Origin of species and Macroevolution

Question 1

what level does macroevolution occur?

Answer 1

at or below the species level

Question 2

what is speciation?

Answer 2

the process of species formation

Question 3

what are species?

Answer 3

a group of organisms that maintains a distinctive set of attributes in nature.

Question 4

what are subspecies?

Answer 4

groups of the same species that have somewhat different traits but not different enough to be called a separate species

Question 5

what are ecotypes?

Answer 5

bacterial species, genetically distinct population adapted to local environment

Question 6

list the most commonly used characteristics used to identify species

Answer 6

morphological traits, ability to interbreed, molecular features, ecological factors and evolutionary relationships.

Question 7

what is a biological species?

Answer 7

A biological species is a group of interbreeding (or potentially interbreeding) individuals, that is reproductively isolated from other such groups

Question 8

list problems with the biological species concept

Answer 8

• May be difficult to determine in nature
• Can interbreed and yet do not
• Does not apply to asexual organisms
• Cannot be applied to extinct organisms

Question 9

list the molecular traits that can compare features to identify similarities and differences among different populations.

Answer 9

• D N A sequences within genes
• Gene order along chromosomes
• Chromosome structure
• Chromosome number

Question 10

what are ecological factors?

Answer 10

variety of factors related to an organism’s habitat can be used to distinguish one species from another

Question 11

what do evolutionary trees describe?

Answer 11

relationships between ancestral species and modern species (fossil records and DNA sequence)

Question 12

interspecific mating

Answer 12

interbreeding between different species

Question 13

what do reproductive isolating mechanisms do?

Answer 13

prevent interbreeding between different species and is a consequence of genetic changes as species adapt to its environment

Question 14

what is interspecies hybrid?

Answer 14

when two different species are able to produce offspring (usually with reduced fitness)

Question 15

Reproductive isolating mechanisms prevent?

Answer 15

gene pools mixing

Question 16

Prezygotic isolating mechanisms occur ___?___ zygote formation

Answer 16

before

Question 17

Postzygotic isolating mechanisms occur ___?___ zygote formation

Answer 17

after

Question 18

list the prezygotic isolating mechanisms

Answer 18

1. Ecological isolation from habitats
2. Temporal isolation from mating timing (reproduce at different times of the day or year)
3. Behavioural isolation from mating signals, sexual selection
4. Mechanical isolation from reproductive structures (size or incompatible genitalia prevents mating)
5. Gametic isolation from gamete incompatibility (gametes fail to unite successfully)

Question 19

what do prezygotic and postzygotic isolating mechanisms do?

Answer 19

prezygotic prevents the formation of zygotes while postzygotic block development of viable, fertile individuals

Question 20

list the postzygotic isolating mechanisms

Answer 20

1. Hybrid inviability: Species hybrids not
   surviving
2. Hybrid sterility: Species hybrids not
   producing functional gametes
3. Hybrid breakdown: Reduced fitness of F2

Question 21

what is the underlying cause of speciation?

Answer 21

accumulation of genetic changes that ultimately promote enough differences so that we judge a population to constitute a unique species

Question 22

what is cladogenesis?

Answer 22

division of a species into two or more species, requires gene flow between populations to be interrupted

Question 23

what is allopatric speciation?

Answer 23

it is the most prevalent method of cladogenesis and occurs when some members of a species become geographically separated.

Question 24

what is species cluster?

Answer 24

group of closely related species

Question 25

what is sympatric speciation?

Answer 25

Occurs when members of a species that are within the same range diverge into two or more different species even though there are no physical barriers to interbreeding

Question 26

list the sympatric speciation mechanisms

Answer 26

1. Polyploidy (organism has more than two sets of chromosomes) 2. Hybrid speciation 3. Adaptation to local environments 4. Sexual selection

Question 27

In the absence of gene flow, geographically separated populations inevitably accumulate genetic differences through the action of?

Answer 27

mutation, genetic drift, and natural selection

Question 28

list the reproductive isolations

Answer 28

* Postzygotic reproductive isolation * Prezygotic reproductive isolation * Sexual selection

Question 29

what are autopolyploids?

Answer 29

increased number of sets of chromosomes from the same parental species

Question 30

Allopolypoids

Answer 30

contain chromosomes from two or more different species

Question 31

formation of an allopolyploid can abruptly lead to?

Answer 31

reproductive isolation and speciation

Question 32

Gradualism

Answer 32

Each new species evolves continuously over long spans of time

Question 33

Punctuated equilibrium

Answer 33

tempo more sporadic, species in equilibrium for long periods and then short rapid bursts of changes

Question 34

genes that play a role in development may influence?

Answer 34

1. Cell division 2. Cell migration 3. Cell differentiation 4. Cell death (apoptosis)

Question 35

what does BMP4 do?

Answer 35

causes cells to undergo apoptosis and die

Question 36

what does gremlin do?

Answer 36

inhibits the function of BMP4 and allows cell to survive

Question 37

what is heterochrony?

Answer 37

evolutionary changes in the rate or timing of developmental events

Question 38

how does genetic variation influence morphology?

Answer 38

by controlling relative growth rates of different parts of the body during development.