direct-hit.png

Direct Hit

Theme A - Unity & Diversity

page-facing-up.png

Page Facing Up

Theme B - Form & Function

pill.png

Pill

Theme C - Interaction &  Interdependence

keycap-digit-one.png

Keycap Digit One

Theme D - Continuity & Change

Hey, Future Biologists! Today, we are going on an adventure in the world of cladograms and sequence analysis. Grab your explorer hats, and let&#39;s go!

You know how you and your siblings look a lot alike because you&#39;ve got the same parents? Now, apply that to species. Some species are more alike because they diverged (or branched off) more recently. We can tell how closely related they are by comparing base sequences of genes or amino acid sequences of proteins.

&nbsp;

Fun Fact: Did you know humans and bananas share about 50% of their DNA? Isn&#39;t genetics bananas? 🍌

In this world, we like to keep things simple. The principle of parsimony in cladistics is all about finding out how a group of species (or clade) could have evolved with the least number of sequence changes. It doesn&#39;t give us the exact history, but it shows the most probable pattern of divergence..

&nbsp;

Just like in a reality TV elimination game, parsimony says, &quot;Let&#39;s make the smallest number of changes to get to the end!&quot;

Think of cladograms as family trees, but for species. We construct these using sequence analysis. But what if we have more than one gene sequence? Well, then we get multiple cladograms! If they all show the same pattern of divergence, that&#39;s like getting a &quot;You&#39;re Right!&quot; stamp on your hypothesis of evolution.

&nbsp;

Now let&#39;s get practical. Let&#39;s say we are trying to understand the evolution of large cats 🦁🐯. You&#39;d think cats living in the same geographic region, say Africa, are more closely related than an African cat to a North American one, right?

&nbsp;

Here&#39;s how you can prove it

<ul>
	<li>Pick a gene that&#39;s conserved across many species, like &#39;cytochrome c oxidase subunit 1.&#39;</li>
	<li>Find DNA sequences for this gene for the species you&#39;re studying on the NCBI website.</li>
	<li>Collate all these sequences.</li>
	<li>Use bioinformatics software, like Clustal Omega, to perform sequence alignment and construct a phylogenetic tree.</li>
</ul>

This might sound complex, but it&#39;s just like putting together a puzzle, where each piece is a DNA sequence!

A cladogram is an evolutionary hypothesis. And parsimony analysis is like a judge that selects the most probable cladogram, where the sequence variation is accounted for with the least changes.

&nbsp;

For instance, let&#39;s say we have a DNA base &#39;cytosine&#39; that can change to &#39;thymine&#39; and then back to &#39;cytosine&#39; and &#39;thymine&#39; again. But parsimony would say, &quot;Hold on! The simplest change is just from &#39;cytosine&#39; to &#39;thymine&#39;&quot;. That&#39;s the theory we go with. The simplest explanation is most likely the true one.

&nbsp;

Think of it like this: If you hear hoofbeats, you&#39;d guess horses, not zebras, right? That&#39;s parsimony!

&nbsp;

So there you go, biologists! A journey into the world of cladograms and sequence analysis. Keep exploring, keep learning, and remember: in biology, as in life, the simplest explanation is often the best!

Theme A - Unity & Diversity

Constructing Cladograms Using DNA Sequence Analysis

Table of content

Understanding cladograms & sequences 🌲🧬

The beauty of parsimony 😌

Unlock the Full Content!

Theme A - Unity & Diversity

Constructing Cladograms Using DNA Sequence Analysis

Table of content

Understanding cladograms & sequences 🌲🧬

The beauty of parsimony 😌

Unlock the Full Content!