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(Aaronsohn and Schweinfurth 1906; Aaronsohn
1910, 1913; Schiemann 1956; Feldman 1977;
Nevo 1983, 1989, 1994, 2001). The genetic
resource value of
T. dicoccoides
for wheat improve-
ment far exceeded Aaronsohn's vision (Nevo
2001; Peng et al., 2000a,b,c). In the northeastern
distribution area of
T. dicoccoides,
where the sym-
patric area of
T. araraticum
is located, the two
species are separated by strong sterility barriers
(Maan 1973). Even though they are similar mor-
phologically, they are practically indistinguish-
able without cytogenetic analysis.
Triticum dicoccoides
, like
T. boeoticum
, was col-
lected for human consumption long before its
domestication (Kislev et al., 1992; Zohary and
Hopf 1993; Lev-Yadun et al., 2000; Nesbitt 2001).
Brittle
T. dicoccoides
-like plants with relatively
narrow grains appeared in early Neolithic and
Natufi an Near Eastern settlements. However, 9-
10 millennia ago, they also coexisted with non-
brittle seeds in Turkey (Jarmo, Iraq, Cayonu)
(Hillman and Colledge 1998), in northern Syria
(Tel Aswad and Tel Abu Hureira) (Zohary and
Hopf 1993; Nesbitt 1998; Nesbitt and Samuel
1998; Lev-Yadun et al., 2000), and in Syria (Tell
Mureybet I and II; 9000-8000 BC).
Triticum
dicoccoides
was also discovered in Neolithic sites
in Syria (Jerf el-Ahmar, Mureybet III, and Djade)
and Turkey (Cayonu) (8000-7500 BC) and in
sites near pre-Neolithic Turkey (Hallan Cemi
Tepesi) and Iraq (Neolithic Qermez Dere and
M'lefaat) (Nesbitt 1998; Lev-Yadun et al., 2000).
Domesticated forms appeared in core-area Neo-
lithic sites in Syria (Tell Abu Hureira 2A) and
Turkey (Cafer Huyuk) about 7500 BC, and soon
thereafter in Turkey (Cayonu and Nevali Cori)
(Kislev et al., 1992; Nesbitt and Samuel 1998).
From the early beginnings of agriculture in the
Near East, 10,000 years ago and throughout
the Chalcolithic and Bronze times, emmer was
the principal wheat of newly established farming
settlements; approximately 7000 years ago it
spread from there to Egypt, the Indian Subcon-
tinent, and Europe.
Patterns of allozyme diversity in wild
T. dicoc-
coides
suggest the following: (i) during the evolu-
tionary history of wild
T. dicoccoides
, diversifying
and balancing natural selections, through climatic,
edaphic, and biotic factors, were major agents of
creating genetic structure and maintaining dif-
ferentiation; (ii) wild
T. dicoccoides
harbors large
amounts of genetic diversity that can be utilized
to improve both tetraploid and hexaploid wheat.
Wild
T. dicoccoides
grows extensively in the
catchment areas of the Upper Jordan Valley (in
northern Israel, in the eastern Upper Galilee
Mountains, and the Golan Heights). Elsewhere in
the Fertile Crescent (Fig. 1.1), populations of
wild
T. dicoccoides
are semi-isolated and isolated
and display a patchy structure. The highly sub-
divided, archipelago-type ecological population
structure of wild
T. dicoccoides
is matched by its
genetic population structure. Substantially more
gene differentiation has been found within and
between populations that were sometimes geo-
graphically very close within Israel, than between
wild
T. dicoccoides
populations in Israel and
Turkey (Nevo and Beiles 1989), where 40% of
the
T. dicoccoides
genetic diversity existed within
populations and 60% existed between popula-
tions. Only 5% of the genetic diversity was found
between the Israel and Turkey metapopulations.
This conclusion was reinforced based on edaphic,
topographic, and temporal differentiation, on
local microclimatic differentiation, on the extreme
case of local isozyme differentiation in the Golan
Heights (Nevo et al., 1982; Golenberg and Nevo
1987; Nevo et al., 1988a,b), and on recent DNA
analyses (Fahima et al., 1999; Li et al., 1999,
2000a,b,c,d). The DNA results suggested that at
least part of the noncoding regions were also sub-
jected to natural selection. Genetic diversity was
eroding across coding and noncoding regions of
the
T. dicoccoides
genomes during and following
domestication (Fahima et al., 2001). The
T. dicoc-
coides
genomes have been molded, in part, by
diversifying natural selection from various eco-
logical stresses.
The genetic differentiation within and between
populations of
T. dicoccoides
was also refl ected by
an analysis of allele distribution (Nevo and Beiles
1989), which showed that 70% of all variant
alleles were not widespread but revealed a defi nite
localized somewhat sporadic distribution. Like-
wise, the analysis of genetic distances between
populations supported the conclusion that sharp
