Mean family age and community phylogenetic structures of Taiwanese woody vegetation along elevation
| Autor: | Kenneth Chun-Chiang Huang, 黃駿鏹 |
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| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 The mechanisms of community assembly are a challenge to investigate due to the multi-level influences from both environmental and historical processes. However, analyzing the phylogenetic relationships of species in a community may provide some insights into how communities are formed and retained. Two leading hypotheses that explain species diversisty patterns along environmental gradients are the 1) Tropical Niche Conservatism (TNC) and 2) Out of Tropics (OOT) hypothesis. TNC predicts that as niches are temperature constrained, when temperature decreases along the altitude only certain adapted lineages can continuously diversify to temperate climate, the mean community clade age tend to be younger. In contrast, the OOT hypothesis signifies a rapid migration of randomly distributed lineages to cooler climates where they diversified slowly, therefore lacking younger lineages. Taiwan is a suitable model system for the observation of the assembly process due to its young geological age, diverse climatic conditions and steep elevation gradient. In this study, we focus on determining underlying mechanisms for the woody angiosperm of Taiwan. By analyzing more than 3000 vegetation community plots, we found that with decreasing temperatures toward higher elevation, phylogenetic relatedness within the woody angiosperm communities tend to decrease while the mean family age (MFA) peaks at mid elevations just before gymnosperm forests influence. This pattern is coherent with the OOT hypothesis and is further supported by findings that show MFA correlates to factors such as lowest minimum temperature of the coldest month. By applying phylogenetic methods to community distributions, our results tell us more about Taiwan’s community assembly mechanisms, providing new information about the biogeographical and evolutionary source of species in plant communities at different elevations. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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