Cladistics Part 1: Constructing Cladograms

The video tutorial explores phylogeny and cladistics, explaining how organisms are classified based on evolutionary relationships. It introduces cladograms as tools to visualize these relationships and discusses ancestral and derived characteristics. The tutorial also covers convergent evolution and provides a step-by-step guide to constructing a cladogram, using examples to illustrate key concepts.

What is the primary purpose of a cladogram?

• To display the physical characteristics of animals

• To show the geographical distribution of species

• To illustrate the evolutionary relationships between organisms

• To list all known species in a region

In a cladogram, what does the term 'outgroup' refer to?

• A group of organisms that do not share a specific ancestral characteristic with the in-group

• A group of organisms that are the most evolved

• A group of organisms that share all characteristics with the in-group

• A group of organisms that are extinct

Which characteristic is shared by all members of the order Carnivora in the cladogram?

• Warm-bloodedness

• Presence of feathers

• Carnivorous meat-eating teeth

• Ability to fly

What is a synapomorphy?

• A characteristic unique to a single species

• A derived characteristic shared by all members of a clade

• A characteristic found only in the outgroup

• A characteristic that has been lost over time

When constructing a cladogram, why might the characteristic of flight not be used to separate birds from crocodiles?

• Because birds and crocodiles are not closely related

• Because flight is a result of convergent evolution

• Because flight is a characteristic of all reptiles

• Because crocodiles can also fly

Which of the following is an example of convergent evolution?

• Birds and crocodiles sharing a common ancestor

• Leopards and domestic cats having retractable claws

• Humans and frogs both having a spine

• Butterflies and birds both having the ability to fly

What is the first step in building a cladogram?

• Calculating the age of each species

• Determining a list of evolutionary characteristics

• Listing all known species

• Identifying the geographical location of species