6a. Phylogenetics

Question 1

Orthologs

Answer 1

genes in different species evolved from a common ancestral gene

Question 2

Paralogs

Answer 2

gene copies created by a duplication event within the same genome

Question 3

Monophyletic group

Answer 3

descendants from a common ancestor

Question 4

Polyphyletic group

Answer 4

lacks a direct common ancestor: characters called homoplasies  due to convergent evolution

Question 5

Paraphyletic group

Answer 5

consists of the group’s last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—monophyletic subgroups

Question 6

Homoplasie

Answer 6

analogous structures/traits originating from convergent evolution; independent evolutionary events

Question 7

Difference between homology and analogy

Answer 7

Homology involves the study of organs that have evolved from same origin or from common ancestor but have different functions. For example, wings of bat and hands of humans.
Analogy involves the study of organs that are evolved from different ancestors but perform a similar function.

Question 8

Autapomorphy

Answer 8

a trait that is unique to a particular taxon

Question 9

Apomorphy (systematics)

Answer 9

a relatively new trait shared by a few taxons

Question 10

Synapomorphy (cladistics)

Answer 10

a derived trait that is shared by two or more taxa of shared ancestry

Question 11

Plesiomorphic character

Answer 11

a primitive ancestral character

Question 12

Symplesiomorphic character

Answer 12

shared ancestral character (a shared plesiomorphy), shared by two or more taxa, but also with other taxa linked earlier in the clade

Question 13

Morphological characters (anatomy of skeleton, skin morphology, etc) PROS/CONS

Answer 13

• Pros: low level of homoplasy (conversion/reversion); use of fossil record
• Cons: labor intensive, difficult to assess, expert work

Question 14

• Molecular characters (DNA-base sequences, Protein-amino acid sequences, structural genome features) PROS/CONS

Answer 14

• Pros: large datasets, easy to retrieve in short time frame more unbiased.
• Cons: considerable amount of homoplasy

Question 15

properties of the different methods

• Neigbor joining
• maximum likelihood
• maximum Parsimony

Answer 15

• Neigbor joining; includes mutations rates differences, fast
• Maximum likelihood; also includes the different freq. at which different mutations arise
• Maximum persimony; The smallest number of steps is probably the right one

Question 16

Horizontal gene transfer (HGT) or lateral gene transfer (LGT)

Answer 16

is the movement of genetic material between unicellular and/or multicellular organisms other than by the (“vertical”) transmission of DNA from parent to offspring (reproduction)