Phylogenetics 1 - 2

Question 1

what is a phylogeny

Answer 1

a visual representation of the evolutionary history of populations, genes, or species

Question 2

what does monophyletic mean

Answer 2

describes a group of organisms that form a clade, that is the group is made up of an organism and all of its descendants

Question 3

what does polyphyletic mean

Answer 3

describes a taxonomic group that does not share an immediate common ancestor and therefore does not form a clade

Question 4

what is a clade

Answer 4

an organism and all its descendants

Question 5

what is a synapomorphy

Answer 5

a derived form of a trait that is shared by a group of related species (that is, one that evolved in the immediate common ancestor of the group and was inherited by all its descendants)

Question 6

what is a symplesiomorphy

Answer 6

the character shared by the two or more taxa occurs in their earliest common ancestor.

Question 7

when was the first life

Answer 7

~3.7 bya

Question 8

what is the age of the earth

Answer 8

~4.6 bya

Question 9

when was the cambrian explosion

Answer 9

~540 mya

Question 10

when was the end of the paleozoia

Answer 10

~250 mya

Question 11

when was the end of the mesozoic

Answer 11

~65 mya

Question 12

when was the anthropocene

Answer 12

~10 kya

Question 13

what is a branch

Answer 13

lineage evolving through time between successive speciation events

Question 14

what is a node

Answer 14

point in a phylogeny where a lineage splits (a speciation event)

Question 15

what is an internal node

Answer 15

located within the phylogeny representing ancestral populations/species that have long since disappeared

Question 16

what is a tip

Answer 16

terminal end of an evolutionary tree, representing species, molecules, or populations being compared

Question 17

what is a cladogram

Answer 17

when a phylogenetic tree shows only the relationship among species

Question 18

what is a paraphyletic clade

Answer 18

an ancestor and a group of taxa but it is not monophyletic because some of the descendants are missing. you can swivel branches at nodes

Question 19

what is convergent evolution

Answer 19

the independent origin of similar traits in separate evolutionary lineages

Question 20

what is an outgroup

Answer 20

group of organisms (for example, a species) that is outside of the monophyletic group being considered

Question 21

what is homoplasy

Answer 21

describes a character state similarity not due to shared descent. for example, produced by convergent evolution or evolutionary reversal

Question 22

what is evolutionary reversal (character reversal)

Answer 22

describes the reversion of a derived character state to a form resembling its ancestral state

Question 23

what does vestigial mean

Answer 23

structures that have no apparent function and appear to be residual parts from a past ancestor

Question 24

what is a character

Answer 24

any observable feature or trait of an organism that can be inherited

Question 25

character state

Answer 25

value of the character, ex. blue eyes, brown hair

Question 26

ancestral state

Answer 26

character state present in a lineage immediately before a character state change

Question 27

derived state

Answer 27

character state of a trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants

Question 28

taxon (taxa)

Answer 28

group of organisms that a taxonomist judges to be a cohesive taxonomic unit, such as a species or order