Microgeographic genome size differentiation of the carob tree, Ceratonia siliqua, at 'Evolution Canyon', Israel.
OBJECTIVE
We tested whether the local differences in genome size recorded earlier in the wild barley, Hordeum spontaneum, at 'Evolution Canyon', Mount Carmel, Israel, can also be found in other organisms. As a model species for our test we chose the evergreen carob tree, Ceratonia siliqua.


METHODS
Genome size was measured by means of DAPI flow cytometry.


RESULTS
In adults, significantly more DNA was recorded in trees growing on the more illuminated, warmer, drier, microclimatically more fluctuating 'African' south-facing slope than in trees on the opposite, less illuminated, cooler and more humid, 'European' north-facing slope in spite of an interslope distance of only 100 m at the canyon bottom and 400 m at the top. The amount of DNA was significantly negatively correlated with leaf length and tree circumference. In seedlings, interslope differences in the amount of genome DNA were not found. In addition, the first cases of triploidy and tetraploidy were found in C. siliqua.


CONCLUSIONS
The data on C. siliqua at 'Evolution Canyon' showed that local variability in the C-value exists in this species and that ecological stress might be a strong evolutionary driving force in shaping the amount of DNA.
Bures
Petr
P
Department of Botany, Masaryk University, Kotlárská 2, 611 37 Brno, Czech Republic.
Pavlícek
Tomás
T
Horová
Lucie
L
Nevo
Eviatar
E
D005075:Biological Evolution; D018744:DNA, Plant / Q000032:analysis; D004171:Diploidy; D007887:Fabaceae / Q000235:genetics*; D018745:Genome, Plant; D007557:Israel; D008834:Microclimate; D008957:Models, Genetic; D012044:Regression Analysis
D018744:DNA, Plant