Final answer:
The frequency of allele L on Martha's Vineyard after two generations cannot be precisely determined with the information given, but due to genetic drift, it is expected to be slightly higher than 0.6, though no exact value can be calculated.
Step-by-step explanation:
To determine the frequency of the dominant allele L after two generations on Martha's Vineyard, we need to understand the concept of genetic drift, which is a mechanism of evolution that describes how allele frequencies can change arbitrarily over time, especially in small populations. Since 1 in 50 snails migrate to the island and do not return, there is a small addition of the mainland allele frequency to the island population. Given that the starting frequency of allele L on the island is 0.6 and that the infusion of new alleles is minimal with a frequency of 0.05 from the mainland, allele L's frequency on the island will be governed by genetic drift more than by the new migrants.
The Hardy-Weinberg principle can typically be used in larger populations to predict allele frequencies; however, in small populations or in cases of migration, we need to account for genetic drift and gene flow. Assuming no other evolutionary forces are at play, such as selection, mutation, or non-random mating, we can estimate the frequency of allele L over two generations with some simple calculus. Unfortunately, without any given formula or additional information on reproduction rates and the number of migrants per generation, we cannot accurately quantify the change in frequency.
However, because genetic drift has a stronger impact on smaller populations and the contribution of migrants is low, we can expect allele L to increase in frequency over two generations given its already high initial frequency on the island. The final answer is likely to be closer to the initial 0.6 frequency, with a slight increase due to the introduction of new alleles. The exact value is not determinable with the information provided.