Conservation biologists need to understand how

1
(No Transcript)
2
Conservation biologists need to understand
how genetic diversity is maintained through
natural processes if conservation programs are to
be designed for its maintenance in managed
populations. Maintenance of extensive genetic
diversity in natural populations is one of the
most important, largely unresolved, questions of
evolutionary genetics.
3
The balance of forces maintaining genetic
diversity differs between large and
small populations. Selection has a major impact
in large populations. However, its impacts are
greatly reduced in small populations where
genetic drift has an increasingly important role.
4
Five major points about genetic diversity
in small populations Genetic drift fixes
alleles more rapidly in smaller
populations. Loci subjected to weak selection in
larger populations approach effectively neutral
in small populations. Mutation-selection
equilibria are lower in smaller than larger
populations.
5
The effects of balanced polymorphisms
depends upon the equilibrium frequency the
frequency of fixation of intermediate frequency
alleles is retarded, but balancing selection
accelerates fixation of low frequency
alleles. Balancing selection can retard loss of
genetic diversity, but it does not prevent it in
small populations. The consequence of these
effects is that genetic diversity in small
populations is lower for both neutral alleles and
those subjected to balancing selection