The introduction of a small population onto an island that results in a limited gene pool for a population..?

Question

the introduction of a small population onto an island that results in a limited gene pool for a population best describes?

The sharp reduction of the gene pool and the numbers of a population through a secere epidemic is an example of?

Name source(s) of new alleles within a population?

Answer 1

> the introduction of a small population onto an island that results in a limited gene pool for a population best describes?

A "Founder effect" isolated population

> The sharp reduction of the gene pool and the numbers of a population through a secere epidemic is an example of?

Genetic drift

> Name source(s) of new alleles within a population?

Mutation

Gene flow (formerly known as migration) -- individuals from another population immigrate, bringing their alleles with them.

Lateral gene transfer - your population picks up genes from organisms of other species, or from the environment.  One mechanism for this is viral lysogeny.

Answer 2

The previous answer is excellent, except I think the term you might be looking for in the second part ("sharp reduction of the gene pool") is "bottleneck".  Bottlenecking events do result in genetic drift though, so that's still correct, but this is a more specific way of describing the event you're talking about.