Abstracts, XIV OPTIMA Meeting, Palermo (Italy) , 9-15

XIV OPTIMA Meeting, Palermo (Italy), 9-15 September 2013
A comparison of plant chromosome number variation among Corsica, Sardinia
and Sicily, the three largest Mediterranean Islands
BEDINI G., PERUZZI L.
Dipartimento di Biologia, Università di Pisa, Italy. E-mail: gbedini@biologia.unipi.it
Recent studies highlighted a trend in the increase of mean chromosome number (CN) together with
latitude. For instance, in a previous research based on the Italian, Slovakian and Polish floras, we have
demonstrated in a quantitative way that mean CN increases along a S-N latitudinal gradient. In the current
study, we compared CN variation among vascular floras of the three largest Mediterranean Islands:
Corsica, Sardinia and Sicily to verify whether patterns of variation reflect their similar latitudinal
ranges or their different biogeographic/taxonomic contexts. We computed the data from records stored
in "Chrobase.it" (www.biologia.unipi.it/chrobase), a chromosome count database for the Italian flora.
Since the three islands follow a clear latitudinal gradient, we expected a parallel difference in CN variation.
The three datasets comprised 261 (Corsica), 520 (Sardinia) and 975 (Sicily) distinct cytotypes.
Although the samples were not homogeneous in terms of number of cytotypes and representativeness
of island floras (respectively of 8%, 17%, and 28%), our results do show that mean chromosome number
increases along a S-N latitudinal gradient. Indeed, mean CN resulted to increase from Sicily, 2n =
27.48 to Sardinia, 2n = 31.88 and Corsica 2n = 33.59. The most karyologically variable species resulted
Teline monspessulana (L.) K.Koch (2n = 46, 48 + 0-4B in Sicily), Genista sulcitana Valsecchi (2n
= 18 + 0-2B, 27 + 0-2B in Sardinia) and Crocus minimus DC. (2n = 24, 25, 26, 27, 28, 29, 30 in
Corsica). Chromosome numbers range from 2n = 6 (Hypochaeris in Sicily and Sardinia) to 2n = 216
(Colchicum corsicum Baker in Corsica). Our results are consistent with the hypothesis of an increase
of polyploidy at increasing distances from the Equator, when territories from the same hemisphere are
compared, at a geographical scale such as that of Central Mediterranean Sea.
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