Table 2. Comparisons of Genetic Approaches
| Genetic Strategy |
Diallele Crosses |
Selection |
QTL Maps |
RI |
F2 |
Random Mutants |
Targeted Mutants |
| Source of variation |
Existing |
Existing |
Existing |
+ |
+ |
New random induced |
New targeted |
| No. genes |
Multigenic |
Multigenic |
Multigenic |
+ |
+ |
Single gene |
Single |
| Type of output |
Heritability (h2) |
(h2) |
(h2), Map |
+ |
+ |
Map location gene ID |
Phenotypic data |
| ID of novel genes? |
No |
No |
Yes |
|
|
Yes |
Not relevant |
| Advantages |
Quick |
Provides animal line |
Single genes |
+ |
+ |
Single genes |
Known genes |
|
Genotypes replicable |
|
Stable genotype |
+ |
- |
Speedy cloning |
Much background information |
| Problems |
No individual gene ID |
Lengthy |
Complex QTL to gene |
|
|
Many genes missed |
No novel genes |
| Question addressed |
Is there genetic variance (VG)? |
Is there VG? |
How much VG? |
|
|
Can genes be found? |
Function: known genes |
|
How much VG? |
Limits of VG selection? |
Where are genes? |
|
|
What are the genes? |
|
| Costs per experiment |
$ |
$$ |
$$$ |
|
|
$$$ |
$ |
|
Note: QTL Maps = quantitative trait loci maps.
