Evidence for Evolution Convergent and Divergent Evolution
The Story...Toby was a young adventurous Joey who livedin the Australian outback with his Mum, Dadand three sisters. Toby loved hearing storieswas interested in hearing more about hisheritage. He became interested in developinghis understanding of how Kangaroos haveevolved over time and where they came from. Toby
Toby’s parents were not able to tell him much exceptthat their family had been living in Alice Springs for thepast 100 years. This did not satisfy Tody’s intrigue andso he set out determined to find some more answers.Joey had no idea of where to begin his investigationbut knew that his teachers at school always hadanswers. So his first stop was to visit his favouriteteacher at school Mr Amos. Mr Amos was Toby’sscience teacher and Joey recalled learning aboutancestry the previous term. Toby thought that MrAmos must be able to help him out somehow! Off Joeywent in search of Mr Amos and hopefully someanswers! Mr Amos
Hi Toby. To what do I owe thisHi Mr Amos! pleasure of have you visit me on your day off?”
Well Mr Amos I’m trying Well Joey I’m veryto research my ancestry impressed that you are soand figure out where they interested in your ancestry.came from but I need Do you remember what weyour help because I don’t talked about last termknow where to start!” when we were learning about ancestry.
Do I ever Mr Amos. Welearnt about how species evolve and palaeontologists who Very good Joey. I’m very look at comparative impressed with how much anatomy to figure out you remember.”major lineages of species.
Thank you Mr Amos but Well Joey it just so happenshow will this help me that a close friend offigure out my ancestry?” mine, Samantha, is a palaeontologist who I’m sure would be more than happy to have a look into your ancestry with you.
Gees Mr Amos that wouldbe fantastic! Thank-you! No worries Joey. I’m glad I could help. Good luck in your quest for information!”
So off Toby went to meet Samantha. He wasvery excited about this as the prospect offinally learning something about his ancestrywas in close reach!
Samantha greeted Toby with open arms. She wasvery excited to see him as Mr Amos had calledahead and informed her that Toby was on his wayover. Samantha loved visitors and embraced anyopportunity she had to talk about her love andpassion of palaeontology. Samantha had aparticular interest in the area of comparativeanatomy and so was very keen to look into Toby’sancestry and determine how comparativeanatomy has played a part in the evolution ofToby’s family. Samantha
Why hello young Toby! I’m veryexcited that you have come to Sounds good Samantha.visit me and that you have I’m very interested totaken an interest in my work. learn about anything toLet’s start by providing you with do with ancestry.some background informationabout comparative anatomy soyou know how and why its used.
1. Alright lets get started! 2. It is assumed that groupsComparative anatomy is about with little in common have Wow like how itsestablishing relationships on the diverged from a common believed that treebasis of structural similarities and ancestor much earlier in Kangaroos evolved fromdifferences. Palaeontologists geological history compared Possums because theyresearch comparative anatomy as a to groups that have a lot in both use their tails .means of determining how closely common.related species are. 3. Comparative anatomists look for structures in species which although may serve different functions are fundamentally similar, and therefore suggests a common origin. These are called homologous structures.
That’s a perfect example Toby. Great work!Comparative anatomists look at three Cool so they look at thingsthings when trying to determine whether like the shape of a kangaroosor not two structures or homologous or tail and how this has evolvednot. These are their relative as well as the developmentpositions, gross morphology, studying the of the embryo to determineshape and general appearance or form of how different structures mayan organism and histological have similarities.”appearance, the appearance of the tissuesof the body of an organism.
Exactly right Toby. Your showing a fantastic Animals are said to evolve in two So this is like what theyunderstanding already!” different ways. These are referred to as say has happened with divergent and convergent evolution. our pouch. It evolved Divergent evolution occurs when the from another species and same species splits into two or more Kangaroos adapted it to descendant species due to developing enable survival in their new characteristics to enable them to survive in their new and differing new environment. habitats. This means that species that were once similar or related then become more and more dissimilar. The newly produced organisms have certain features in common with each other and with the ancestral stock from which they arose and this forms the basis of what we call homology.
1. Exactly right. That’s a perfect 3. The other type of example of divergent evolution evolution, convergent , occurs when Toby. We call the result of divergent complete organisms (or their parts) evolution adaptive radiation, the come to resemble each other more process whereby populations move closely than their ancestors (orinto new environments and undergo ancestral structures) did, as a result o rapid evolution as they adapt to the their sharing similar environments. unexploited habitats. 2. Comparative anatomists construct evolutionary trees which illustrates adaptive radiation in which branches represent separate lines of descent from a common ancestor. The more similar two organisms are, the more recently they are assumed to have diverged.
So like how both Kangaroos The anatomical similarity and Wombats have both between species is said not to evolved to have sharp claws be caused by common ancestry for digging in Australia’s dry but by the fact that structures climate. Their claws are anthat perform the same functions analogous structure. And an are likely to resemble one example of convergent another to a degree. These evolution would again be structures are described as possums and tree kangaroos. analogous.
Excellent! You’ve got a really good Thanks Samantha! You understanding now. I have been a great help!think I have given youenough information to do a bit of your own investigating! Good luck!