PHYLOGENETICS L22

Question 1

taxonomy

Answer 1

• naming
• describing
• classifying
• used Linnaean system
• biological nomenclature

Question 2

phylogeny

Answer 2

• evolutionary history of species or groups

Question 3

cladistics

Answer 3

• a method of systematics based on phylogenetics

- each clade nested within larger groups

Question 4

branch point

Answer 4

• represents divergence of 2 lineages from common ancestor
• represents dichotomies - 2 way branch points
• branches can be rotated about nodes, does not change relationship

Question 5

sister taxa

Answer 5

• groups of organisms that share an immediate common ancestor
• each others closest relatives

Question 6

basal taxon

Answer 6

• lineage that diverges early in history of group
• 1st to diverge from common ancestor
• outgroup

Question 7

ingroup

Answer 7

• group that you are studying

- everything else on tree

Question 8

polytomy

Answer 8

• branch point with more than 2 groups

- indicates unclear evolutionary relationship

Question 9

monophyletic group

Answer 9

• a common ancestor and ALL of its descendants

Question 10

paraphyletic group

Answer 10

• a common ancestor and SOME of its descendants

Question 11

polyphyletic group

Answer 11

• distantly related species, but not most recent common ancestor

Question 12

ancestral trait

Answer 12

• trait present in outgroup

Question 13

derived trait

Answer 13

• trait present in ingroup, absent from outgroup

Question 14

shared derived trait

Answer 14

• derived trait present in all members of ingroup

Question 15

homologous structures

Answer 15

• similar due to common ancestry

- useful for cladistics

Question 16

analogous structures

Answer 16

• similar due to convergent evolution
• similar selective pressures – similar character states
• NOT useful for cladistics

Question 17

evaluating molecular homology

Answer 17

sequence genome(s) – align sequences – evaluate differences –

• • few differences – closely related
• • many differences – distantly related