Learning Targets Explain the purpose of a cladogram

Learning Targets �Explain the purpose of a cladogram and use a cladogram to explain evolutionary relationships between species. �Describe hominid evolution and the relationship between hominids and other primate species.

Cladograms and Primates: Evolutionary Relationships

Cladograms �Cladograms are diagrams that depict the evolutionary relationships among species using shared ancestral and derived traits. ◦ The relationships may be based on physical appearances: phenotypes.

Word origin �Cladogram is derived from the word clade: a group of organisms that includes an ancestor and all descendants of that ancestor. It is the branches on the cladogram. (Origin from the Greek: klados meaning branch. )

Traits �Shared derived trait: ◦ a feature that is not found in other groups of descendants of a common ancestor. ◦ Ex. Hair is a feature shared by mammals, but not found in non-mammalian vertebrates.

How to build a cladogram �http: //ccl. northwestern. edu/simevolutio n/obonu/cladograms/Open-This. File. swf �Oldest events are usually at the bottom with the modern species at the top. �The branches are based on evidence from: ◦ fossil record ◦ comparative anatomy ◦ biochemistry

Nodes �A point on a cladogram where a single ancestral line breaks into two or more descendent lines.

Try Building a Cladogram Lancelet Clouded Tree Salamander Frog Lamprey Salmon Red Fox No ir Ha il Ta ur Fo lki wa ng s leg ed ng Hi mn olu lc a br rte jaw Ve Lancelet Lamprey Salmon Clouded Salamander Tree Frog Red Fox

Which point represents the nearest common ancestor to the gorilla and elephant? • Point a is the nearest common ancestor.

Primate Evolution �In terms of the geologic time scale the evolution of humans has occurred relatively recently. The common ancestor of all primates, which are mammals with flexible hands and feet, forward-facing eyes, and large brains, probably arose around 65 million years ago.

Primate Evolution ◦ Primates are divided into two groups: anthropoids and prosimians. �Anthropoids are divided into hominoids (Humans, Apes gibbons, orangutans, gorillas, and our closest relative, the chimpanzee) and Old World Monkeys and New World Monkeys. �Prosimians are the oldest living primate group, most are small and active at night (lemurs, lorises, and tarsiers). �The important distinction is that we do not “come from monkeys, ” rather we share a common ancestor.

Primate Evolution

Primate Evolution �Homo sapiens (the scientific name for modern humans) arose nearly 200, 000 years ago ◦ A unique feature of humans is being bipedal, or having the ability to walk upright, which is significant because it allows for reaching higher into trees and frees hands for using tools. ◦ Homo sapiens also have a significantly larger cranium (skull) allowing for the development of a much larger brain.

Primate Evolution � Numerous fossils of extinct hominids exist: ◦ Australopithecus afarensis ◦ Homo habilis ◦ Homo neanderthalensis � All share a recent common ancestor to modern day humans.

Primate Evolution �Notice that Homo sapiens (humans), Homo habilis, and Homo neanderthalensis all have much larger craniums, which means larger brains than Australopithecus afarensis, which was an earlier hominid. Australopithecus afarensis Homo habilis Homo neanderthalensis Homo sapiens

Cladogram Worksheet �Complete Cladogram practice worksheet, turn in to tray with name on it once done. �Start Virtual Hominid Lab. ◦ ◦ Textbook Website: my. hrw. com Username: badger Password: d 9 f 4 d Go to chapter 12 Student Premium Multimedia Labs and Activities Virtual Labs Comparing Hominoid skulls. COMPLETE WORKSHEET THAT GOES WITH LAB.