Chapter 21.2 - Reproductive Isolation

Question 1

Textbook:
What is reproductive isolation?

Answer 1

Reproductive isolation refers to a barrier that prevents two different species or populations from successfully interbreeding and producing fertile offspring.

Question 2

Textbook:
What is prezygotic reproductive isolation?

Answer 2

Prezygotic isolating factors occur before the fertilization of an egg.
Prevent fertilization from taking place.

Question 3

Textbook:
What is post-zygotic isolation?

Answer 3

Isolating factors come into play after fertilization.
Result in the failure of a fertilized egg to develop into a fertile individual.

Question 4

Textbook:
What are the 6 different types of prezygotic isolations?

Answer 4

1. Geographical
2. Ecological
3. Temporal
4. Behavioral
5. Gametic
6. Mechanical/Anatomical

Question 5

Textbook:
What are the 2 different types of post-zygotic isolation?

Answer 5

1. Hybrid inviability
2. Hybrid sterility

Question 6

Textbook:
What is geographic isolation?

Answer 6

Geographic isolation occurs when two populations are separated by geographic barriers such as mountains or bodies of water.

Question 7

Textbook:
What is an example of geographical isolation?

Answer 7

A population of squirrels were separated by the Grand Canyon. Today, they are 2 different species that have different fur colors and eat different foods.

Question 8

Textbook:
What is ecological isolation?

Answer 8

Ecological isolation occurs when 2 populations prefer different habitats.

Question 9

Textbook:
What is an example of ecological isolation?

Answer 9

2 Japanese species of ladybug beetles feed and mate on different types of plants, as their life cycle is associated with their host plants.

Question 10

Textbook:
What is temporal isolation?

Answer 10

Temporal isolation occurs when individuals reproduce at different times.

Question 11

Textbook:
What is an example of temporal isolation?

Answer 11

2 species of crickets are sexually mature during different seasons. One population matures during the spring, while the other during the summer.

Question 12

Textbook:
What is behavioral isolation?

Answer 12

Behavioral isolation occurs when individuals only mate based on rituals, songs or other behaviors

Question 13

Textbook:
What is an example of behavioral isolation?

Answer 13

Some crickets only recognize the chirps of their own species, preventing them from breeding with closely related cricket species.

Question 14

Textbook:
What is gametic isolation?

Answer 14

Gametic isolation occurs when gametes are not able to fuse to form a fertile egg.

Question 15

Textbook:
What is an example of gametic isolation?

Answer 15

Sea urchins have proteins on their surface that allow egg and sperm to merge. Variations in these proteins make it impossible to connect in some species.

Question 16

Textbook:
What is mechanical isolation?

Answer 16

The genitalia of the organisms do not fit/are incompatible.

Question 17

Textbook:
What is an example of mechanical isolation?

Answer 17

There are beetle species that live close together, but their reproductive organs are so different that they cannot mate with each other.

Question 18

Textbook:
What is hybrid inviability?

Answer 18

Hybrid inviability occurs when the embryo forms but does not fully develop.

Question 19

Textbook:
What is an example of hybrid inviability?

Answer 19

The hybrid embryos of sheep and goats, for example, die in the early developmental stages before birth.

Question 20

Textbook:
What is hybrid sterility?

Answer 20

Hybrid sterility occurs when offspring is produced but cannot reproduce (are sterile).

Question 21

Textbook:
What is an example of hybrid sterility?

Answer 21

Because donkeys and horses have different chromosome numbers, proper homologous pairing in meiosis in the mule cannot take place, resulting in the infertility of the mule.