Unit 3-Lesson 6

Question 1

What is speciation/macroevolution?

Answer 1

Speciation: the formation of a new species from an existing species (AKA macroevolution)

Question 2

What is microevolution?

Answer 2

Microevolution: change within the frequency of alleles in a population

Question 3

Why does speciation happen?

Answer 3

When two populations have become reproductively isolated over time, there is “No gene flow between them”

Question 4

What are the two type of reproductive isolating mechanism?

Answer 4

• Pre-Zygotic
• Post-Zygotic

Question 5

What are the 5 pre-zygotic isolating mechanisms?

Answer 5

• Behavioural
• Habitat
• Temporal
• Mechanic
• Gametic

Question 6

What is behavioural isolating mechanisms?

Answer 6

Species have a specific signal or behaviour that prevents closely related species from interbreeding

Question 7

What is habitat isolating mechanism?

Answer 7

Two species live in the same area but different habitats, they rarely encounter and interact with one another

Question 8

What is temporal isolating mechanism?

Answer 8

• Temporal conditions refers to time of day, year and season
• Some organisms mate at different times which limits their interaction
• Very common in flower species

Question 9

What is mechanical isolating mechanism?

Answer 9

• Some species are anatomically incompatible and unable to fertilize
  
  • Ex. The genital in insects like a lock and key model

Question 10

What is gametic isolating mechanism?

Answer 10

• Occurs when a species gametes (egg and sperm) are not able to fuse to form a zygote
  
  • Ex. Sperm is unable to survive within female reproductive tract

Question 11

What are the 3 post-zygotic mechanism?

Answer 11

• Hybrid Inviability
• Hybrid Sterility
• Hybrid Breakdown

Question 12

What is pre-zygotic isolating mechanism?

Answer 12

Species are not able to mate or when eggs cannot be fertilized (AKA Pre-fertilization Barries)

Question 12

What is post-zygotic mechanism?

Answer 12

Sperm and egg meet, but zygote cannot develop into a viable offspring

Question 13

What is Hybrid inviability?

Answer 13

• When genetic information is not compatible between species
• Zygote does not undergo mitosis, and zygote cannot develop further
  
  • E.g. hybrid embryo between sheep and goats die before birth

Question 14

What is Hybrid Sterility?

Answer 14

• Two species can mate and produce hybrid offspring (ie. Mule + donkey)
• However, the hybrid offspring is sterile
• Meiosis fails to produce normal gametes in the hybrid offspring

Question 15

What is hybrid breakdown?

Answer 15

• Two organisms are able to mate and produce viable and fertile offspring
• However, when the hybrid species mate, (2nd generation) their offspring are weak and sterile

Question 16

What are the two types of speciation?

Answer 16

• Sympatric Speciation
• Allopatric speciation

Question 17

What is sympatric speciation?

Answer 17

• Populations in same geographical area become reproductively isolated
• More common in plants than animals
• Chromosomal changes in plants or non-random mating in animal alters gene flow
• The result is reproductive incompatibility without geographical isolation

Question 18

What is Allopatric Speciation?

Answer 18

• Occurs when populations are separated by a geographical barrier and diverge genetically
• Gene flow is interrupted
• Separation can occur due to river, water level change, geological remodelling

Question 19

What is adaptive radiation?

Answer 19

• Type of allopatric speciation
• Diversification of a common ancestral species into a variety of differently adapted species

Question 20

What is Divergent evolution?

Answer 20

Species that were similar to the ancestral species diverge and become increasingly distinct

Question 21

What is Convergent evolution?

Answer 21

Similar traits arise because different species have independently adapted to similar environmental conditions