What is polyploidy and how can it lead to instant speciation in plants?

What is polyploidy and how can it lead to instant speciation in plants?

• A. Chromosome loss reduces genetic potential and prevents speciation
• B. Crossing two species to create fertile hybrids
• C. Polyploidy is the duplication of whole chromosome sets; autopolyploidy or allopolyploidy can prevent normal meiosis, creating reproductive isolation and new species
• D. A small mutation in a single gene causing new traits

Answer: (C)

Polyploidy means having more than two complete sets of chromosomes. In plants this can happen when an extra chromosome set is created within a single species (autopolyploidy) or when two species hybridize and their chromosome sets are doubled (allopolyploidy). The key is that the organism ends up with multiple whole sets of chromosomes, which often disrupts normal pairing during meiosis with the parent population. This disruption leads to reproductive isolation: the polyploid can be fertile with other polyploids that have the same extra sets, but not with individuals from the original parent, effectively forming a new species right away. This is the mechanism behind instant speciation in many plants. So, the best description is that polyploidy is the duplication of whole chromosome sets; autopolyploidy or allopolyploidy can prevent normal meiosis, creating reproductive isolation and new species. Other options don’t capture this mechanism—chromosome loss isn’t polyploidy, a single-gene mutation isn’t about chromosome sets, and simply crossing two species doesn’t guarantee the immediate fertility reset that doubling chromosomes provides.

Polyploidy means having more than two complete sets of chromosomes. In plants this can happen when an extra chromosome set is created within a single species (autopolyploidy) or when two species hybridize and their chromosome sets are doubled (allopolyploidy). The key is that the organism ends up with multiple whole sets of chromosomes, which often disrupts normal pairing during meiosis with the parent population. This disruption leads to reproductive isolation: the polyploid can be fertile with other polyploids that have the same extra sets, but not with individuals from the original parent, effectively forming a new species right away. This is the mechanism behind instant speciation in many plants.

So, the best description is that polyploidy is the duplication of whole chromosome sets; autopolyploidy or allopolyploidy can prevent normal meiosis, creating reproductive isolation and new species. Other options don’t capture this mechanism—chromosome loss isn’t polyploidy, a single-gene mutation isn’t about chromosome sets, and simply crossing two species doesn’t guarantee the immediate fertility reset that doubling chromosomes provides.