Evolution 5.4 Cladistics

Question 1

What is a clade?

Answer 1

A group of organism that includes all of the evolutionary descendants of a common ancestor

Question 2

What is a cladogram?

Answer 2

A tree diagram that shows the most probable sequence of divergences in a clade

Question 3

According to this diagram are reptiles a clade?

Answer 3

No reptiles are not a clade because they do not include all descendant of a common ancestor.

Question 4

How do you identify members of a clade?

Answer 4

Evidence for which species are part of a clade can be obtained form the base sequence of a gene or the corresponding amini acid sequence.

Question 5

What is a molecular clock?

Answer 5

Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species.

Changes in the DNA base sequence for a specific gene expected to occur gradually, at a constant rate

Question 6

What is an analogous trait?

Answer 6

An analogous trait is a characteristic that two organisms share due to convergent evolution, not common ancestry

Question 7

What is a homologous trait?

Answer 7

A homologous trait is a characteristic that two organisms share due to common ancestry

Question 8

How are cladograms and reclassification related?

Answer 8

Evidence from claditics has shown that classifications of some groups based on structure did not corespond with the evolutionairy origins of a group of species

Question 9

What is falsification?

Answer 9

Falsification of theories with one theory being susperseded by another plant families have been reclassified as a result of evidence from cladistics.

Question 10

What is an example of a plant taxon that has been reclassified in light of new evidence?

Answer 10

Figwort family is an example of a plant taxon that has been reclassified in light of new evidence from DNA analysis and cladistics