Which environmental factor could lead to a decrease in genetic variation in a population of tuna? an increase in food availability
an increase in pollution
a decrease in tuna fishing
a decrease in tuna predators

The environmental factor that leads to a decrease in genetic variation in a population of tuna is :

B) An increase in pollution

The  link between genetic variation and environmental pollution, the latter being a factor that adversely affects the variation of a particular population. The concept of environmental stress not only means low reproductive rates, but  is also a factor that impedes genetic exchange with other populations and reduces the genetic diversity of the population. For this reasons, increased contamination means a decrease in the genetic diversity of the tuna population.

Thus, the correct answer is B.

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The environmental factor that could lead to a decrease in genetic variation in a tuna population is an increase in pollution (second option).

Explanation:

There is a correlation between genetic variability and environmental pollution, the latter being a factor that impacts negatively on the variability of a specific population.

The concept of pollution stress not only implies a low rate of reproduction, but it is also a factor that prevents genetic exchange with other populations, which is a factor that makes the genetic variability decrease in a population.

For these reasons an increase in pollution implies a decrease in genetic variability in a tuna population.

Other options, such as an increase in food availability, a decrease in tuna fishing or a decrease in tuna predators, are environmental factors that contribute to increased genetic variability.

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