Blog 7: Intro to Evolutionary Tree Project

For the second bio research project of the year, Emma and I have decided to study the evolution of bears by analyzing and researching bear evolutionary trees and cladograms. To start, we have begun preliminary research on common bear behaviors. We discovered that most bears have very good sense of smell (their strongest sense), they see and hear well, and they can run at least 37 mph. Additionally, all mothers are very protective of their cubs, their intelligence is comparable with those of the great apes, and bears treat other bears like they would humans. Most bears are also not ferocious and have a fairly calm temperament. However, some characteristics tend to vary among the different bear species. Furthermore, we have decided to specifically research hibernation and how it changes for different bears. According to our tree, there are eight bear species. We did some research on each species and wrote down whether or not they hibernate fully, semi, or not at all. Here is what we have found:
Asiatic Black– semi-hibernate
Polar– do not hibernate
Sun– do not hibernate
Sloth– do not hibernate
American Black– do hibernate
Andean (Spectacled)– do not hibernate
Giant Panda– do not hibernate
Brown– do hibernate
We are going to do more research and are hoping to discover by the end what made some bears not hibernate anymore or start hibernating. Was it environmental or gene related? Are the bears that do hibernate closer to the common ancestor? Do the bears' common ancestor(s) hibernate? We hope to answer these questions and know more about bear hibernation and how it evolved. Will keep updated as we continue to research!

Blog 6: All About Cladograms

What are cladograms and evolutionary trees?

In science, biologists frequently use evolutionary trees to study organisms. Evolutionary trees, similar to cladograms, are essentially diagrams that show the evolution of organisms. The evolution is mainly based on similarities and differences between the characteristics of the organisms. Cladograms are basically the same as evolutionary trees; however, they do not show the ancestral aspect of organisms like the evolutionary trees do. Cladograms focus more on the relations of an organism. Therefore, the organism's descendents are not present or how it has changed over time. With that said, many single cladograms can be found in evolutionary trees. Evolutionary trees add the change over time aspect to the diagram. And both diagrams are based on phylogeny: the study of evolutionary relationships.

How can scientists use these?

Scientists can use cladograms and evolutionary trees to analyze organisms and the relationships they have with other organisms. They take into account various variables like molecular evidence, biochemistry, fossils, and DNA in order to create evidence for evolution. By looking at organisms' ancestors and descendents, they can have a better understanding of certain characteristics and predict why and how they change over time. After all, the relations among organisms change constantly. Therefore, it is useful to have a consistent and uniform diagram that can help keep track and analyze those changes by classifying organisms and their similarities and differences in character with others.

Example? 

 
Here is an example of a very simple cladogram. It is normal to have a straight line and have other lines connect off of it. The letters on the main line (in this case: A, B, C, F, G, H) are the characteristics of the organisms. Most cladograms are set up this way with the characteristics on the main line with the organisms branching off of it. *the letters D and E are an exception* For this cladogram, you are supposed to classify the characteristics with the appropriate organism. However, most cladograms give you the characteristics and organisms for efficiency purposes.

While doing this exercise, it is important to look at the characteristics and classify them with the organisms. The only organisms that has a curly antennae is the butterfly, so letter H corresponds with number 8. All the organisms and characteristics are different. However, when you look at just the organisms, they share similar characteristics and look related. For example, the dragon fly and the butterfly and the ant and the spider. In order to make a cladogram, it is important to determine characteristics that organisms share in common then to establish characteristics that make them unique.

Answers:
1. F
2. C
3. A
4. G
5. E
6. D
7. B
8. H

*Why is this not an evolutionary tree? Because it does not show the ancestry of the organisms.

Source:
Cladogram Analysis. (n.d). Retrieved November 8, 2014. http://www.biologycorner.com/worksheets/cladogram.html#.VF5vVIfVm8E