Answer :
Answer:
The correct answer is: The limited variability in the size of shells in the initiating population.
Explanation:
- The shell size in snail species is determined by a number of variants (alleles) of the gene that is responsible for determining the size of their shell.
- The number of variants of the gene encoding for shell size is limited.
- However, the different variants may encode for different shell size, say from 5 millimetre to 20 millimetre.
- All these variants are present in the original population of snail but in different proportions.
- However, if predation tend to target the snail species with smaller shell size (5 millimetre to 10 millimetre) then evolution would tend to increase the frequency of snails having the larger shell variants (15 millimetre to 20 millimetre).
- This will result in a population of snails with increased shell size.
- However, an increase in shell size over 20 millimetre is not possible because no allelic variants encoding for a shell size greater than 20 millimetre is available in the population.
The thing that will likely limit the size of the shells is the limited variability in the size of shells in the initiating population.
It should be noted that the shell size in snail species is determined by a number of variants of the gene and this plays a vital role in the determination of the size of their shell.
The number of variants of the gene encoding for shell size is limited. In a situation whereby there's a predator that targets the snail species with smaller shell size, then evolution would increase the frequency of snails that possess larger shell variants.
Therefore, for snail species that evolve larger shells in response to predation, the limited variability in the size of shells in the initiating population will be a limiting factor.
Read related link on:
https://brainly.com/question/14244822