000 02166nam a2200205 a 4500
003 AR-ReUNN
005 20260702154413.0
008 260630s1967 dk |||||||||||||||||eng
041 0 _aeng
100 1 _aSnogerup, Sven
_9160660
245 1 0 _aStudies in the aegean flora IX. Erysimum sect. cheiranthus B. variation and evolution in the small-population system / Sven Snogerup
264 1 _aCopenhagen
_bCouncil for Nordic Publications in Botany
_c1967
300 _c24 x 16 cm
520 _aThe following taxa are accepted: E. Candicum Snog. ssp. candicum, E. candicum ssp. carpathum Snog., E. rhdium Snog., E. naxense Snog., E. senoneri (Heldr. & Sart.) Wettst. ssp. senoneri, E. senoneri ssp. amorginum Snog., E. senoneri ssp. icaricum Snog., E. corinthium (Boiss.) Wettst., E. cheiri (L.) Cr. The wild taxa occur in the Aegean islands and southern Greece and are, with one exception, obligate chasmophytes. The total number of populations known hitherto is only 107. As the populations consist of only 1-2000 individuals and are isolated, the variation and evolution in each population occurs mainly by genetic drift. The results are then subject to interpopulation selections. The small-population system is considered to have existed as such sincePliocene. The evolution leading to the formation of the present taxa from a common ancestral stock is considered to have occurred since the breakdown of the Aegean mainland, i.e. since middle or late Pliocene. High mutability and high frequency of cytologic changes have been observed in the small populations. This is assumed to depend on lack of stabilizing gene systems, which are favoured by selection in large populations. The chromosome number of all taxa is 2n=12. Artificially produced hybrids indicate sterility barriers of various strength beween the taxa. E. senoneri ssp. amorginum has developed a phrygana ecotype and is apparently leaving the cliffs and spreading in another habitat. The cultivated E. cheiri is considered to have originated from crossings of wild taxa.
650 4 _aErysimum
_9160661
650 4 _aEvolución
_96487
942 _cLIB
035 _a(IBONE)75126
001 245919
999 _c245919
_d245919
040 _aAR-ReUNN
_bspa
_cAR-ReUNN
_eaacr2