Étude cyto-écologique de quatre populations de Claytonia caroliniana var. caroliniana au Québec

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Abstract
The cytology and ecology of four Québec populations of Claytonia caroliniana var. caroliniana, each one coming from a different phytosociological climax domain, have been studied. The plants from Mt. Logan (subalpine zone) were stable (n = 8 or 2n = 16, the usual chromosome number of the species) but three other populations (maple forest domains) have shown various proportions (10–50%) of abnormal chromosome numbers: n = 9, 10, 11, 15, 19, 20 and 2n = 17, 25. These numbers could be explained (1) by the formation of diploid gametes, (2) by the arising of triploid individuals, and (3) by the presence of B chromosomes. The percentage of plants with anomalies is parallel but smaller when tubers are examined instead of the flowers. This suggests a disturbing influence of environmental or genetic factors on scapes, flower development, or sporogenesis. The plants with abnormal chromosome numbers observed in the samples, seem to be occasional cytotypes rather than representatives of actual chromosomal races. Furthermore, there are apparently no morphological characters permitting their identification or the segregation of the various populations that have been studied from different environments. The frequencies of anomalies in the flowers seems to be related to the stations (χ2 = 8,75, df = 3). Correlation tests also show that the drainage and rainfall in April and May could be eventually connected (r = 1,000, α = 0,05) to the chromosomal anomalies and to the cytological evolution of the populations, as it possibly affects the sporogenesis which takes place when the scapes reach the soil surface. Such causative correlations are evidently extremely hypothetical because the number of sampling points is too small; more cytological and ecological data and (or) experimental evidence still remain to be collected. Nevertheless, these observations demonstrate that C. caroliniana is undergoing cytological variations in the northeastern part of its area and behaves similarly to C. virginica.