Evolution Case

Name: Hoang Anh Vu (vu.95)

Class: Biology 1101

T.A: Jason Macrander

Final Evolution Paper Assignment

Question 1:

What is evolution? And what does it mean when we hear the term "evolution by natural selection"? Firstly, evolution is the gradual genetic development of different kinds of organisms on Earth from simple to more complex forms (Futuyma 2004). Secondly, natural selection is the process in which individuals with adaptive characteristics to the current environment tend to survive and reproduce more than the rest in that population (Futuyma 2004). These individuals would pass their inheritable genetic characteristics to their offspring; thus, lead to the evolutionary change from generation to generation (Futuyma 2004). Three important conditions to Charles Darwin's evolution by natural selection are: variation, inheritance, and differential survival and reproduction (Chiuchiu 2013). In order to know thoroughly the evolution by natural selection, I would take an example of Cane Toads (Bufo Marinus), evolutionary species by natural selection occurring during the past 200 years. Cane Toad is one of the most invasive species that covers about one-third of Australia's land area (Than 2006). Cane Toad is an amphibious species, with a dry warty skin, and an average size of 15 cm (Cameron 2012). It varies in colors such as grey, yellow, olive-brown, red-brown; male Cane Toad is smaller than female one and this species usually sit upright and move in short rapid jumps (Cameron 2012). In 1935, some people in Australia brought Cane Toads from Hawaii to control the spread of beetles which are detrimental to their sugar cane crops; however, these toads turned to the pests themselves (Than 2006). These species even invaded so quickly that they take over more than 30 miles a year nowadays. However, these species do not develop similarly from time to time; instead, the researchers have found out that newer population of cane toads develop longer legs (6 percent longer than average) than their last populations (Than 2006). To understand the incredibly fast invasion of cane toads in Australia, TEAM BUFO had applied Darwin's evolutionary concepts by natural selection to study more about this unique species. Dr. Ben Phillips of TEAM BUFO spent most of his time building mathematical models and measuring toads. For his study, Phillips had collected cane toads from four different variations, ten toads from northern Queensland, and the other three are from nearby areas. He took these toads to the place named Middle Point where he fitted them with radio tags then released them. The radio tags help the Dr. Phillips to follow the toads' process (Gill 2010). The result suggests that when the toads spread all over Australia's land areas, they automatically sort themselves in different levels of moving speed (SBI 2011). You can understand Phillips's idea by thinking this way: slower toads are left behind, whereas the quicker ones are running at front. To further support his idea of genetic and inherited characteristics in cane toad's speed, Dr. Phillips studied one more generation (Gill 2010). This time, he allowed the toads in the same population to breed each other and set up ratio tags for the new offspring to see if they receive the heritability (Gill 2010). The result indicates that the offspring does inherit the ability to move quickly from their parents. This phenomenon, in which strong toads breed with each other and produce fast-moving toads, is called "Olympic Village Effect" (SBI 2011). Therefore, in the next generation, only toads with better fitness which is quick speed characteristic are generated at the invasion front; thus, the average speed of toads gradually increases from year to year. In Phillips' experiment, the final results show that due to mutation, the toads first arrived to the destination had bigger bodies (bigger toads are quicker), longer legs (longer-legged toads are quicker) and extremely active during day & night (SBI 2011).

Question 2:

Hans Eiberg at the University of Copenhagen once said "Originally, we all had brown eyes" (Bryner 2008). However, about 6,000 - 10,000 years ago, someone who lived near Black Sea had developed a genetic mutation that would be able to turn brown eyes into blue eyes (Hullinger 2012). Therefore, there is a group of researchers studying about the genetic mutation that lead to this eye color evolution in human. This mutation affected the OCA2 gene in our human's chromosomes, where mainly produces melanin, the pigments necessary to our hairs', eyes', and skin's colors (Bryner 2008). The mutation, however, does not completely turns off the gene; instead, it reduces the amount of melanin in the iris and dilutes brown eyes