Evo Test 2 - Chapter 4

Front 1

an approach to classifying organisms based upon their evolutionary histories

Back 1

phylogenetic systematics

Front 2

the branching pattern of relatedness among populations as they give rise to multiple descendant populations over evolutionary time

Back 2

phylogeny

Front 3

observable characteristics of organisms

Back 3

traits

Front 4

kinds of traits used for studying phylogeny

Back 4

-anatomical features
-developmental processes
-behavioral patterns
-genetic sequences

Front 5

group of related organisms indicated by a branch tip in a phylogenetic tree

Back 5

taxon

Front 6

taxon related to the groups of interest but that branched off earlier in evolutionary history

Back 6

outgroup

Front 7

taxa derived from same node

Back 7

sister taxa

Front 8

node with more than two branches that represents uncertainty about evolutionary relationships

Back 8

polytomy

Front 9

a taxonomic group consisting of all descendants of the group's most common ancestor and no other members

Back 9

monophyletic group

Front 10

consists of a group of species that share a single common ancestor

Back 10

clade

Front 11

a group of species that does not contain the common ancestor of its members and/or contain all descendants of that common ancestor

Back 11

polyphyletic group

Front 12

a group of species that contains the group's most common ancestor but not all of its descendants

Back 12

paraphyletic group

Front 13

how do polyphyletic groups usually arise?

Back 13

from grouping organisms using analogies rather than homologies

Front 14

a phylogenetic tree in which the root is indicated and thus the direction of time is specified

Back 14

rooted tree
-the root represents the most ancestral common ancestor
-direction indicates passage of time

Front 15

same common ancestor gives character

Back 15

homologies

Front 16

separate evolutional origins but superficially similar due to evolutionary processes such as natural selection

Back 16

analogies

Front 17

occurs when closely related populations or closely related species diverge from one another because natural selection operates differently on each of them

Back 17

divergent evolution

Front 18

when two or more populations or species become more similar to one another because they are exposed to similar selective conditions

Back 18

convergent evolution

Front 19

how to avoid using other traits besides synapomorphies

Back 19

1. pick traits likely to be synapomorphies
2. use large number of characters
3. use outgroup to estimate polarity

Front 20

order of appearance of a trait in evolutionary time

Back 20

polarity

Front 21

how does using an out group work?

Back 21

helps estimate polarity, can infer that ancestral trait will be shared by outgroup and some members group of interest

Front 22

an organism is unable to return to its previous stages already realized in the ranks of its ancestors

Back 22

Dollo's Law

Front 23

a trait so fundamental that homology of these processes occurs across a very diverse group of species

Back 23

deep homology

Front 24

traits that have no known current function but appear to have been important in the evolutionary past

Back 24

vestigial trait

Front 25

why do vestigial traits exist?

Back 25

1. not costly to organism
2. some natural selection occurs against it - eventual loss
3. trait has unidentified function
-strong test of Darwin's theory of common ancestry
will not be present in groups that diverged before the evolution of the vestigial trait