Ohara, Masashi , Narumi, Tadashi , Nishizawa, Miyuki .
Variation of reproductive modes and population genetic structures of a monocarpic perennial herb, Caridocriunm cordatum, in relation to habitat fragmentation.
Reproductive systems are recognized to have profound influence on the extent and structure of genetic variation in plant populations. To investigate the sptio-temporal variation in the reproductive modes (sexual and vegetative reproduction) and population genetic structures of a monocarpic perennial herb, Caridocrium cordatum (liliaceae), we selected a variety of habitats (e.g., large forest area including primeval forest, small fragmented secondary forest and so on) around Sapporo City, Japan. We conducted breeding experiments, monitored the fate and growth of marked individuals for 3 years, and also analyzed the spatio-temporal genetic variation of flowering plants within the populations using allozyme variation. Plants emasculated prior to anthesis produced mature fruits in all populations examined. However, the seed production was significantly lower at the small fragmented populations possibly due to low availability of pollinators and subsequent pollen limitation. At these fragmented populations, the mature flowering plants tended to more depend on vegetative reproduction for their recruitments, because they only can produce flower once in their lifetime. Genetic diversity using samples from mature flowering plants in each population was lower at the small fragmented populations than the large populations. In addition, although genotypic compositions in the fragmented populations were more or less similar during thee years, the dominant genotypes was temporally and spatially changed every year in large populations. The present study presents that the reproductive features of C. cordatum could be altered under various environmental condition such as habitat fragmentation and those changes considerably affect the population genetic structures and vice versa.
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1 - Hokkaido University, Faculty of Environmental Earth Science, , Sapporo, 060-0810, Japan
Presentation Type: Oral Paper:Papers for Sections
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 2:45 PM