In which condition the gene ratio remains constant for any species ?

Options

A. sexual selection
B. rendom mating
C. mutation
D. gene flow

Answer

To determine the conditions under which the gene ratio remains constant for any species, we refer to the Hardy-Weinberg principle. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding the Hardy-Weinberg Principle**:
The Hardy-Weinberg principle states that in a large population, the allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary influences.

2. **Identifying the Conditions for Constant Gene Ratios**:
For the gene ratio (allelic frequency) to remain constant, certain conditions must be met. These conditions include:
- **Large Population Size**: The population must be large enough to prevent random changes in allele frequencies (genetic drift).
- **No Mutations**: There should be no new mutations that alter allele frequencies.
- **No Gene Flow**: There should be no migration of individuals into or out of the population, which could introduce new alleles or remove existing ones.
- **Random Mating**: Mating must be random, meaning individuals pair by chance rather than by phenotype or genotype.
- **No Natural Selection**: All individuals must have equal chances of survival and reproduction, meaning no selective pressures favoring certain alleles over others.

3. **Conclusion**:
If all these conditions are met, the gene ratio will remain constant across generations for any species.

### Final Answer:
The gene ratio remains constant for any species under the conditions of the Hardy-Weinberg equilibrium, which includes a large population size, no mutations, no gene flow, random mating, and no natural selection.

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