Polyploidy is a primary mechanism of rapid sympatric speciation in flowering plants. Arrange the following steps of allopolyploid speciation in the correct chronological sequence from initial interbreeding to the formation of a fertile new species.
- 1Two distinct diploid plant species interbreed to produce a diploid interspecific hybrid.
- 2The resulting hybrid exhibits complete sterility due to the failure of non-homologous chromosomes to pair during meiosis.
- 3Spontaneous chromosome doubling occurs through non-disjunction, duplicating every chromosome within the hybrid lineage.
- 4Normal meiotic chromosome pairing is restored, producing a fertile polyploid species reproductively isolated from both parent species.
Answer
The correct sequence of allopolyploid speciation begins with interspecific hybridization between two parental species, followed by hybrid sterility due to unpaired non-homologous chromosomes, subsequent spontaneous chromosome doubling (polyploidization), and finally the restoration of fertility establishing a novel, reproductively isolated polyploid species.
Allopolyploidy represents a mode of sympatric speciation driven by hybridization followed by genome duplication. The process initiates when two related but distinct species interbreed to produce an interspecific hybrid. This hybrid is initially sterile because its chromosomes are non-homologous and cannot pair during meiosis. When spontaneous chromosome doubling occurs, every chromosome acquires an identical partner, which restores balanced meiotic division and fertility. The resulting polyploid population is fertile among itself but reproductively isolated from both parent species, constituting a new species.
Step-by-Step Solution
Key Concept
Allopolyploid Speciation
Estimated Time:1m 30s