5.6 Speciation (allopatric), Rate of Evolution and Macroevolution

Allopatric Speciation:
Allopatric Speciation occurs when a species is split or divided into two groups.
Allopatric Speciation consists of three steps:
1. A physical barrier: a species accepting a new environment.
2. Natural selection: works on both populations.
3. A new species which no longer can breed with its ancestral species.

For example: Bears.
The polar bear and grizzly bear both come from a common ancestor. But because they now live in different environments, have gone through some type of mutation (natural selection) they can no longer breed together.

 

"Speciation." Biology. Ed. Richard Robinson. New York: Macmillan Reference USA, 2009. Gale Science In Context. Web. 21 Apr. 2011.

 

Rate of Evolution:

Theory of Gradualism:

"The theory that evolution occurs gradually over millions and millions of years"

Example: When Darwin first proposed his evolution theories, he believed that evolution happened with small bits at a time, the Theory of Gradualism.

Theory of Punctuated Equilibrium:

An evolutionary theory created by Niles Eldredge (1943-) and Stephen Gould (1941-2002).

The Theory of Punctuated Equilibrium states that there are long periods in time at which evolution does not happen. Then, many evolutionary changes happen within short periods of time. The theory suggests that new species have risen very rapidly within the time frame of only a few thousand years, and then remained unchanged for millions of years after their rise.

 

"Gradualism." World of Biology. Gale, 2006. Gale Science In Context. Web. 21 Apr. 2011.

 

Macroevolution:

"[Goldschmidt] believed that the overall pattern of chromosomes and the chemical configuration of the chromosome molecule determine heredity, rather than the qualities of individual genes that make up the chromosomes."

Richard B. Goldschmidt theorized that macroevolution was where large mutations occured, therefore creating new species.

Divergent evolution:

Where plant or animal characteristics that share an evolutionary origin become distinct over time (millions-billions of years).

Example:

Human arm and bats wing. (Sound familiar? Related to homogenous features)

 

"For humans, upright walking on the ground required alterations in the foot for better speed and balance. The whale and bat modified the ancestral structure in response to environmental pressures of their own. These differing traits soon became characteristics that evolved to permit movement over the ground and in the water and air."

 

"Richard B. Goldshmmidt." World of Genetics. Gale, 2006. Gale Science In Context. Web. 21 Apr. 2011.

"Evolution, divergent." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale, 2008. Gale Science In Context. Web. 21 Apr. 2011.

5.5 Mutation and Sexual Reproduction

Mutation:

"Human male chromosomes showing mutation on chromosome 7." World of Genetics. Gale, 2010. Gale Science In Context. Web. 19 Apr. 2011. 

"Photomicrograph of human chromosomes showing male mutation on gene 7, which determines cystic fibrosis."

A mutation is the change of DNA. Mutation can be neutral, harmful or beneficial. 

Neutral Mutation: A mutation that has no effect on the organism. Example: One brown eye-color and one blue eye-color. 

Harmful Mutation: A mutation which reduces an organisms reproductive success. Example: down syndrome and cystic fibrosis (human diseases) 

Beneficial Mutation: A mutation which improves or enhances reproductive success. Example: 

"A specific 32 base pair deletion in human CCR5 (CCR5-Δ32) confers HIV resistance to homozygotes and delays AIDS onset in heterozygotes."

"Mutation." World of Genetics. Gale, 2007. Gale Science In Context. Web. 19 Apr. 2011.

"Mutation." Wikipedia. N.p., n.d. Web. 19 Apr. 2011. <http://en.wikipedia.org/
     wiki/Mutation#Beneficial_mutations>.

Sexual Reproduction:

"Sexual reproduction is the creation of new individuals resulting from the joining of the nuclei of two separate 

sex cells (sperm and egg)." 

Gene Pool:

A gene pool is the genetic material in a population of "sexually reproducing organisms." Small gene pools have 

more of a tendency to die quicker compared to larger gene pools. 

"Gene pool." World of Biology. Gale, 2006. Gale Science In Context. Web. 19 Apr. 2011.

"Reproduction, sexual." World of Biology. Gale, 2006. Gale Science In Context. Web. 19 Apr. 2011.

5.4 Lamarckism and Darwins Theory of Natural Selection

Lamarckism:


Jean-Baptiste Lamarck created a theory before Darwin which began the ideology of evolution. His theory is called the "Lamarckism Theory". According to Lamarck, if an organism desires a certain trait or has a certain characteristic, its offspring will have that trait or characteristic. For example: If a human had lots of muscle from being very physically active, that humans child will have a lot of muscle as well. 
Through biochemistry and the laws of physics, scientists declined this theory. Eventually, if a trait is not helping an organism survive and declining that species population, that certain trait will be eliminated. But it cannot occur as quick as one generation, it takes up to millions of years. 


"Lamarckism." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale, 2008. Gale Science In Context. Web. 19 Apr. 2011. 


Darwin's Theory of Natural Selection:
Darwin's theory of natural selection acts to accumulate minor genetic changes to an organism to help them advance in survival. If a member of a species developed a "functional advantage", the offspring will inherit that advantage and pass it on to their own offspring. Darwin also explains how overpopulation helps natural selection causing the weak to die off or struggle to survive and only the strong or fittest surviving, in other words, survival of the fittest. 

Example: Darwin and his famous study of finches- each had different types of beaks. The longer, stronger beak was more preferred compared to the shorter, weaker beaks. In order for an organism to grow, the less desired trait must die. Because the weaker, shorter beaked finches could not peck bugs out of the trees for food, they died off because of starvation. So the survival of the fittest comes into play, and therefore the "fittest" trait of the finches would be the stronger and longer beaked birds. 

"Darwin's Theory Of Evolution." All About Science . N.p., n.d. Web. 19 Apr.
     2011. <http://www.darwins-theory-of-evolution.com/>.

5.3 Homologous Structures, Embryology, Vestigial Features, and Biochemistry

Homologous Structures:
Homologous structures are structures that share the same or similar physical structure but serve as different functions. 
For example:
A whales fin, a human arm and a bats wing.
They all have a similar structure, but completely different roles.


"Homologous structures." World of Anatomy and Physiology. Gale, 2007. Gale Science In Context. Web. 17 Apr. 2011.


Embryology:
"Embryology is the study of the development of organisms."  For example: A human and a pig have the same (close to identical) embryos. So because of this relation, humans are somehow related to pigs in our ancestral line (humans and pigs have a shared ancestry). 


"Embryology." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale, 2008. Gale Science In Context. Web. 17 Apr. 2011.


Vestigial Features:
An organ or a structure is "considered" vestigial if it is not used anymore to the extent it was used in the past. That organism has evolved, and the new evolved species still carries their vestigial structure but does not use it. 

Example: 

Whales have hipbones. This shows that in earlier generations, whales had legs. But because they do not need it anymore, they now do not have them and only contain hip bones. 

Example:

Humans still have an appendix. Although scientists are not sure as to what we used our appendix for in the past (it is guessed we used our appendix to digest raw meat) it is proven that our appendix is of no use to humans now. 

"However, evolution tends to eliminate useless organs, for every structure requires energy to grow, sustain, and transport." 

"Vestigial structures." World of Anatomy and Physiology. Gale, 2007. Gale Science In Context. Web. 18 Apr. 2011.

Biochemistry:

"Biochemistry is the study of the chemistry of living organisms." It it a new concept, but its  principles have been used by humans in the past.
Example:
- Yeast in bread
- fermenting wine
Eventually important advances in Biology were discovered through the study of Biochemistry. Some of these advances are DNA and the laws of genetics. These were all from what the main emphasis of what defines the study of Biochemistry... amino acids.
Less similar overall = less similar amino acids. 
-  Exploring areas such as Artificial Selection: more desirable traits. If humans can change traits, so can the environment. 
Example:
Humans have close to equal numbers of amino acids compared to monkeys. So this must mean that we may have come from a common ancestor.

"Biochemistry." World of Chemistry. Gale, 2008. Gale Science In Context. Web. 18 Apr. 2011.

5.2 Paleontology, Radiometric Dating, and Biogeography

Paleontology:

http://schools-wikipedia.org/images/329/32942.jpg

All over the world, there are fossils waiting to be discovered. However, they are so hard to find that we only have found about a truck load. Paleontology is the study of life which is through fossils.
A common misconception about fossils is how they are formed or made. Fossils are not bones, they are minerals which over time form into rocks. To begin with, the animals bones are eventually buried under soil. Through the soil minerals from water seep through resulting in the bone becoming a mineral. With the eventual addition of pressure from the soil, the mineral will harden into rock. Fossils can completely change a Paleontologists views or a hypothesis of how life was in the past. It is the evidence of the past. The evidence of evolution.


"Paleontology." Earth Sciences for Students. Detroit: Macmillan Reference USA, 2010. Gale Science In Context. Web. 11 Apr. 2011.


Radiometric dating:

“All radiometric dating is based on the fact that a radiometric substance, through its characteristic disintegration, eventually transmutes into a stable nuclide.”

Radiometric dating is an efficient way for scientists to discover a fossil or rocks age. It works like popcorn- begins slow, rapidly speeds up, then slows again and eventually stops. So how does this work? Lets take Uranium for example. Overtime, Uranium atoms eventually “transmute” into a more stable atom, Lead. Scientists compare the amount Uranium ions to the amount Lead atoms to discover a rock/fossils half-life. The more Lead there is, the older the specimen. With this knowledge, it opens up a world of opportunities for scientists to discover and explore. 

"Radioactive dating." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale, 2011. Gale Science In Context. Web. 12 Apr. 2011.

Biogeography:

Why do different species live in the area(s) they do now? “Biogeography is the study of why plant and animal species live in different regions of the Earth.” It is split into two different categories. Historical (past history and evolution of a species) and also Ecological (a species environment). 

“Biogeographers explain the distributions of species using four basic principles regarding the nature of Earth and the organisms that live on it:

Environmental variability: For a variety of reasons, the conditions that organisms experience change considerably across the surface of the Earth. Climate and elevation are two major influences.

Ecological limitation: Every organism has a limited range of conditions that must be met in order to allow it to live and reproduce. Since a species is a population of reproductively compatible organisms that have similar biological properties, no species can be found everywhere.

Continental drift: The locations of landmasses across Earth's surface have not remained the same, but have changed slowly over the geological history of the Earth. Therefore, the conditions experienced by organisms change over long periods.

Evolutionary change: Species do not stay the same over time, but are in a constant state of change as individuals best able to survive and reproduce within certain environments become more frequent, while others less capable die or fail to produce offspring. The ability of a species to evolve allows it to persist over long periods of time and track the changes occurring on the surface of the Earth.”    

"Biogeography." Biology. Ed. Richard Robinson. New York: Macmillan Reference USA, 2009. Gale Science In Context. Web. 13 Apr. 2011.

For Example:

The Biogeography of the Tiger Salamander (Ambystoma Tigrinum):

http://sweb.uky.edu/~dweis2/The_Weisrock_Lab/Research_files/Tiger%20Salamander%20Map.jpg 

5.1 Taxonomy and Linnaeus Classification

In the study of Evolution, it is important to be aware of an organism's Taxonomy. To begin with, what is Taxonomy? "Taxonomy is the study of the classification of organisms, according to their differences and similarities."Included in Taxonomy are categories such as kingdom, phylum, class, order, family, genus, and species.


Another way of classifying a living organism is to use Linnaeus Classification (Binomial Nomenclature). Having latin names for all living organisms helps foreign scientists all over the world to identify the organisms with ease. 


Some Examples of Cetacean Animals: 


Atlantic Spotted Dolphin (Stenella Frontalis) -
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Stenella
Species: frontalis




Blue Whale (Balaenoptera Musculus) - 
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera
Species: musculus 




Fraser's Dolphin (Lagenodelphis Hosei) -
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Dolphinidae
Genus: Lagenodelphis
Species: hosei




"Taxonomy." World of Biology. Gale, 2007. Gale Science In Context. Web. 7 Apr. 2011.


"Fraser's Dolphin (Lagenodelphis hosei)." NOAA Fisheries. N.p., n.d. Web. 7 Apr.
     2011. <http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/
     frasersdolphin.htm>.


"Blue Whale (Balaenoptera musculus)." NOAA Fisheries. N.p., n.d. Web. 7 Apr.
     2011. <http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/
     bluewhale.htm>.


"Atlantic Spotted Dolphin (Stenella frontalis)." NOAA Fisheries. N.p., n.d. Web.
     7 Apr. 2011. <http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/
     spotteddolphin_atlantic.htm >.