Among the many species that grow in New Caledonia, the pitcher plant Nepenthes vieillardii (Nepenthaceae) has a high degree of morphological variation. In this study, we present the patterns of genetic differentiation of pitcher plant populations based on chloroplast DNA haplotype analysis using the sequences of five spacers. We analyzed 294 samples from 16 populations covering the entire range of the species, using 4660 bp of sequence. Our analysis identified 17 haplotypes, including one that is widely distributed across the islands, as well as regional and private haplotypes. The greatest haplotype diversity was detected on the eastern coast of the largest island and included several private haplotypes, while haplotype diversity was low in the southern plains region. The parsimony network analysis of the 17 haplotypes suggested that the genetic divergence is the result of long-term isolation of individual populations. Results from a spatial analysis of molecular variance and a cluster analysis suggest that the plants once covered the entire serpentine area of New Caledonia and that subsequent regional fragmentation resulted in the isolation of each population and significantly restricted seed flow. This isolation may have been an important factor in the development of the morphological and genetic variation among pitcher plants in New Caledonia.

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Our results highlight that spatiotemporal heterogeneity in the Japanese islands may play a significant role in the biogeographic history of Japanese endemic primroses. Contrasting evolutionary processes found in closely related species illustrate the effects of climatic niche evolution on species' diversification patterns.

Genetic and ecological evaluation are crucial in effective management of rare and endangered species, including those exhibiting complex breeding systems such as distyly.  We studied a threatened distylous herb Primula reinii in the Hakone volcano, central Japan, to obtain baseline information of reproductive and genetic status towards conservation.  In two representative populations inhabiting a central cone and somma of the volcano, population size, floral morph ratio, stigmatic pollen deposition, and fruit-set were measured.  Using microsatellite markers, we evaluated genetic diversity, structure and differentiation of populations.  Population bottlenecks and historical changes in population size were also estimated from genotype data.  We found significant deviation from equal morph ratios in the central cone population, which also exhibited skewed mating success together with a high frequency of pollination within the same morph.  These trends were not detected in the somma population.  From genetic insights, the central cone population showed slightly lower genetic diversity, whereas no significant deviation from Hardy-Weinberg equilibrium was found in either population.  The estimated moderate genetic differentiation and admixed genetic structure suggest recent lineage divergence and/or gene flow between populations.  While robust evidence for a recent bottleneck was not obtained in our analyses, a clear signature of historical population contraction was detected in the central cone population. Our findings suggest that the skewed morph ratio strongly influenced the reproduction of small and isolated populations in the short-term, highlighting the vulnerability of distylous plant populations under ongoing anthropogenic pressure.