of a bat which are both used to fly but have no similar structures.
Vestigial Structures
Vestigial structures or organs are various parts in a body (cells, tissues, bones, organs) which no longer function in the same way that the trait functioned in it's ancestor. A vestigial structure can arise when an environment changes and that trait is no longer as advantageous to the organism. Whales still have remnants of hip bones, they had ancestors that walked on land. Humans have a tailbone or coccyx which is a small set of fused vertebrae that exist at the base of the pelvis. For our ancestors, it most likely formed a tail that was capable of grabbing branches and helping with balance as they climbed trees. As we evolved into bipeds (walking on two legs on the ground) and spent less time in the trees the need for a tail was diminished in our changing environment. This can be seen in the transition from monkeys to great apes, the loss of a tail represents a less tree-based lifestyle. Wisdom teeth in humans is another example of a vestigial structure. The human skull has been shrinking as we evolve, partially because our diet has become much softer and easier to chew (we cook or otherwise process our food). While the human jaw has become smaller, the last tooth in the jaw has not been lost. In most people these teeth cause pain as they come in and may even deform other teeth in the jaw.
Charles Darwin
Charles Darwin was a naturalist and biologist who is known for his theory of evolution and the process of natural selection. In 1831 he embarked on a five-year voyage around the world on the HMS Beagle; where he surveyed everything he saw and even kept hundreds of specimens which he studied and led him to formulate his theories. In 1859, he published his book On the Origin of Species. Darwin's theory of evolution that he states in his book states that species survived through a process called NATURAL SELECTION where those that successfully adapted, or evolved, to meet the changing environment survived and passed on their traits through reproduction while those that failed to evolve don't survive or reproduce. Through observations and studies of birds, plants and fossils, Darwin noticed similarities among species all over the globe, along with variations based on specific locations, leading him to believe that the species we know today had gradually evolved from common ancestors. Darwin’s theory of evolution and the process of natural selection later became known simply as “Darwinism.”
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