DINOSAURS- BIRDS:
FISH
ELEPHANTS
PRIMATES- HUMANS
Tuesday, February 19, 2013
What is Evolution?
Evolution is the growth or development of a certain species over time. Evolution can occur in most living species such as humans, birds,dogs, and etc. It is the theory that argues all the organisms alive on earth today share a common ancestor. For example:
DINOSAURS- BIRDS:
DINOSAURS- BIRDS:
Evidence of Evolution
There is a numerous amount of evidence that supports Evolution. Below are some examples of evidence that Evolution may have existed:
Homologous structure: These are body parts that are alike because the species share a common ancestor. These structures may serve the same or different functions. For example, the wing of a bird and the arm of a human have very different functions, but are homologous structures because of the evolutionary relationship between birds and humans.
Examples:
Fossils: The remains of an organism in history, preserved in a petrified form, or as a mold.
Examples:
Vestigal Structures: Structures of an organism, that over time have little or no uses and become smaller, or even disappear.
Homologous structure: These are body parts that are alike because the species share a common ancestor. These structures may serve the same or different functions. For example, the wing of a bird and the arm of a human have very different functions, but are homologous structures because of the evolutionary relationship between birds and humans.
Examples:
Fossils: The remains of an organism in history, preserved in a petrified form, or as a mold.
Examples:
Vestigal Structures: Structures of an organism, that over time have little or no uses and become smaller, or even disappear.
Monday, February 18, 2013
How did Darwin come up with the theory of natural selection?
Charles Darwin, one of the most popular scientists in history, was well known for his theory on natural selection. Natural selection is when nature chooses or
" selects" which organisms survive. In other words, if their
adaptations help them to survive, then they pass on
their genes to their offspring. If their adaptations don't allow this,
then they starve or are killed off. In 1861, Darwin ventured out to the coastal South America with aristocrat Robert Fitzroy.Darwin ended up spending most of the trip exploring the wildlife of South America, mainly the Galapagos islands.While on the islands, Darwin saw many animal species that he had never seen before in England. Darwin began to pay attention
to the various species on the island, and he noticed
that finches, a common bird species, were slightly different on every
island. The main difference was their beak sizes. Some had small beaks, while others had large beaks. This affected their dietary habits, and the size of food they ate. For example, small beaked birds would survive in an environment with only small seeds, where as large beaked birds wouldn't. ( more difficult for birds with large beaks). This would lead to their starvation, and at one point, they would die out.
What is Genetic Variation?
Genetic variation is the genetic differences there are within a population or certain species. Genetic variation is important because it it provides the genes for natural selection. Natural selection is the theory that suggests that an organism's genes give it a greater chance of surviving, and therefore, they live, and then they pass on their genes to their offspring and future generations. For example, if a population is exposed to a new disease, selection will help the organism resist the disease if it has the genetic material required. However,
if the organism doesn't have the " correct" genes,the
population will not evolve and could be wiped out by the disease. Genetic variation is pretty much the raw material of evolution, in other words, without it, organisms wouldn't be able to evolve, and at some point, may become extinct. Therefore, the risk of a species becoming endangered, increases due to low genetic variation.
What are Mutations and Adaptations?
Mutations:
Mutations are when the structure of a gene is changed or "mutated". In other words, your DNA sequence is altered. Most of the mutations that we think matter to evolution are "naturally-occurring. For example, when a cell divides, it makes a copy of its DNA, however, sometimes the copy is not perfect. That small difference from the original DNA sequence is a mutation. Below are some examples of mutations:
Adaptations:
An adaptation is a physical or behavioral trait that has developed to allow an organism to survive in its environment or habitat. Adaptations are the result of evolution and may occur when a gene mutates, or alters. That mutation helps the organism survive and reproduce, and it passes on that trait to its offspring. One example of an adaptation would be a crab's shell. This shell protects it from predators and from crashing waves.
Mutations are when the structure of a gene is changed or "mutated". In other words, your DNA sequence is altered. Most of the mutations that we think matter to evolution are "naturally-occurring. For example, when a cell divides, it makes a copy of its DNA, however, sometimes the copy is not perfect. That small difference from the original DNA sequence is a mutation. Below are some examples of mutations:
Adaptations:
An adaptation is a physical or behavioral trait that has developed to allow an organism to survive in its environment or habitat. Adaptations are the result of evolution and may occur when a gene mutates, or alters. That mutation helps the organism survive and reproduce, and it passes on that trait to its offspring. One example of an adaptation would be a crab's shell. This shell protects it from predators and from crashing waves.
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