Taxonomy 3

Question 1

What are the main methods of classification?

Answer 1

1. Phenetics
2. Cladistics
3. Orthodox approach

Question 2

What is phenetic classification ?

Answer 2

Groups of organisms based of overall phenotypic similarity.
All characters given equal weighting
Doesn’t consider evolutionary relationships

Question 3

What are homologous characters ?

Answer 3

Traits that are inherited from a common ancestor

Question 4

What are analogous characters ?

Answer 4

Traits that serve similar functions but do not share a common ancestor
The evolved independently in different lineages due to convergent evolution

Question 5

What is cladistics ?

Answer 5

Groups of organisms based on evolutionary ancestry using shared derived characteristics
Produces cladograms or phylogenetic trees
Based on shared, derived homologous characters
Paraphyletic and polyphyletic taxa are invalid

Question 6

What is monophyletic ?

Answer 6

If a group includes a common ancestor and all of its descendants

Question 7

What is polyphyletic ?

Answer 7

If a group does not include the common ancestor of all its members

Question 8

What is paraphyly ?

Answer 8

Includes a common ancestor and some but not all of its descents

Question 9

How are monophyletic taxa recognised ?

Answer 9

1. Traits provide different kinds of info on genealogy
2. Infer whether a change is a trait occurred early or late in ancestry
3. Groupings should be based on only new trait states arising in the nearest common ancestor

Question 10

Why do taxa resemble one another ?

Answer 10

1. The character arose early on in the ancestry of the taxa, before the occurrence of the newest common ancestor
2. The character originated in the nearest common ancestor= shared derived character
3. The character originated independently, by convergence

Question 11

What is homoplasy ?

Answer 11

Similarity due to convergence

Question 12

What is character polarity ?

Answer 12

Helps to determine the ancestral or derived state of a character trait

Question 13

What are the methods for assessing character polarity ?

Answer 13

1. Outgroup comparison
2. Embryology
3. Fossil record

Question 14

What are the problems with cladistics ?

Answer 14

1. Considers only cladogenesis
2. Ignores anagenesis
3. Sister- taxa are therefore given the same rank

Question 15

What is orthodox classification ?

Answer 15

Based on both genealogy (cladogenesis) and divergence
Weighting of homologous characters
Classifications based on molecular genetic data