The Making of the Fittest: Natural Selection and Adaptation

Transcription

1 The Making of the Fittest: Natural Selection and Adaptation (Ex.ofRock Pocket Mouse) The Making the Fittest: Natural Selection and Adaptation ( Ex. Rock Pocket Mouse) Myles L., Daira C., Azza G., and Shakira A. Myles L., Daira C., Azza G., and Shakira A.

2 Background Found throughout the southwestern part of the United States Well adaptable to dry, rocky, and desert environments Claim small territories Solitary Heteromyidae family (rodents) An excellent model organism for studying geographic variation in Scientific name: Chaetodipus intermedius phenotypes within a single species

3 Summary The film introduces the pocket mice, who tends live in a variety of areas in New Mexico s desert including lighter sands and darker lava rock. Mice with darker fur on the top of their bodies began to appear and camouflage with dark lava rocks from predators. Mutations, random and rare events, were most likely the known cause. Researchers conducted an experiment by gathering the DNA from light and dark mice taken from one desert region. They aimed to find one or more genetic mutations that cause the dark coloration.

4 Continuation Mutations in an organism are never good or bad they re either favored, rejected, or neutral depending upon an organism s environment. A mutation in the Mc1r gene, which controls the amount of dark pigment in a mouse s hair follicles, caused the mouse to grow dark fur. Dark environments allowed the dark colored mice to survive better and have more offspring. Approaches the misconception that evolution is a random process. We know mutations are random, but natural selection is the exact opposite. Different mutations may cause the same phenotype.

5 Key Concepts A mutation is a random change to an organism s DNA sequence. Mutations that increase the fitness of an organism increase in frequency in a population. Different mutations in the same gene and even mutations in different genes, can result in the same phenotype Mutations can be random but Natural Selection is NOT random

6 MORE Key Concepts The environment contributes to determining whether a mutation is advantageous, damaging, or neutral. Evolution can happen quickly, superior genetic mutations can increase in frequency in a population rapidly, even if the fitness advantage to the organism is small. Selective pressure depends on the environment in which an organism lives, meaning that other organisms in the environment (in this case, the predators) can be a selective force

7 Two Discussion You have probably wondered why camouflage is important for species that are active at night like the rock pocket mouse. It s important because night active predators like owls are able to recognize color differences at night which makes camouflaging necessary. Points Dark coloration gives an advantage even on a light-colored environment. Dark-colored mice tend to be well hidden unless they run across light-colored areas. While with light-colored mice on dark-colored surroundings the mice tend to stand out. Because dark coloration is helpful in this environment, more mice with the dark-color mutation survive to reproduce, and pass on their genes.

8 Is the following statement true or false? Mutations are caused by selective pressure in the environment.

9 Environment contributes to determining Environment whethercontributes a mutationtoisdetermining whether a mutation is A. advantageous A. advantageous B. damaging B. damaging C. neutral C. neutral D. all of the above D. all of the above

10 Researches found a mutation in the gene and what did it control?