Evolution change in small populations,,, I don't understand!!!!!!?

Question

Natural selection guides evolutionary change in large populations. What possible events
(beside natural selection) could lead to evolutionary change in small populations? What
is the collective term used for these changes in the gene pool?

Answer 1

Besides natural selection, I suppose geographic isolation could lead to evolutionary change. For example, if one population gets separated by something like a body of water or mountain, then varying environments (as well as now different gene pools) could change the populations enough so that they become distinct from each other.

Answer 2

natural selection is more apparent in small populations.
bascically natural selection leads to a change in allele frequency eg from 1 form to another due to selection pressures form the environment.

If you have a small population these changes are magnified more greatly as the gene pool is smaller and there is greater inbreeding.

you can get small populations and changes in allele frequencies in the "Founder Effect" where a small number of individuals move to an isolated place and there is little or no gene flow with other populations. If certain members of that population have a specific trait or character not often seen in large or other popuations it can become more frequent eg in the Amish (which came from Germany) their most common blood type is different to that of the general american population and there is a higher incidence of polydactly (6 fingers and toes on each hand) as one of the orignal ancestors had this condtition.

The other is the bottleneck effect where the majority of a population is wiped out in a disaster, leading to selected members surviving. THe disaster may have been a disease, of which only members resistant to it survived, their alleles would then become more popualar over time. If the disaster was a natural disaster, which is less selective for specific traits ie its kills randomly) its chance as to what alleles the surviving members have. THese may then increase over time and certain traits may be lost over time and maybe a new species will form.

Answer 3

Population size is irrelevant. Natural selection still applies. If there are a group of 10 individuals in a species, then any change which leads to an increased survival and increased offspring will be favoured.
With small groups, sometimes natural disasters can affect change, such as drought wiping out specific crops or food sources, and there not being enough diversity in a small population to survive a large drop in population.

Answer 4

The answer your teacher is looking for is:
Genetic drift.
This is especially important in small isolated populations. A small isolated population may start out with only one, two, or a few individuals; these individuals ("founders") will not have the full set of alleles from their parent population by dint of being so few.
More alleles can be lost through the happenstance death of the only individual in a population bearing them. In a large population, it's likely that any particular allele will be found in several individuals.

Answer 5

Small populations can change through the effects of mutations. Mutations are changes in the genotype of an organism which in turn changes its phenotype. These changes affect the organism's ability to live and reproduce under different constraints. These traits are passed on to offspring and is a form of evolution.

Answer 6

it might have something to do with where they live and wut they eat and wut chemicals they are exposed to and all that stuff