Evolution Chapter 9.2

Question 1

What is speciation?

Answer 1

The formation of a new species from an existing species as some members of a sexually reproducing population change that they cannot produce offspring with members of the same population

Question 2

How can two populations become reproductively isolated?

Answer 2

When there is little or no gene flow between them

Question 3

What are the two types of reproductive isolating mechanisms and what do they do?

Answer 3

• Pre-zygotic and post-zygotic

- Prevent gene flow between populations

Question 4

What is pre-zytotic isolating mechanisms?

Answer 4

• Prevent mating/fertilization of eggs if individuals from different species try to mate

Question 5

What are the three types of pre-zygotic isolating mechanisms?

Answer 5

Behavioural, habitat, temporal, mechanical, gametic isolating mechanisms

Question 6

What is behavioural isolating mechanisms?

Answer 6

Species signals/behviours that are distinct to that species prevent interbreeding with closely related species

Question 7

What is habitat isolating mechanisms?

Answer 7

Two species live in general region but in different habitats

Question 8

What is temporal isolating mechanisms?

Answer 8

Many species are kept separate by timing barriers (mate different times of day)

Question 9

What is mechanical isolating mechanisms?

Answer 9

Closely related species cannot mate because they are anatomically incompatible

Question 10

What is post-zygotic mechanism?

Answer 10

Two different species produces zygote and this barrier prevents hybrid zygotes from developing into fertile individuals

Question 11

What are the types of post-zygotic mechanisms that prevent zygotes from developing into fertile individuals?

Answer 11

Hybrid Inviability, Hybrid Sterility, Hybrid Breakdown

SIB

Question 12

What is hybrid inviability?

Answer 12

• Gametic incompatibility of interbred species may stop development of the hybrid zygote
• Prevents normal mitosis
  Ex: zygote of goat and sheep die before birth

Question 13

What is hybrid sterility?

Answer 13

• Two species mate to produce hybrid offspring

- Reproductive barrier still exists

Question 14

What are the types of speciation?

Answer 14

Sympatric and Allopatric Speciation

Question 15

What is sympatric speciation?

Answer 15

Populations live in the same geographical area but become reproductively isolated

Question 16

In sympatric speciation, what alters gene flow?

Answer 16

1. Chromosomal changes (plants)

2. Non - random mating (animals)

Question 17

What is polyploidy?

Answer 17

• Cell division error, extra set of chromosomes

- Can lead to speciation

Question 18

What is allopatric speciation?

Answer 18

When a population is split into two or more isolated groups by a geographical barrier

Question 19

What happens during allopatric speciation?

Answer 19

The gene pool of the split population becomes so distinct that they can no longer mate

Question 20

What is an ecological niche?

Answer 20

The ecological role and physical distribution of a species in its environment