Blog # 4 Describe the three types of selection: directional, stabilizing and disruptive and give an example of each in your own words

Stabilizing selection favors the norm, the common, average traits in a population. Look at the Siberian Husky, a dog bred for working in the snow. Stabilizing selection has chosen a norm for the the size of the Siberian Husky. Directional selection favors those individuals who have extreme variations in traits within a population. For example people pick hounds that were the fastest in their group, from their offspring the breeders again selected the dogs that ran the fastest. By continuing this selection for those dogs, they gradually produced a dog who could run up to 64km/h (40mph). Disruptive selection, like directional selection, favors the extremes traits in a population. Disruptive selection differs in that sudden changes in the environment creates a sudden forces favoring that extreme. Think about the changes in the environment when that meteor crashed into Earth 65mya. If a plague started by the high death rate also hit these stressed animals, they would have been sorely pushed to survive. Evidence shows that they did not. So disruptive selection occurs quickly, selecting for those extreme traits that help organisms survive in the new environmental conditions.

Blog #3 Explain what microevolution is? What are the three ways that variation occurs?

Microevolution is a change in gene frequency within a population over time. This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift.
Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance. Microevolution can be contrasted with macroevolution, which is the occurrence of large-scale changes in gene frequencies in a population over a geological time period (i.e. consisting of extended microevolution). The difference is largely one of approach. Microevolution is reductionist, but macroevolution is holistic. Each approach offers different insights into the evolution process. Macroevolution can be seen as the sum of long periods of microevolution, and thus the two are qualitatively identical while being quantitatively different. Mutations alter the order of bases in the nucleotides of DNA. Mutations are likely to be rare and most mutations are probably harmful, but in some instances the new alleles can be favored by natural selection. Independent assortment (recombination of chromosomes that occurs during sexual reproduction) and the Crossing over that happens during meiosis.

Blog # 2 Why is fossil record hard to interpret?

Fossil record is hard to interpret because it is thousands to millions of years old. The older the fossil is the harder it is for paleontologists to identify what it is. Most fossils require all of the bones to figure out what kind of animal it is and the bones could be scatter all over the world. When interpreting fossils u must be careful not to break anything. Fossils can sometimes be hard or easy depending on the size of the fossil and how old it is. Interpreting fossils takes time and one must be careful not to damage/break anything.