Chromosome number variation of the Italian endemic vascular flora. State-of-the-art, gaps in knowledge and evidence for an exponential relationship among even ploidy levels

By

Bedini, Gianni
Garbari, Fabio
Peruzzi, Lorenzo

Type

Article

Date of Publication

2012

Original Publication

Comparative cytogenetics : international journal of plant & animal cytogenetics, karyosystematics and molecular systematics

Volume

6

Series / Issue

Issue: 2

Pages

191-211

Subjects

B-chromosomes , cytotaxonomy , endemics , Evolution , Italy , polyploidy

Contributed by

Pensoft Publishers

Language

English

Published by

St. Petersburg, Russia [Published] with technical support of Zoological Institute RAS [2007]-

Identifiers

DOI: https://doi.org/10.3897/compcytogen.v6i2.3107

 

Abstract

The Italian endemic vascular flora is composed of 1,286 specific and subspecific taxa. From the critical analysis of 'Chrobase.it', 711 of them (about 55%) have been studied from a karyological point of view. These taxa belong to 52 out of 56 families and 204 out of 284 genera. These data suggest that endemic species are more studied than the flora as a whole. Mean chromosome number for Italian endemics is 2n = 30.68 ± 20.27 (median: 2n = 26, mode: 2n = 18). These values are very close to those known for the whole flora. Similar variation ranges, among endemics and species with wider distribution, are likely to reflect similar evolutionary trends. Known chromosome numbers in Italian endemics range from 2n = 8 to 2n = 182. About 9% of taxa show more than one cytotype and the frequency of Bs in the Italian endemic vascular flora is 3.3%. These values are slightly smaller compared with the whole Italian flora. Finally, for the basic chromosome numbers x = 7, 8, 9, the proportion of diploids (2n = 2x) to even polyploids (2n = 4x, 6x, 8x and 10x) can be described by the exponential function f(p) = e(5.539 – 0.637p) (R2 = 0.984).