Question

Determine if each example of reproductive isolation is prezygotic or postzygotic.

1 - Two bird species have very different song patterns for mate recognition.
2 - Pink and black abalone spawn at the same time, but their sperm do not cross-fertilize each other's eggs.
3 - One species of flower is night-blooming, and another blooms during the day.
4 - Two morphologically similar lizards have sterile progeny.
A) 1. Prezygotic; 2. Postzygotic; 3. Prezygotic; 4. Postzygotic
B) 1. Postzygotic; 2. Prezygotic; 3. Prezygotic; 4. Postzygotic
C) 1. Prezygotic; 2. Prezygotic; 3. Postzygotic; 4. Postzygotic
D) 1. Postzygotic; 2. Postzygotic; 3. Prezygotic; 4. Prezygotic

Answer 1

The scenarios described involve both prezygotic barriers, which prevent fertilization, and postzygotic barriers, which result in inviable or sterile offspring. The correct classification is A): 1. Prezygotic; 2. Prezygotic; 3. Prezygotic; 4. Postzygotic.

Step-by-step explanation:

Reproductive isolation mechanisms are classified into two groups: prezygotic barriers and postzygotic barriers. Prezygotic barriers prevent the fertilization of eggs, hence no zygote is formed. Postzygotic barriers occur after fertilization and involve issues that typically lead to the inviability or sterility of the offspring.

Two bird species have different song patterns for mate recognition, which is a form of behavioral isolation, a prezygotic barrier.

• Pink and black abalone spawn at the same time, but sperm do not cross-fertilize: a gametic isolation, another prezygotic barrier.
• One species of flower is night-blooming, and another blooms during the day, an example of temporal isolation, a prezygotic barrier.
• Two morphologically similar lizards have sterile progeny, this is a clear case of a postzygotic barrier.

The accurate answer is A) 1. Prezygotic; 2. Prezygotic; 3. Prezygotic; 4. Postzygotic.