Evolutionary Genetics

Question 1

Theodosius Dobzhansky quote

Answer 1

“Nothing in biology makes sense except in light of evolution”

Question 2

Biological Evolution

Answer 2

genetic change in a group of organisms

two step process
two different types

Question 3

types of evolution

Answer 3

anagenesis
cladogenesis

Question 4

anagenesis

Answer 4

change within an evolutionary lineage (same species)

Question 5

cladogenesis

Answer 5

breaking into two species

Question 6

molecular variation

Answer 6

DNA sequence variation
protein variation

Question 7

how did early geneticists determine different species/traits?

Answer 7

looking only at phenotypes

Question 8

molecular variation

Answer 8

• molecular data are genetic
• can be used with all organisms
• can be applied to many phenotypes (huge amount of genetic variation)
• all organisms can be compared with the use of some molecular data
• quantifiable
• provide some information about the process of evolution
• the database of molecular information is large and growing

Question 9

how do we measure genetic variation?

Answer 9

• proportion of polymorphic loci (how many different)
• expected heterozygosity

Question 10

how can we explain protein variation?

Answer 10

• neutral mutation hypothesis
• balance hypothesis

Question 11

neutral mutation hypothesis

Answer 11

individuals with different molecular variants of the protein have EQUAL FITNESS

Question 12

balance hypothesis

Answer 12

genetic variation in natural populations is maintained by selecting that which has variance, maintaining BOTH

Question 13

Biological species concept

Ernst Mayer (1942)

Answer 13

organisms that are capable of breeding with one another but are reproductively isolated from the members of other species

Question 14

reproductive isolating

Answer 14

• cannot mate within the species –> speciation, creation of a different species

Question 15

prezygotic barriers to reproduction

Answer 15

egg and sperm, before the zygote forms
- ecological, temporal, mechanical, behavioral, gametic (gametes cannot combine)

Question 16

postzygotic barriers to reproduction

Answer 16

after zygote has formed
- hybrid inviability (does not survive to reproductive age)
- hybrid sterility (hybrid is sterile)
- hybrid breakdown (F1 hybrids are viable and sterile, F2 is inviable/sterile, species cannot form)

Question 17

speciation

Answer 17

allopatric
sympatric
through polyploidy

Question 18

allopatric speciation

Answer 18

geographic barrier (mountain, river, etc.) population split, no gene flow/migration between populations, evolve separately and be unable to reproduce after separation, forming new species

Question 19

sympatric speciation

Answer 19

there is NO geographic barrier, reproductive isolation mechanisms evolve withini a single interbreeding population

Question 20

speciation polyploidy

Answer 20

polyploidy: you get a whole new set of chromosomes
- causes speciation, can happen within a single individual

Question 21

phylogeny

Answer 21

the evolutionary relationships among a group of organisms
phylogenetic tree
branches can be the same (nodes)

Question 22

the alignment of homologous sequences

Answer 22

phylogenetic trees are often constructed from DNA sequence data