碩士 / 國立臺灣大學 / 生態學與演化生物學研究所 / 104 / Habitat alteration impacts the distribution of species and population dynamics through changing biotic or abiotic factors. Most studies have focused on the changes in abiotic factors, such as temperature, when considering the effect of habitat alteration on species distribution. The role of biotic factors, such as interspecific competition, remains largely unexplored. Furthermore, there are even fewer studies investigating the synergistic effects among abiotic, inter- and intraspecific factors on the distribution of species. Here, we used the burying beetle, Nicrophorus nepalensis, a widely distributed cooperatively breeding species, to study the ecological impact of habitat alteration on the distribution of species. Our study was conducted along two elevational gradients in the central cross-island highway of Taiwan, where the habitats on the west side are extensively altered but nature forests on the east side remain intact. Specifically, we test three alternative, but non-mutually exclusive, hypotheses: (1) “microclimate condition hypothesis”, which means that microclimate alteration in the habitat limits the reproduction of N. nepalensis; (2) “inter-specific competition hypothesis”, which argues that habitat alteration enhances the competitive ability of interspecific competitor, flies; and (3) the “Allee effect hypothesis”, which states that habitat alteration decreases the population density of N. nepalensis, which, in turn, impacts its competitive ability against the flies. Our results showed that, by comparing the microclimate data and group size of flies in natural forests along the two elevational gradients, we rejected the first two hypotheses because the microclimate conditions of the two elevational gradients were similar and the numbers of the flies on the east side were even larger than it was on the west side. Interestingly, we found that the group size was positively correlated with the population density of N. nepalensis, and the probability of successful breeding was positively correlated with the group size of N. nepalensis at the lower elevation. Also, we experimentally manipulated the population density by placing high density (three males and three females) and low density ( one male and one female) in the breeding boxes in the field at two gradients. We found that the probabilities of successful breeding were the same between the two gradients, where the high-density treatment had a higher successful rate than the low-density treatment, small group, supporting the Allee effect hypothesis. In conclusion, our experiment shows that habitat alteration negatively impacts the fitness of burying beetles and, thus, limits their elevational distribution through lowering their population density, which leads to Allee effect and weakens their interspecific competitive ability against flies. Our study, therefore, demonstrates that understanding the synergistic effect of biotic and abiotic factors is crucial for determining the ecological impacts of habitat alteration and conservation.
| Identifer | oai:union.ndltd.org:TW/104NTU05110014 |
| Date | January 2016 |
| Creators | Tsung-Wei Wang, 汪琮瑋 |
| Contributors | 沈聖峰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 47 |
Page generated in 0.0025 seconds