The Barton Springs salamander is an endangered species found only in a single spring in the city of Austin, Texas. There is growing concern that a chemical spill on a nearby freeway could pollute the spring and wipe out the species. To provide a source of salamanders to repopulate the spring in the event of such a catastrophe, a proposal has been made to establish a captive breeding population of the salamander in a local zoo. Suppose you are asked to provide a plan for establishing this captive breeding population, with the goal of maintaining as much of the genetic variation of the species as possible in the captive population. What factors are likely to lead to a loss of genetic variation in the captive population?

Nonrandom mating is when an organism chooses a mate based on certain traits that the mate has. This decreases genetic variation, especially if the salamanders choose mates that have very similar traits to itself leading to the possibility of inbreeding. Inbreeding can lead to sterility and low survival rates which also decreases the genetic variation of the captive population of salamanders.

Genetic drift caused by a population bottleneck (where a small group of individuals are separated from the main population) can cause a change in allele frequency of the captive population. This could be an increase or decrease in allele frequency. An increase in an allele's frequency will occur until it is the only allele in the captive population, while a decrease in an allele's frequency will occur until it is no longer in the population at all. Both these occurrences could decrease the genetic variation in the captive salamander population.