Hybrid swarms between T. dicoccoides and T. durum, as well
as highly introgressed dicoccoides populations have been encountered
in several localities in the semi-steppe hilly area of the Eastern Galilee.
From our observations they are restricted to edges of cultivation and otherwise
much disturbed ground on sites where cultivated hard wheat is grown in close
proximity to pure populations of wild emmer. A well developed hybrid swarm
(comprising several thousands of plants) was examined in detail in spring
1961 near Amiad (on the Tiberias-Safad road). It occupied the edge of a
newly constructed stone terrace and the stone heaps on the margin of a field
that had been cleared for cultivation several years previous. On the adjacent
undisturbed hillsides pure populations of T. dicoccoides were growing
in abundance. The swarm included many brittle dicoccoides-like plants,
a few plants with a tough rachis identified as the local T. durum
variety " Etit " (with which the field had been sown 3-4 years previously),
and a whole range of intermediates. These exhibited a wide diversity of
character recombinations ranging from lax to semi-dense ears, from narrow
shaped to broad, 3-kernelled spikelets, from densely hairly rachis internodes
to sparsely hairy ones-as well as wide variability in the amount of glume,
pale and awn scabrosity and keel development. Types most indicative of the
process of hybridization were the following recombinants: a) forms with
free-threshing grains and a brittle rachis; b) forms with free-or almost
free-threshing grains but an emmer-like tough rachis; c) forms with hulled
or semi-hulled grains in addition to emmer-1ike disarticulation. Most of
the intermediates and recombinants were fully or almost fully fertile.
Such hybrid swarms, as well as the ecological conditions under which they
occur, resemble the situation found in Israel also in the case of Hordeum
spontaneum and H. sativum. They indicate that T. dicoccoides
and cultivated T. durum cannot be regarded as entirely isolated from
each other. Most probably they are genetically interconnected through occasional
hybridization. This type of introgression might account for a considerable
part of the parallel variation found among wild and cultivated forms of
tetraploid wheats in the " Fertile Crescent " of the Middle East, as well
as for the origin of many of the dicoccoides-like varieties of the
local cultivated hard wheats. Such forms are thus not necessarily " primitive
" relics, but are possibly secondary products of a fairly recent hybridization.
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