Agriculture Reference
In-Depth Information
(Hamisy, 2004). Knowledge of phenotypic and genetic variation is a
prerequisite for the domestication and improvement of indigenous fruits from
the wild. Within-stand genetic variation of
U. kirkiana
and
Sclerocarya birrea
trees was determined (Fig. 8.1), and implications for developing germplasm
collection and conservation guidelines were suggested (Agufa, 2002).
S. birrea
had more diversity than
U. kirkiana
in the study. The role of geography and
structure in subspecies status in
S. birrea
in contributing to the pattern of
variation was affirmed.
S. birrea
from Tanzania contained more chloroplast
variation, supporting the hypothesis that this country is the centre of diversity
and origin of
S. birrea
(Agufa, 2002).
In genetic terms, human-induced domestication results in either gain or loss
of genes, altered gene frequencies or modifications of the way genes are packed,
i.e. gene complexes (Simons, 1996). The domestication of wild fruit trees must
be seen as a continuum between the undisturbed wild state, through cultivation
of semi-domesticates, to monocultural plantation or orchards of advanced
B Chyulu (Kenya) (Sbc)
J Kalimbeza (Namibia) (Sbc)
M Pandamatenga (Botswana) (Sbc)
Chloroplast
haplotypes
R
S
U
T
K Choma (Zambia) (Sbc)
I Oshikondilongo (Namibia) (Sbc)
L Siavonga (Zambia) (Sbc)
G Mangochi (Malawi) (Sbc)
H Ntcheu (Malawi) (Sbc)
P Kalanga (Swaziland) (Sbc)
R Manyonyaneni (Swaziland) (Sbc)
N Tutume (Botswana) (Sbc)
E Magamba (Tanzania) (Sbc)
F Makadaga (Tanzania) ( Sbm)
D Mialo (Tanzania) (Sbb)
C Mandimu (Tanzania) (Sbb)
A Missira (Mali) (Sbb)
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Genetic distance
Fig. 8.1.
Phenogram-based genetic distance from 80 RAPD markers for 16 populations of
Sclerocarya birrea
sampled from eight countries in sub-Saharan Africa. Codes in
parentheses indicate subspecies designations made during collection. Sbc, ssp.
caffra
; Sbb,
ssp.
birrea
; Sbm, ssp.
multifoliolata
(Agufa, 2002).
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