Olive Domestication

Olea europaea •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 yearsKohler's Medizinal-Pflanzen in naturgetreuen

Abbildungen mit kurz erlauterndem Texte : Atlas zur Pharmacopoea germanica,  Volume 2 (1887)

Oleaceae phylogeny

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.

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Olea europea ssp. europaea2 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)

• 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.

• Kfar Samir - coast off of Haifa: olive oil extraction site (7530-6570 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

Olive Pit Collection Sites

Elbaum et al. only had 2 pits with high quality DNA

• Amplified 109 bp segment from TrnT-TrnL 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

PhylogeographyCatherine 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.

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:

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

EAST

The above oleasters and over 100 cultivars

<1/4

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

Oleasters

CultivarsTotalSpecific to East

Specific to West

Mitotypes 3 1 2 4

RAPD 57 6 12 45

SSR 167 12 33 99

Cultivars are generally of

eastern origin.

“Some cultivars possess western-specific 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

• CV=cultivated; W=wild; AT=ancient

• UM=Umbria, SA=Sardinia, SI=Sicily

Pairwise estimated Variance for cultivated, wild and ancient olives

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Baldoni et al. 2006

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

Breton et. al. 2006

Three refugia:

1. NW Africa

2. W. Med.

3. Near East

Genetic diversity and gene flow between the wild olive and the olive: several Plio-Pleistocene

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 RPOPs1. Corsica; 2. Turkey; 3. Sicily;4. Tunisia; 5. Libya; 6. Spain; 7. Israel

Map of RPOPs

• 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.

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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?

BibliographyBaldoni. 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 Plio-Pleistocene 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.

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