4.5 On the brink

Question 1

Captive breeding programme aim

Answer 1

• increase the number of individuals of the species if numbers are very low
• maintain genetic diversity within the captive population
• reintroducing animals into the wild if possible

Question 2

Genetic drift

Answer 2

The chance increase or decrease in
allele frequency over time. These differences
result from random mutation adding new alleles
to the population. They can also result from
organisms carrying particular alleles failing to
breed.

Question 3

Genetic uniformity

Answer 3

where individuals within a population have similar genotypes

Question 4

Inbreeding, Inbred, Inbreeding

Answer 4

Breeding
closely related individuals together. When this
process is carried out over several generations,
the offspring are likely to become homozygous
for increasing numbers of alleles. This helps to
give rise to new varieties. However, some of
these alleles are likely to be harmful recessive
alleles. This may result in the offspring of animals or plants which have been inbred for a
number of generations producing a lower yield
or being less fertile. It also increases the
frequency of inherited diseases and other
unfavourable characteristics.

Question 5

Inbreeding depression

Answer 5

Inbreeding is breeding
closely related individuals together. The
offspring are likely to become homozygous for
more and more harmful recessive alleles. This
may result in the offspring of animals or plants
which have been inbred for a number of
generations showing inbreeding depression and
producing a lower yield or being less fertile.
Inbreeding depression is a problem that
frequently affects small populations, whether in
the wild or in captivity. Crossing two inbred
lines produces more vigorous offspring.

Question 6

Cytogenetics

Answer 6

Looking at the structure of chromosomes