Week 3: Analogy/Homology

Homologous:

1a. Two species that possess a homologous trait are frogs and lizards with their forelimbs. Frogs are amphibians that mostly live near moist wetlands while lizards are reptiles that live in more dry regions.

1b. The forelimbs of a frog are used for a multitude of things, but most notably for locomotion (both land and water), balance when standing/sitting and absorbing shock from high impact stress on the body.


The forelimbs of a lizard are used almost strictly for locomotion on land, however, there are other lesser known uses for them such as hunting, scavenging and feeding.

1c. The common ancestor between these two had to have been some sort of large reptile. When part of the population was forced to live near large masses of water, it adapted its forelimbs to accommodate the change in environment.

2a. Two species that share an analogous trait are humans and octopi. Both species use eyes for seeing, but both sets of eyes have adapted for completely different environments.

2b. Human eyes are used only for vision. They are adapted mostly for environments where sunlight or some substitute is present. There is a clear periphery where vision gets blurred and blind spots where the eye cannot see due to placement on the human.



Octopus eyes are also only used for vision. However, they are adapted for the deep sea where there is not sunlight. Also different from humans is that they do not have a blind spot, meaning that they can see everything around them.



2c. The common ancestor between these two must have the analogous trait because both of the structures are used for the same thing (vision), however they act different because they are adapted differently to their respective environments.

Protein Synthesis

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Week One: Historical Influences on Darwin

1. I believe that Jean-Baptiste Lamarck influenced Darwin's theory the most because of his idea that the environment surrounding the species played a large and crucial role in their evolution. Lamarck believed that a species would lose body parts that were not in use and change body parts that were heavily used to further enable their survival.

2. Jean-Baptiste Lamarck's view on evolution was one that has been torn down for it's biological inaccuracy for years, but it does have its merits. Lamarck believed that all living things evolved into more "perfect beings", enhancing their strong parts and eradicating their weak ones. He explained a point in which as an organism lives and changes, it's adaptations would be passed down from generation to generation. This was only half true, as only the traits that are able to be passed down would be present in the offspring. This is where Lamarck gets most of the negative critique for his explanation. http://www.pbs.org/wgbh/evolution/library/02/3/l_023_01.html

3. The bullet points "Organisms with better access to resources will be more successful in their reproductive efforts", "Who gets better access to these resources?", and "If the environment changes, the traits that are helpful or adaptive to that environment" all are related to Lamarck's idea that as resources and environments change, so do the organisms that rely on them. The population will adapt to survive if one of these variables is altered. The points "In order for natural selection to occur, reproduction must occur" and "In order for traits to evolve and change, they must be heritable" also speak to the part of Lamarck's hypothesis that has warranted him so much criticism. While it may be true that species adapt and change throughout their lifetime, the traits that change also must be able to be passed down through the genetic makeup within the sex cells. So in this case, Lamarck was wrong in saying that any and all adaptations that occurred within an organisms lifetime would be passed down to its offspring.

4. I personally do not think that Darwin would have been able to explain natural select without the ideas of Lamarck. Without his views on adaptation and environmental change, Darwin's hypothesis would not be as testable or falsifiable as it was. It is very simple to alter the environment of a test subject to see what kinds of changes occur. However, it is almost arbitrary what will happen without controlling the environmental change or even having any environmental change at all.

5. Darwin's book was, unsurprisingly, not well-received by the church. As a group of highly religious people, reading a book that indirectly shot down the beliefs that they were raised on threatened them greatly. Even to this day, there is a clear divide between science and religion.