Evolution

Question 1

Homology/Homologous

Answer 1

sharing traits via a common ancestor

Question 2

Divergence/decent with modification

Answer 2

over time, similarities between daughter lineages decrease

Question 3

Tip

Answer 3

end points (modern or extinct)

Question 4

Nodes

Answer 4

hypothetical common ancestors of species that descended from that branch point

Question 5

Root

Answer 5

the branch leading to the common ancestor of all the taxa in the tree

Question 6

Clade

Answer 6

a group of species or genes that include all descendents of an ancestral species or gene

Question 7

monophyletic

Answer 7

group/clade where all species share a common ancestor

Question 8

paraphyletic

Answer 8

group where all species share a common ancestor, but some species are excluded from the group

Question 9

polyphyletic

Answer 9

grouping of lineages more closely related to other species not in the group than they are to each other

Question 10

phylogram

Answer 10

length of branches can indicate the amount of evolutionary change

Question 11

dendrogram

Answer 11

tips of the tree are kept the same length from the root and can be used to represent evolutionary time since divergence

Question 12

polytomy

Answer 12

a phylogenetic tree can have more than two branches from a single node (can show ambiguity)

Question 13

outgroup

Answer 13

taxonomic unit that branched off in ecolution prior to the common ancestor of all individuals in the ingroup (used to root trees)

Question 14

bootstraping

Answer 14

analyzes a tree by resampling with replacement (common for nodes)

Question 15

jackknifing

Answer 15

analyzes a tree by resampling without replacement

Question 16

ortholog

Answer 16

homologous genes in a different species that arose from a single gene in the last common ancestor of these species

Question 17

paralog

Answer 17

homologous genes in the same species that are related by duplication of an ancestral gene

Question 18

gene duplication can lead to

Answer 18

1) non functionalization
2) conservation
3) neofunctionalization
4) specialization
5) subfunctionalization

Question 19

How many exons usually encode Ig domains?

Answer 19

two

Question 20

purifying selection

Answer 20

aspect of natural selection that reduces genetic variation and preserves DNA and protein sequences

Question 21

evidence of purifying selection

Answer 21

dN/dS < 1

Question 22

neutral selection

Answer 22

dN/dS = 1

Question 23

positive/darwinian selection

Answer 23

dN/dS > 1

Question 24

selective sweeps/hitchhiking

Answer 24

reduce variation in regions of the chromosome adjacent to selected sequence

Question 25

evolution

Answer 25

genetic change in a group of organisms

Question 26

steps of evolution

Answer 26

1) genetic variation arises through mutation and recombination
2) change in frequencies of genetic variants

Question 27

types of evolution

Answer 27

anagenesis - evolution in a single lineage over time
cladogenesis - splitting of one lineage into two, speciation

Question 28

molecular data

Answer 28

1) genetic
2) can be used with all organisms
3) can be applied to huge amount of genetic variation
4) quantifiable
5) provides info about the process of evolution

Question 29

neutral mutation hypothesis

Answer 29

when selection is important there won’t be a lot of genetic variation

Question 30

balancing selection

Answer 30

selection that maintains variation
-overdominance - both homozygotes have much greater fitness than heterzygote
-sickle cell vs malaria

Question 31

species

Answer 31

different types of living organisms
-evolutionary independent group

Question 32

biological species concept

Answer 32

species is a group of individuals that can interbreed with each other, but are reproductively isolated from members of other species

Question 33

morphospecies concept

Answer 33

only phenotype

Question 34

phylogenetic species concept

Answer 34

smallest recognizable group that has a unique evolutionary history

Question 35

temporal isolation

Answer 35

reproduction at different times of year

Question 36

ecological isolation

Answer 36

don’t encounter each other/different habitats

Question 37

behavioral isolation

Answer 37

differences in behavior prevent breeding, mating calls

Question 38

mechanical isolation

Answer 38

anatomical differences prevent copulation

Question 39

gametic isolation

Answer 39

can mate but gametes don’t for zygote

Question 40

speciation

Answer 40

process by which new species arise

Question 41

allopatric speciation

Answer 41

a geographic barrier splits population

Question 42

reinforcement

Answer 42

postzygotic isolation mechanisms encourage the development of prezygotic isolation mechanisms

Question 43

sympatric speciation

Answer 43

speciation without external barrier

Question 44

difficulties with sympatric

Answer 44

-need genetic differentiation to occur
-nonrandom association of genes can promote speciation but recombination usually breaks up nonrandom association

Question 45

distance approach

Answer 45

based on overall similarity

Question 46

maximum parsimony

Answer 46

fewest evolutionary changes since last common ancestor

Question 47

maximum likelihood/bayesian methods

Answer 47

which phylogeny maximizes probability of obtaining organism’s characteristics

Question 48

exon shuffling

Answer 48

exons of different genes are exchanged creating genes that are mosaics of other genes

Question 49

multigene families

Answer 49

a group of genes that share a common ancestor gene and are created from gene duplication and differentiation

Question 50

whole genome duplication

Answer 50

can happen through polyploidy
-2R hypothesis - early vertebrates went through two rounds of duplication