Ploidy levels and their relationships with the rainfall in several populations of Patagonian species ofBerberisL

Abstract

-The ploidy levels and pollen staining of 68 populations belonging to 13 species of the genus Berberis L., growing in the Argentinian Patagonia under different environmental conditions, were analyzed as a part of a multidisciplinary study to obtain information about the evolutionary history of the genus. The chromosome number at Berberis bidentata, B. cabrerae, B. chillanensis, B. darwinii, B. empetrifolia, B. ilicifolia, B. linearifolia, B. micro-phylla, B. montana, B. parodii and B. serrato-dentata is 2n = 28, whereas B. buxifolia and B. heterophylla have 2n -56. The relationship between ploidy levels and rainfall showed that, contrarily to the species with 2n = 28, B. buxifolia and B. heterophylla (2n =56) grow in areas where the rainfall range is low. The opening of new habitats for colonization as a result of climatic change provides an ecological opportunity for the polyploids to exploit their inherent advantage.

Cytogenetics of Four Species of Genus <i>Berberis</i> L. (Berberidaceae Juss.) from the Western Himalayas

“…Fedorov 1969, Kumar andSubramanian 1986, Index to Plant Chromosome Numbers, web, etc.). However, the genus is monobasic, i.e., x = 14, as suggested earlier by Bottini et al (1999). Polyploidy is noted to be 8.18% compared to 6% as previously reported by Hong (1990) for species with only diploids known from India.…”

Relationships among Genome Size, Environmental Conditions and Geographical Distribution in Natural Populations of NW Patagonian Species of Berberis L. (Berberidaceae)

“…The genus Berberis shows two ploidy levels, namely diploids with 2n 28 and tetraploids with 2n 56 chromosomes (Bottini et al, 1997(Bottini et al, , 1999. The total DNA content does not show intraspeci®c variation, in contrast with the wide interspeci®c variation existing throughout the genus (Table 2, Fig.…”

“…The increase in repetitive DNA may play an important role in gene regulation, while gene duplication may enlarge the ecological amplitude through the acquisition of new genic functions (Levin and Funderberg, 1979). Increased ecological diversity and the opening of new habitats for colonization of xeric areas, as a result of climate changes, provide an opportunity for polyploids to exhibit their adaptive abilities and to contribute to the ®ght against deserts in Patagonia (Bottini et al, 1999). It is interesting to point out that the correlation with climate, especially the association of polyploids with dry conditions (B. heterophylla and several populations of B. buxifolia) are in accordance with Grime and Mowforth's theory (1982) in which phenology (the seasonal timing of shoot expansion) is the key phenomenon.…”

Observation on meiotic behavior in threeMahoniaspecies, with special reference to the intergeneric relationship ofMahoniaandBerberis

“…Only 6% of the 83 Berberis species examined showed a case of polyploidy, while the other 94% all showed a count of 2n = 2x = 28. BoTTINI et al (1999) examined the meiotic metaphase of 13 Berberis species, in which he found that, except for two tetraploid specie~ with 2n = 4x =56, other species all had a diploid number of 2n = 2x = 28. He also found that the chromosome configurations at metaphase were 1411, and that there was secondary association of two bivalents in the Berberis species studied at meiotic metaphase.…”