Answer:
1. Stabilizing Selection
2. Directional Selection
3. Disruptive Selection
Explanation:
Stabilizing Selection
This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for. If we look at a distribution of traits in the population, it is noticeable that a standard distribution is followed:
Example: For a plant, the plants that are very tall are exposed to more wind and are at risk of being blown over. The plants that are very short fail to get enough sunlight to prosper. Therefore, the plants that are a middle height between the two get both enough sunlight and protection from the wind.
Directional Selection
This type of natural selection occurs when selective pressures are working in favour of one extreme of a trait. Therefore when looking at a distribution of traits in a population, a graph tends to lean more to one side:
Example: Giraffes with the longest necks are able to reach more leaves to each. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait.
Disruptive Selection
This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait. This type of selection is not as common. When looking at a trait distribution, there are two higher peaks on both ends with a minimum in the middle as such:
Example: An area that has black, white and grey bunnies contains both black and white rocks. Both the traits for white and black will be favored by natural selection since they both prove useful for camouflage. The intermediate trait of grey does not prove as useful and therefore selective pressures act against the trait.
Biology is the study of living thing
Which statement best summarizes how classification systems have changed over time?
Classification systems have become more complex to allow for all the discoveries made about organisms.
1. Contraction of the iliacus and psoas major produces flexion of the hip joint
2. quadriceps femoris muscle group
3. A combination of gluteal and thigh muscles also adduct, abduct, and rotate the thigh and lower leg. The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh.
4. triceps brachii
5. The major muscle that laterally flexes and rotates the head is the sternocleidomastoid
6. Rectus abdominis
7. The external obliques are the outermost abdominal muscles. They are also key participants in spinal flexion and the compression of the viscera. Individually, they act alongside the internal obliques in lateral flexion and spinal rotation.
8. abdominal external oblique muscle
9. external intercostal muscles
