Dobzhansky's classifications of reproductive isolating mechanisms include: (A) Habitat selection (B) Flowering time (C) Sexual isolation (D) Isolation by pollinators (E) Hybrid vigour
Choose the most appropriate answer from the options given below:

Correct option is D

The correct answer is (d) A, B, C, D only. Let’s review each option:
1. (A) Habitat selection: Correct. This is a type of prezygotic isolation where different species prefer different habitats, preventing interbreeding.
2. (B) Flowering time: Correct. Known as temporal isolation, this occurs when species reproduce at different times or seasons, preventing interbreeding.
3. (C) Sexual isolation: Correct. Also called behavioral isolation, this occurs when species have different mating behaviors or preferences.
4. (D) Isolation by pollinators: Correct. This is a form of mechanical or ecological isolation where different species rely on specific pollinators, preventing cross-pollination.
5. (E) Hybrid vigour: Incorrect. Hybrid vigour (heterosis) refers to the enhanced growth or fertility of hybrid offspring and does not function as a reproductive isolating mechanism. In fact, it involves successful reproduction, whereas isolating mechanisms prevent reproduction.
Information Booster 1. Types of Reproductive Isolation:
· Prezygotic Isolation: Prevents fertilization from occurring (e.g., habitat, temporal, and mechanical isolation).
· Postzygotic Isolation: Occurs after fertilization, leading to infertile or inviable offspring.
2. Examples of Prezygotic Isolation:
· Habitat Isolation: Species live in different habitats (e.g., aquatic vs. terrestrial).
· Temporal Isolation: Different breeding times (e.g., spring vs. summer).
· Behavioral Isolation: Different mating rituals or signals.
· Mechanical Isolation: Differences in reproductive structures.
3. Dobzhansky's Contribution:
· Theodosius Dobzhansky played a crucial role in developing the modern synthesis of evolution and identifying various isolating mechanisms.
Additional Knowledge · Hybrid Vigour (Heterosis):
· Refers to the improved or enhanced traits of hybrid offspring compared to their parents.
· It is not a mechanism of reproductive isolation; rather, it shows the success of interbreeding.