To determine under what conditions new species may be formed, we can analyze the given options step by step:
1. **Option (i): DNA undergoes significant changes in germ cells.**
- Germ cells, or sex cells (sperms and eggs), are responsible for passing genetic information to the next generation. If there are significant changes in the DNA of these cells, it can lead to variations in the offspring. Such variations may accumulate over generations, potentially leading to the formation of a new species. Therefore, this option is correct.
2. **Option (ii): Chromosome number changes in the gamete.**
- Changes in the chromosome number can lead to different phenotypes, as the phenotype is influenced by the genotype, which is determined by the genes present on chromosomes. If the chromosome number in gametes changes, it can result in new combinations of traits in the offspring. This can also contribute to the formation of new species. Thus, this option is also correct.
3. **Option (iii): There is no change in the genetic material.**
- If there is no change in the genetic material, the offspring will be genetically identical to their parents, much like clones. This means that no new species can be formed, as there is no variation. Therefore, this option is incorrect.
4. **Option (iv): Mating does not take place.**
- In sexual reproduction, mating is essential for the combination of genetic material from two parents, leading to genetic diversity. If mating does not occur, the organisms may reproduce asexually, resulting in clones that are genetically identical to the parent. This would not lead to the formation of new species. Hence, this option is also incorrect.
**Conclusion:**
The correct options that can lead to the formation of new species are:
- (i) DNA undergoes significant changes in germ cells.
- (ii) Chromosome number changes in the gamete.
