Homology / Analogy

1a. Briefly describe the two different species that possess the homologus trait.

                Humans and Whales

1b.  This image shows how evolution has shaped hand bones to perform different functions. Human hands have evolved to grab and hold things, while whale "hands" have evolved into flippers to help with swimming.

1c.  Below you will find the image of a tree-climbing, insect-eating beast that weighed between 6 and 245 grams and gave birth to one hairless baby at a time.  According to a new study, this is the common ancestor of all placental mammals.  If we look at the conceptual image we can see the same hand like structure of our human and whale.  I would not make assumptions (of course further research is necessary) however, I would wager the “hand” structure would be similar to the human and whale “hand” structure that we are looking at now.

     

2a. Briefly describe the two different species that possess the analogous trait.

  The turtle and the snail.

2b. The similar analogous trait that both of these species share is they both have their “shell”; the hard exterior casing on the top of each creature for protection. Both species can shrink inside of their shell which helps protect them from any outside threats,  however, the snail’s shell is secreted by specialized glands in the mantle whereas the turtle shell is modified skin.  

2c.   Actually in 2008 a team of scientists had reported the discovery of the oldest aquatic turtle, dating back 164 million years that only had a half shell which only covered it’s belly leaving it’s back unprotected.  This turtle species that swam in China's coastal waters 220 million years ago is the oldest turtle known to date. 

The first snails were limpet like mollusks who lived in shallow water.  They fed on algae and their digestive tract ended at the back end of the body.

2d.

Protein Synthesis

GACTACCAAGGTAGTGGCCCCAGTTTGAAGTGCATCAAG

Have fun and good luck.

Malthus and his influence on Charles Darwin

I believe that the individual that had the greatest positive influence on Charles Darwin’s development of his theory of natural selection, was Rev. Thomas Robert Malthus.

Thomas Malthus was a political economist who wrote “Essay on the Principle of Population” (1798), in which he argued “population will always tend to outrun the growth of production. The increase of population will take place, if unchecked, in a geometric progression, while the means of subsistence will increase in only an arithmetic progression. Population will always expand to the limit of subsistence and will be held there by famine, war, and ill health. Vice, misery, and self-restraint alone could check this excessive growth.” (Malthusian Theory). Stated simply, people can produce more offspring that can possibly survive and will if left unchecked. According to WWW.UCMP.BERKELEY.EDU, Darwin wrote in his 1876 autobiography, “In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work".

The bullet point that identifies with Malthus’ work is: “Resources are limited”. As Malthus stated in “Essay on the Principle of Population” all populations suffer because they produce more offspring than there are resources. Populations increase exponentially, but the amount of resources is generally finite. The example given by the professor is a great example; a population of bunnies could grow exponentially, but there is only so much food, water and shelter to sustain them. Darwin (and also Alfred Russel Wallace) took this further and surmised that siblings would have to compete, and only those individuals who were best suited to obtain the necessary resources would survive. Those individuals would pass their favorable traits to their offspring and so on and so on, “favorable variations would tend to be preserved, and unfavorable ones to be destroyed”, natural selection at work.

As you can see from the above quote from Darwin’s autobiography, Darwin was heavily influenced by Malthus’ work. I don’t know if I would say Darwin couldn’t have developed his theory of natural selection without Malthus’ influence, but I believe it gave him (and Wallace) an epiphany he may have taken a while longer to get to.

Darwin delayed publication of his book “On the Origin of Species” for 20 years. Though there are several theories for this delay, the prominent theory suggests that Darwin was well aware of the affect his work would have on the scientific and religious communities of his time. Darwin himself wrote that his theory was “like admitting to a murder”, the murder of Christianity. I’m sure Darwin knew all too well the backlash he would receive from the church and the religious society as a whole and he was in no hurry to subject himself or his family to the public ridicule or denunciation by the church he expected from the publication of his theory.

Desert Island Survival Kit

If I were stranded on a desert island, the two items I would take with me would be a knife and a water filter. The knife for use in making shelter, protection and hunting and the water filter to eliminate any impurities in any water source and make it suitable for consumption.