Lecture 4

Question 1

Allopatric speciation

Answer 1

speciation that occurs as the result of introducing a geographical barrier

Question 2

Allopatric speciation can occur as the result of

Answer 2

• introduction of mountain range which gradually splits two population of organisms
• the formation of a land bring diving marine populations in two

Question 3

Sympatric speciation

Answer 3

new species arises within the same geographical area as the parent species

Question 4

3 main ways sympatric speciation occur

Answer 4

• polyploidy
• habitat differentiation
• sexual selection

Question 5

Polyploidy

Answer 5

accidents during cell division result in extra sets of chromosomes

Question 6

Polyploidy is defined as..

Answer 6

a cell that has greater than 2 complete chromosome sets

Question 7

Habitat differentiation

Answer 7

morns to different likely to be the mechanism of speciation in animals, adaptions to different habitats in the same geographical area can lead to speciation because matin in between the two groups would be rare

Question 8

Sexual selection

Answer 8

choosing mates based on some physical characteristic such as colour

Question 9

2 mechanisms of speciation

Answer 9

• allopatric speciation

- sympatric speciation

Question 10

Hybrid zones

Answer 10

are regions in which members of different species meet and mate producing some hybrid offspring

Question 11

3 possible outcomes for the hybrid zone over time

Answer 11

• reinforcement
• fusion
• stability

Question 12

Reinforcement

Answer 12

when hybrids are less fit than both parent species, expect that natural selection would strengthen reproduce barriers, which prevents formation of unfit hybrids

Question 13

Fusion

Answer 13

reproductive barriers between two species are not strong so gene flow may occur in the hybrid zone reversing speciation

Question 14

Stability

Answer 14

hybrid zones are stable and continue to reproduce, some gene flow may occur between populations, each species maintains its own integrity

Question 15

Adaptive radiation

Answer 15

evolution of many diverse species from one common ancestor, these adaptations of these species allow them to fill new habitats or roles in their community

Question 16

Adaptive radiation is linked to new opportunity..

Answer 16

• no competitors
• new habitats and food sources
• sometimes new structures evolve

Question 17

2 types of rates of speciation

Answer 17

• punctuated equilibrium

- gradualism model

Question 18

Punctuated equilibrium

Answer 18

long periods wit little or no change, equilibrium, punctuated by abrupt epodes of speciation

Question 19

Gradualism

Answer 19

species that have diverged gradually over long periods of time. differences gradually evolve in a population as they become better adapted to their new environment

Question 20

Macroevolution

Answer 20

major changes recorded in the history of life over large periods of time

Question 21

The earth is estimated to be how old

Answer 21

4.6 billion years

Question 22

How long ago was the big bang

Answer 22

10-20 billion years ago

Question 23

Earth probably began as ..

Answer 23

molten mass

Question 24

Conditions of early earths atmosphere

Answer 24

• nitrogen, oxides, carbon dioxide, methane, ammonia, hydrogen sulfide, and hydrogen present
• as earth cooled the water vapour condensed into oceans and H gas escaped into space
• very intense light, lighting, and volcanic activity
• NO OXYGEN

Question 25

Earliest evidence of life on Earth is from fossils such as stromatolite which are ______ old

Answer 25

3.5 billion years

Question 26

It is thought that life in an even simpler form may have arose as early as..

Answer 26

3.9 billion years ago

Question 27

Early life simple cells could have formed via the following 4 stages

Answer 27

- abiotic synthesis of small organic molecules such as amino acids and nucleotides - joining of these small molecules into macromolecules (DNA) - packaging of these macromolecules into "protobionts" - the origin of self replicating molecules which eventually made inheritance possible

Question 28

Protobionts

Answer 28

which are droplets surrounded by membranes that maintain an internal chemistry different than that of the external surroundings

Question 29

Stanley miller was the first to...

Answer 29

show that amino acids and other organic molecule could be formed under then conditions of early earth

Question 30

Organic molecules cannot be synthesized spontaneously because..

Answer 30

of the presence of atmospheric oxygen which oxides chemical bonds

Question 31

Stanley miller experiments

Answer 31

flask of warm water represented the early sea, water was heated so that some evaporated and moved into a second flask to stimulate the early earth. atmosphere contained H, H2o vapour, methane, ammonia, electrode discharged shocks into the flask to stimulate lighting, a condenser cooled the atmosphere, raining water and any dissolved articles back into the initial flask, after 1 week found a variety of organic compounds (amino acids)