Question

What is the most accurate way to relate species on a phylogenetic tree?

A. Count the number of functions shared by different species.
B. Analyze similarities in embryological development.
C. Use a computer to compare similarities in DNA sequences.
D. Observe the fossil record for structural similarities.

Answer 1

D

Answer 2

Correct answer would be D.

Answer 3

C

Answer 4

There are two types of diagrams that we implement in the study of homology - closeness of species as a result of having the same ancestry. The first diagram is cladogram and the other is phylogram.

Phylogram is a diagram on how related different species are based on their ancestry and lineages, which we now use DNA sequences to determine and with the aid of computer algorithms or programs like BLAST (I have an example post on what BLAST results looks like). The older way of doing it was looking at structures and possible functions of species and dug up fossils, but this proved to be causing a lot of inaccuracies since we know that two different species of very far ancestries (meaning that they are not closely related) with the aid of natural selection have been able to develop similar structures, which we refer to as analogous structures. How do we determine that they are not closely relate? We use DNA sequencing and determine the changes they have undergone.

The second diagram, cladogram, is based on estimation of phylogram but without an indication of evolutionary time for the separation of taxa.

An example of what BLAST results look like can be found on this paper I recently produced.
http://assets.openstudy.com/updates/attachments/574b4602e4b098f70ecd3ec9-nincompoop-1464551585675-lab3genophenonn.pdf

Answer 5

keywords: convergent evolution, analogous structures, homologous structures, homology, BLAST, divergent evolution.

Answer 6

http://tolweb.org/tree/learn/concepts/whatisphylogeny.html
http://www.ncbi.nlm.nih.gov/guide/homology/