Adil GÜNER, Vehbi ESER - optima

Oral Lectures
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CHENOPODIACEAE IN THE MEDITERRANEN AND THEIR
EVOLUTIONARY RELATIONSHIPS TO THE IRANO-TURANIAN
REGION
Helmut FREITAG 1 , Gudrun KADEREIT 2
1 University of Kassel, Faculty of Science (FB 18), Institute of Biology, Kassel, Germany hfreitag@unikassel.de
2 University of Mainz, Faculty of Biology (FB 10), Institute of Systematic Botany, Mainz, Germany
clausing@mail.uni-mainz.de
The Mediterranean and the Irano-Turanian regions are comparatively rich in Chenopo-diaceae,
with c. 280 and 350 spp., respectively. Most of them are ecologically specialized as (1)
halophytes – growing on strongly saline or alkaline soils, as, e.g., coastal lagoons and depressions
in arid areas, (2) xerophytes – in steppes, semi-deserts and deserts, and (3) ruderals – on disturbed
sites. The chenopod floras of both regions are related. They have many species in common,
preferably annuals of subf. Chenopodioideae. Others penetrate more or less into the adjoining
region, but very many are confined to the one or the other region due to ecological constraints or
to limited dispersal abilities. Recent phylogenetic studies carried out in different subfamilies of
Chenopodiaceae have shown that the major lineages were present and started to diversify
obviously already in the Early Tertiary in an area around or at the northern shores of the former
Tethys that reached to C Asia and the Indian Ocean. Their further diversification and
regionalization was strongly favored by increasing aridity and continentality in the eastern
section associated with the disintegration of the Tethys. Later periods of climatic deterioration, in
particular the Messinian salinity crisis of the Upper Miocene and the cool and dry periods of the
Pleistocene caused invasions of certain taxa from today’s Irano-Turanian region into the
Mediterranean, where subsequently, after having been isolated, they underwent separate
speciation processes. Plant geographical and molecular evidence of these intricate relations will
be presented from different groups, mainly from subf. Salicornioideae and Camphorosmoideae.
As fossils are extremely rare, the time of the respective splits can be tentatively estimated by
molecular clock analyses only.
Keywords: Chenopodiaceae, diversification, molecular clock, Tethys
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