Question

Which two organisms are most closely related?

Answer 1

how do i read this?
http://prntscr.com/6zain7

Answer 2

@aaronq

Answer 3

@poopsiedoodle

Answer 4

@Phebe

Answer 5

@leonardo0430

Answer 6

sorry its blocked for me :T

Answer 7

http://takeexam.next.ecollege.com/ec/pub/K12Content/Courses/resources/swfs/media/Ninth_Grade/Science/Unit6244/Lesson35319/VHS_BIO_S2_03_20_phylo_tree.gif

Answer 8

.-.

Answer 9

oh

Answer 10

even though you can't see it can you still tell me how to read a phylogentic tree?

Answer 11

Read this
http://evolution.berkeley.edu/evolibrary/article/phylogenetics_02

Answer 12

Okay, this tree has a root. That little line that fades out at the bottom of the tree. This is of great importance. All rooted trees make a inherent statement of time. For all rooted trees, as you move from the root to the tips (in this case the top of the tree) you move to the present. So, near the root is the oldest and near the tips is the youngest.

Keep in mind we don't know the scale or length of time we are talking about, usually. Meaning, does your tree depict events over 1 billion years? 2 billion? We cannot be sure with just a tree.

Now for terminology. We know the root. Each place the tree branches is called a "node". Nodes represent both a split (usually speciation), and the most recent common ancestor of all organisms that come from that node. This tree is arranged vertically, so we can ignore any horizontal lines, they are just for easier viewing. I have made a small diagram for you:

Now, to find the most recent common ancestor of two species. I have a simple method. Put a finger on each of the two species or groups in question and move from them towards the root of the tree. Move along the lines and NEVER go back towards the species and away from the root. This means one finger may have to stop well before the other. Where they meet is the most recent common ancestor of the two groups/species/genes in question.

Answer 13

More specific to your question, if each node is the most recent common ancestor of the groups from it, and we now know that we go backwards in time as we move towards the root, which node is the youngest? Recall that this node is the furthest away from the root.