A haploid sperm from one species and a haploid egg from another species may form a diploid interspecies hybrid. Meiosis in these plants generally…
A haploid sperm from one species and a haploid egg from another species may form a diploid interspecies hybrid. Meiosis in these plants generally fails but can also lead to rare duplicated gametes called:
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Correct Answer: Option A
Explanation
Interspecific hybridization and allopolyploidy:Creating a new fertile allopolyploid species through interspecific hybridization:Step 1: Cross two different species (Species A × Species B) → Sterile F1 hybrid (diploid, 2n)• Sterile because chromosomes from different species cannot pair properly during meiosis.Step 2: Rare spontaneous events produce UNREDUCED gametes (diploid gametes instead of haploid) due to meiotic failure.Step 3: Fusion of two such unreduced gametes → ALLOPOLYPLOID with chromosome sets from BOTH species.• Now can undergo meiosis normally (each chromosome has a homologue from the same species set).• Fertile, but reproductively ISOLATED from both parental species (different chromosome numbers).Historical example: Raphanus (radish, n=9) × Brassica (cabbage, n=9) → Raphano-brassica (2n=36, allotetraploid).This is the dominant speciation mechanism in plants (polyploidy).Answer: Interspecific hybridization → sterile diploid; unreduced gametes → fertile allopolyploid (chromosomes from both species).