Conservation Ecology Of Impatiens Hainanensis (Balsaminaceae),Endemic Species In Hainan Island

Impatiens L. which belongs to the family Balsaminaceae is both one of the super-large genera of extant angiosperms, and a large genus with high differentiation and significant diversification. The geographical distribution of Impatiens has extremely obvious regionality and endemic phenomenon since Impatiens plants are extremely strict with their habitats. The majority species of Impatiens are narrow endemic to China or some province in China, and this endemic phenomenon is more significant in the limestone area of South and Southwest China. However, it has lacked in-depth research on the relationship of these species with limestone matrix, especially comprehensive research on aspects of population structure, heterogeneity of habitat, genetic structure, cytology, physiology, ecology, and germplasm preservation. Therefore, there is still no well perspective for the endemic mechanism and adaptation countermeasure of these endemic plants.Impatiens hainanensis Y. L. Chen which can be seen at bare limestone gap of the summit only distributes in the limestone area of Hainan, including places such as Changjiang, Dongfang, Baisha, this means that Impatiens hainanensis is an obligate endemic plant to the limestone area of these places. The habitat of Impatiens hainanensis has been destructed seriously because of the tradition of slash-and-burn cultivation and gathering herbs among local ethnic minorities. According to endangered species evaluation standards of IUCN, Impatiens hainanensis is in the endangered state now, and is listed as one of Hainan provincial key protected wild plants.The research on conservation ecology of Impatiens hainanensis was discussed in this study, involving community ecology, breeding ecology and conservation genetics during its peculiar process of being endangered, in order to understand the internal adaptation mechanism of the endemic limestone plant to its habitat and analyze the main causes for being endemic and endangered. Furthermore, by trying to establish a system based on tissue culture propagation, this study provided scientific decision bases for effective germplasm resources preservation and formulating scientific and reasonable protection strategy.The research result and innovative content show as the following:1. Population ecologyThe distribution pattern of community vegetation for Impatiens hainanensis, was under to reveal the reasonable environmental interpretation. At the same time, the ecological relationship between population size and species diversity under different associations are also investigated. The results showed that:(1) Consistent with the results of DCA sorting, the16samples were divided into four types of association by TWINSPAN classification.(2) DCA sorting reflected the relationship between each association type and environmental factor, the first ordination axes mainly indicated the change of altitude gradient, and the second ordination axes mainly implied the change of canopy density gradient.(3) Both species diversity index and richness index differed not only from associations but also in layers. This endemic species, Impatiens hainanensis, cluster in different community was closely related to the formation of the association and environmental factors. In addition, the altitude is environmental factor that affect the distribution pattern and species diversity.(4) Population sizes varied with seedling regeneration ability under different community structure, which indicated that we should take appropriate measures to protect different populations of Impatiens hainanensis.in Hainan Island.2. Pollination biologyThe flowering biological characteristics and floral phenology, floral structure, pollen viability and stigma activity, floral visitors and their behavior, and the breeding system were observed and determined. The results shows that it last25.2d from flower bud germination to fade; the life span of one flower was4.10d; the male stage and female stage of flowering were3.95d and0.95d respectively; the population flowering peak was in early August, and which in the high altitude population was latter; the pollen viability of a single flower was highest on the second flowering day in low and middle altitude populations. But in high altitude population, it was highest on the first flowering day and lower than other two populations in different flowering days; the stigma activity raised as the flowering time went on, but which in high altitude population was lower than other two populations in different flowering days. The main pollinators were Amegilla leptocoma and Amegilla zonata, and A. leptocoma was the main visitor in low and middle altitude populations while high altitude population was A. zonata; there is no automatic self-pollination and apomixis phenomenon in I. hainanensis, and hand-pollination increased the fruit set (75-90%), which was lower in the natural situation (40-60%), especially in the high altitude population which endured the stronger limitation of pollination. Therefore, when we proceed the work of Impatiens hainanensis conservation, we should also pay attention to the protection of habitats and effective pollinators of Impatiens hainanensis, in order to promote effective pollinators in the exchanges among different altitude populations, and ensure pollen and seeds flows between different populations, to maintain the population genetic diversity of and effective population size of Impatiens hainanensis.3. Population geneticsISSR molecular marker technology was used to analysis the genetic diversity of Impatiens hainanensis population and compared the effects of three elevation gradients on population genetic structure. The results indicated that:13ISSR primers amplification results showed that the polymorphism loci percentage is97.7%; AMOVA analysis indicated that the variation of Impatiens hainanensis population occurred mainly within populations (92%) and limitedly between populations (8%); Altitude populations in the most abundant genetic diversity; The high altitude population genetic diversity is low; genetic distance and geographic distance of population showed a significantly high specificity. Analysis shows that altitude is the important factors that affect the population gene flow, high altitude populations can be spread pollen and seeds to the low altitude populations, the similar activity of low altitude populations to high altitude populations is more difficult, the main reason for the small number of Impatiens hainanensis plants came from its habitat. So in the future protection work, we should put special emphasis on the habitat protection and avoid the destruction of the human factors.4. Micropropagation in scale by tissue cultureDeveloping an effective artificial breeding system is one of the important methods to promote the endangered species protection and reasonable development and utilization of wild resources. Due to human activity and habitat destruction, the population and distribution area of Impatiens hainanensis Y. L. Chen which is endemic to Hainan have showed decreasing tendency in recent years, In this study, seeds, young leaves and lateral buds of Impatiens hainanensis were explants for in vitro culture. The results showed that optimized media as follows:(1) The medium for seed germination: Hyponex No.13.0g·L-1+Peptone1.0g·L-1+Coconut Milk CM100ml·L-1;(2) The medium for leaf callus induction is MS+6-BA3.0mg·L-1+NAA0.1mg·L-1;(3) The differential medium for callus induction is MS+6-BA2.0mg·L-1+NAA0.5mg·L-1;(4) The medium for axillary buds induction is MS+6-BA1.0mg·L-1+NAA0.2mg·L-1;(5) The proliferation medium for multiple shoots is MS+6-BA2.0mg·L-1+NAA0.5mg·L-1;(6) The medium for root induction is MS+NAA0.5mg·L"1.