Biological Species Concept

Question 1

According to the biological species concept, what defines a species?

Answer 1

A species is defined as a group of organisms that can potentially interbreed, or mate, with one another to produce viable, fertile offspring.

Question 2

What is the key criterion for identifying members of the same species according to the biological species concept?

Answer 2

The key criterion is the potential to interbreed and produce viable, fertile offspring.

Question 3

How does the biological species concept account for the geographical separation of members of the same species?

Answer 3

The concept acknowledges that members of the same species may not necessarily interact or be part of the same interbreeding group in real life. For example, a dog in Australia and a dog in Africa could still potentially interbreed if they were to meet.

Question 4

According to the biological species concept, what determines whether a group of organisms is considered a single species?

Answer 4

In order to be considered a single species according to the biological species concept, a group of organisms must produce healthy, fertile offspring when they interbreed.

Question 5

Why are horses and donkeys considered separate species despite being able to produce hybrid offspring like mules?

Answer 5

Horses and donkeys are considered separate species because their hybrid offspring, such as mules, are sterile and cannot reproduce, which is a key criterion for defining a species according to the biological species concept.

Question 6

What are the mechanisms that prevent successful interbreeding between different species called?

Answer 6

mechanisms of reproductive isolation.

Question 7

What are the two categories of barriers based on when they act, according to the text?

Answer 7

The barriers are split into two categories: prezygotic barriers, which act before fertilization, and postzygotic barriers, which act after fertilization.

Question 8

What is the hybrid offspring of a female horse and a male donkey called?

Answer 8

The hybrid offspring of a female horse and a male donkey is called a mule

Question 9

Why are mules not classified as a distinct species despite being a hybrid of horses and donkeys?

Answer 9

Mules are not classified as a distinct species because they are sterile and cannot reproduce, which is a key criterion for defining a species according to the biological species concept.

Question 10

What does the biological species concept use to determine whether organisms are of the same species?

Answer 10

The biological species concept uses the ability of organisms to interbreed and produce fertile offspring as the criterion for determining whether they are of the same species.

Question 11

What are the two categories of barriers preventing successful interbreeding between different species?

Answer 11

The two categories of barriers are prezygotic barriers, which act before fertilization, and postzygotic barriers, which act after fertilization.

Question 12

What are pre-zygotic isolation mechanisms, and what do they prevent?

Answer 12

Pre-zygotic isolation mechanisms prevent fertilization and zygote formation by preventing potential mates from coming into contact with each other.

Question 13

What is an example of geographic or ecological or habitat isolation?

Answer 13

Two cricket species prefer to live in different environments (sandy soil in disturbed areas vs. loamy, natural soil at the edges of forests), which contributes to their reproductive isolation.

Question 14

What is an example of temporal or seasonal isolation?

Answer 14

Two frog species are reproductively isolated because one species reproduces earlier in the year than the other species.

Question 15

What is behavioral isolation, and how does it contribute to reproductive isolation?

Answer 15

Behavioral isolation occurs when patterns of courtship are different, preventing successful mating. An example is the slight differences in the songs sung by males of two grasshopper species, attracting females of their own species only.

Question 16

What is an example of mechanical isolation?

Answer 16

The male reproductive organs of related species of damselfly have distinctive shapes, preventing successful interbreeding.

Question 17

What is gametic isolation, and how does it contribute to reproductive isolation?

Answer 17

Gametic isolation occurs due to incompatibilities between egg and sperm, preventing fertilization. An example is coral species releasing eggs and sperm into the water en masse for fertilization, but gamete incompatibility prevents certain cross-species hybrids from forming.

Question 18

What is hybrid inviability, and what does it result in?

Answer 18

Hybrid inviability occurs when a fertilized egg fails to develop past the early embryonic stages, resulting in nonviable offspring.

Question 19

What is hybrid sterility, and what causes it?

Answer 19

Hybrid sterility happens when hybrids are sterile due to abnormal development of gonads or abnormal segregation of chromosomes during meiosis.

Question 20

What is hybrid breakdown, and how does it manifest?

Answer 20

Hybrid breakdown occurs when F1 hybrids are normal, vigorous, and viable, but the F2 generation contains many weak or sterile individuals, leading to decreased viability and fertility in subsequent generations.

Question 21

What is an example of hybrid inviability?

Answer 21

An example of hybrid inviability is when a fertilized egg fails to develop past the early embryonic stages, resulting in nonviable offspring

Question 22

What is an example of hybrid sterility?

Answer 22

An example of hybrid sterility is when hybrids are sterile due to abnormal development of gonads or abnormal segregation of chromosomes during meiosis.

Question 23

What is an example of hybrid breakdown?

Answer 23

An example of hybrid breakdown is when F1 hybrids are normal, vigorous, and viable, but the F2 generation contains many weak or sterile individuals, leading to decreased viability and fertility in subsequent generations.

Question 24

What is allopatric speciation, and what does it involve?

Answer 24

Allopatric speciation occurs when some members of a population become geographically separated from other members, preventing gene flow. It involves geographic barriers such as bodies of water and mountain ranges.

Question 25

What is sympatric speciation, and how does it occur?

Answer 25

Sympatric speciation occurs when members of a population initially occupy the same habitat within the same range but diverge into two or more different species due to abrupt genetic changes that quickly lead to reproductive isolation.

Question 26

What is parapatric speciation, and under what conditions does it occur?

Answer 26

Parapatric speciation occurs when groups that evolve into separate species are geographic neighbors. Gene flow occurs, but with reduced distances. It involves an abrupt change in the environment over a geographic border and strong disruptive selection.