Olive
Domestication
Olea europaea
Kohler's Medizinal-Pflanzen in naturgetreuen Abbildungen mit
kurz erlauterndem Texte : Atlas zur Pharmacopoea
germanica, Volume 2 (1887)
•Family: Oleaceae
•Six subspecies
•Olea europaea ssp.
europaea (olives) grows in
Mediterranean Basin at the
N limit of Olea range
•Other 5 subspecies grow in
Africa and Asia
•Olea fruit gathered 19,000
year BP in E. Mediterranean
•One of the first plants cited
in early literature
•Can live 2000-3000 years
Oleaceae phylogeny
www.ruhr-uni-bochum.de/.../ Olea.europaea.ho5.jpg
Wallander, E. and V. A. Albert. 2000. Phylogeny and classification of Oleaceae beased on rps16 and
trnL-F sequences. American Journal of Botany 12: 1827-1841.
Olea europea ssp. europaea
2 practically indistinguishable varieties:
• Olea europaea ssp. europaea var. sylvestris =
wild olive, ancestor of cultivated olive.
• Olea europaea ssp. europaea var. europea =
cultivated olive
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Olea europaea ssp. europaea
var. europaea (cultivated olive)
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•
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•
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Wind pollinated and diploid
Propagated by cuttings or grafting
Self incompatible; male often sterile
Morphologically very similar to oleaster
90% of olives grown
for oil production
• “healing leaf”
Ancient olive DNA in pits:
preservation, amplification and
sequence analysis (Elbaum et al. 2006)
• Archeological studies verify intensive
exploitation of fruit 8000 years ago.
• Developed method to select pits with
high quality DNA-Mediterranean climate
is not favorable for DNA preservation
• Successfully sequences first ancient
olive DNA.
Olive Pit Collection Sites
• Kfar Samir - coast off of Haifa:
olive oil extraction site (75306570 BP); 3 pits analyzed
• Nahal Megadim - off Carmel
coast: 6 (6115 BP), 6 pits
analyzed
• Qumran: hundreds of
desiccated olive pits, date
palm pits found in a Byzantine
layer (1430 BP); 10 pits
analyzed
Elbaum et al. only had 2 pits
with high quality DNA
• Amplified 109 bp segment from TrnTTrnL in chloroplast genome. Only 35 bp
could be read; for these, the sequence
was identical to the database for
modern O. europaea.
Today olives are cultivated throughout the
Mediterranean Basin, as well as in CA,
Argentina & Australia.
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Breton et al. 2006
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Using Multiple Types of Molecular
Markers to Understand Olive
Phylogeography
Catherine Breton, Guillaume Besnard, and André A. Bervillé
Breton et al. used mitotypes, SSR and
RAPD data to gain better understanding of
olive domestication.
Previous hypotheses on olive
domestication and distribution:
•
•
First believed that domesticated olive was
introduced to the Mediterranean Basin
More recently scientists hypothesized:
1. The wild olive was only in E. Med.
2. Cultivars were derived in the East and
spread West.
3. “Wild” olives in the West are all feral
escapes.
However, Breton et al. propose:
1. There is an obvious genetic difference
between eastern and western oleaster
populations; the western populations are
not feral.
2. These disjunct populations, which have
different mitotypes, are the result of
multiple isolated refugia during the
glaciations.
3. According to SSR and RAPD data,
oleaster genetic diversity is higher in the
western Mediterranean than in the East.
However, Breton et al. propose:
4. Generally cultivars are of eastern origin.
5. Olive cultivars on Corsica & Sicily may
have been directly selected from ancient
native oleasters (based on MCA).
6. O. europaea ssp. europaea arose and
diversified in Morocco, where it picked up
the MCK mitotype.
7. At least two simultaneous domestications
occurred on opposite ends of the Basin.
Oleaster population
collections
<1/4
E
A
S
T
The above oleasters and over 100 cultivars
Oleaster genetic diversity is higher in the
western Mediterranean than in the East
and higher in oleaster than in cultivars:
From Table 11. 3: Distribution of Molecular in
Oleasters and Olive Cultivars
Type of
Marker
Mitotypes
Total
3
RAPD
SSR
57
167
Oleasters
Specific Specific
to East to West
1
2
6
12
12
33
Cultivars
4
45
99
Cultivars are
generally of
eastern origin.
“Some cultivars
possess westernspecific oleaster
RAPD bands as well
as western-specific
mitotypes, suggesting
that these cultivars
were selected directly
from oleasters in the
western
Mediterranean.”
SSR-based
dendrogram
showed 3 main
groupings: western
Med, eastern Med
and Corsica/Sicily
Pairwise estimated Variance for
cultivated, wild and ancient olives
Baldoni et al. 2006
• CV=cultivated; W=wild;
AT=ancient
• UM=Umbria, SA=Sardinia,
SI=Sicily
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Ancestry of oleaster
• Mitotype data show 2 mitotypes (MOM and MCK)
not found in other subspecies. The authors note that
the MCK type is very similar to MMA found in O. e.
maroccana. This supports the hypothesis that
oleaster diversified in the West. Breton et al.
suggest a southern Moroccan diversification.
• Chlorotype data also show that O. e. europaea has
chlorotypes from two distinct lineages, implying that
it may be a hybrid.
Oleaster and
cultivar
movement
Three refugia:
1. NW Africa
2. W. Med.
3. Near East
Breton et. al. 2006
Genetic diversity and gene flow between the
wild olive and the olive: several PlioPleistocene refuge zones in the Mediterranean
basin suggested by SSR analysis.
Breton, C., Tersac, and A. Bervillé. Journal of Biogeography (2006) 33
166 oleaster species and 40 cultivars were used:
• Chlorotype data from 12 unlinked SSR loci
• Constructed ancestral populations (RPOP)
Found:
• Diversity of oleasters, with unique populations,
can be explained by glacial refugia.
• Used STRUCTURE to assign each
individual to one or several RPOP (80%
probability, if less then possibly hybrid)
• Seven pre-defined RPOPs
1. Corsica; 2. Turkey; 3. Sicily;
4. Tunisia; 5. Libya; 6. Spain; 7. Israel
Map of RPOPs
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•
Figure 4 Map of the Mediterranean basin showing the approximate locations of
the seven oleaster populations. RPOPs are circled by continuous lines and
numbered according to Table 4. Dotted circles indicated that the two RPOPs
were not differentiated by all methods.
Conclusions:
• Distribution of oleaster diversity can be
explained by recolonization into the
Mediterranean Basin after the last
glaciation.
• There is gene flow between some
populations due to overlap
Questions:
• If there were at least 2 sites of olive domestication,
why do most cultivars have a high percentage of
ME1 mitotype?
• Given that oleaster has more genetic diversity, why
do cultivars have an additional mitotype?
• Is it likely that the mitotype presence was biased by
large sample size in West and small in the East?
• Why not use phylogenic analysis of molecular data
instead of dendrogram?
• Only 1 to 2 samples of the other O. europaea
subspecies were examined. Is this sufficient?
Bibliography
Baldoni. et al. 2006. Genetic structure of wild and cultivated
olives in the Central Mediterranean Basin. Annals of Botany
98: 935-942
Breton, C., Tersac, and A. Bervillé. 2006. Genetic diversity and
gene flow between the wild olive and the olive: several PlioPleistocene refuge zones in the Mediterranean basin suggested
by SSR analysis. Journal of Biogeography 33: 1916-1928.
Breton, C., G. Besnard, and A. A. Bervillé. 2003. Using multiple
types of molecular markers to understand olive
phylogeography. Documenting Domestication.
Elbaum, R. et al. 2006. Ancient olive DNA in pits: preservation,
amplification and sequence analysis, Journal of Archaeological
Science 33: 77-88.
Wallander, E. and V. A. Albert. 2000. Phylogeny and
classification of Oleaceae based on rps16 and trnL-F
sequences. American Journal of Botany 12: 1827-1841.