Blog #7: Biome Comparison

Desert Biome:

• Hot in the day
• Very little precipitation. The little precipitation comes in rain.
• Tend to be near the equator.
• Plants and animals have evolved for life in the desert.

Tundra Biome:

• Very cold.
• Precipitation is in snow.
• Far from the equator.
• Ground is frozen under called permafrost.
• Plants and animals have evolved for life in the cold.

Blog #6: Which Level of a Food Pyramid is the Most Important?

I think that the plants/producers group is the most important group. It is the first group on the whole pyramid. Without it, the group above would suffer from a food shortage and die off. Therefore, causing a chain reaction all the way up to the top.

Blog #5: Are Humans Impacting the 6th Extinction Event?

Throughout Earth's history, there have been five major extinction events. Because of those events, many species either became endangered or extinct. But all of those events occurred due to a certain cause. There lately has been talk that humans may cause the next extinction event with pollution and such. I think it is completely possible that it could cause a major extinction event in the distant future with the effects of pollution. But that's not the only possibility, I think that another could also be caused by natural events such as major ocean level changes and asteroid impacts.

Blog #4: The Three Types of Selection

1. Stabilizing Selection

• Stabilizing selection is when the selective pressures select against the two extremes of a trait. Because of that a population experiences stabilizing selection. An example of this can be seen in plants. For example, one plant may be too short too thrive while another may be too tall. When combined, these too plants maintain a medium height. 

The effect of stabilizing selection on trait distribution.

     2.  Directional Selection

• Directional selection is when one extreme of the trait distribution experiences selection against it. Because of this, the population's trait distribution shifts toward the other extreme. Examples can be seen in giraffe necks. Shorter necks can't reach certain leaves, so in response, distribution of neck length shifts to those with longer necks.

The effect of directional selection on trait distribution.

     3.  Disruptive Selection

• Disruptive selection is when selection pressures act against those in the middle of the trait distribution. The result is a bimodal. An example can be seen in flowers. For example, one type of flower has variable heights and is pollinated by three different pollinators. One that prefers short plants, one that prefers medium plants, and one that prefers tall plants. If the medium sized height liking pollinator was to disappear from the area, the population would grow more short and tall plants.

The effect of disruptive selection on trait distribution.

Blog #3: What is Microevolution?

Microevolution is a change in gene frequency within a population. The four ways that that variation occurs are: selection, mutation, genetic drift, and gene flow. 

Blog #2: Why are Fossil Records Hard to Interpret?

Fossil records can be hard to interpret because of the fact that they could be deteriorated to the point where they are un-examinable.

Blog #1: Why is Evolution a Theory and not a Law?

In science a fact overwhelms a theory because a law is a widespread fact that has never ending evidence. A theory, on the other hand, is not exactly proven but is supported and believed my many scientists. Evolution is a theory because there is a bunch of evidence that supports it.