Disruptive Selection Vs Directional Selection Essay

Both directional and disruptive selection show the distribution of phenotypes. Distribution selection takes place when an extreme phenotype is favored, and the distribution curve shifts in that direction. Antibiotic resistant bacteria are an example of directional selection. When an antibiotic is used, some bacteria may survive causing it to produce bacteria that is resistant to that antibiotic.
Disruptive selection occurs when two or more extreme phenotypes are favored over an intermediate phenotype. An example would be a bird with a large beak, who can handle large seeds and a bird with a small beak that can handle small seeds. A bird with an intermediate size beak cannot handle small or large seeds.

2. Antibiotic resistant bacteria evolve in two ways, either through a random mutation or by bacteria swapping antibiotic resistant genes. With the increased use of antibiotics, bacteria that have the resistant genes will survive,
The major evolutionary trends that developed among major vertebrate groups, that allowed for transition from aquatic to terrestrial life are the following. The first trend involved improved respiration and the formation of jaws. The second trend is the formation of jointed vertebrae limbs which allowed the first chordate to make their way to the land environment. The third trend involved the transitioning to a more suitable reproductive method such as the laying of amniotic eggs, which contains amniotic fluids that mimic an aquatic environment necessary for development. In mammals, the formation of the uterus allows the young to develop and mature inside the female and allows her to move actively around. The last trend is the development of hair and mammary glands. These trends are characteristic of mammals since they are endothermic and generate internal heat. Hair, provides insulation against heat loss and allows mammals to be active in cold weather. Mammary glands enable females to feed their young without them leaving to find