Mcaroecological Study On Ant Diversity In China

To explore the spatial patterns and the underlying mechanisms of species diversity is the key research topic in ecology and biogeography. As with increasing human activities and risk from global climate change, biodiversity is facing severe challenges. The researchers have proposed many theories and hypotheses to explain species diversity patterns. However, the spatial patterns and mechanisms of species diversity in China still lack of comprehensive understanding. Many ecologists believe that geological history and phylogeny can partly explain the species diversity patterns, while the current environments are still the main factors driving spatial diversity patterns. China is a large country, with evident climate gradient, large altitude gradient, various types of ecological system, and contains almost all the vegetation types from desert to rain forest. Therefore, China gives birth to the rich diversity of plants and animals. This makes China greatly suitable for testing the relationships between species richness and environment.Ants play an important role in diverse ecosystems, since they possess high biomass, wide distribution, soil improving, plant pollination and pest control. Ants are highly sensitive to environment change, so many ecologists take ants as an ideal group for macroeclogical research.In this paper, I collected the information of ant distribution at provincial scale, and ant richness and body size databases in northwest Yunnan and southeast Tibetan at community scale. By integrating environmental information such as climate and altitude, we analyzed the relationships between ant diversity and environmental factors, Variance partitioning and hierarchical partitioning were used to determine the relative importance of each environmental factor in shaping ant diversity. This thesis aims to answer the following questions:(1) on a regional/provincial scale, how are ant richness and beta diversity related with environmental factors?(2) along the altitudinal gradient, how are ant richness and mean body length correlated with environmental factors? The conclusion is as follows:At the provincial level, ant species richness is negatively correlated with latitude, but there is no significant linear relationship with longitude. The hotspots of species richness are mainly concentrated in the southern provinces of China. Ant richness is low in the north, the northwest arid region and the north of the Tibet Plateau(Qinghai). Regardless of the taxonomic level(species or genus), temperature has the highest impact on the distribution pattern of ant species richness. According to the results, seasonal factor is also an important predictor, accounting for 65.1% of the total variance of genus richness, and 52.8% of the total variance of species richness.At the provincial scale, ant beta diversity is mainly influenced by the environment, that is, the niche limitation is greater than the dispersal limitation. To a certain extent, this explains why the ants exist in most parts of the world. Maybe due to the Last Glacial has a great impact on the North American region, the species has not yet reached equilibrium with the climate, therefore the animals and plants in North America are mainly affected by spatial distance. The impact of the glaciation on China is minor, and the climate and species distribution are relatively balanced. Therefore, the species distribution is affected by the ecological niche. The climate factor of average temperature of the coldest month(TEMmin) and actual evaporation have great influence on ant beta diversity. The former is one of the strongly limited factors, and its change is a challenge to the physiological function of ants. The latter mechanism is explained as: the individual of the ant with small size, the evaporation is more likely to cause its dehydration, or even to death.Along the altitude gradient, ant species richness decreases significantly. According to the results of variance decomposition and multi-level variance decomposition, energy has a great impact on ant richness pattern, which is similar to the results obtained at the provincial level. The mechanism is interpreted as: at low altitudes, the higher ambient energy, the higher net primary productivity(NPP), which increases the biomass in the region, provides more food for ants, and finally leads to the expansion of the region's species population size(population size). In the high altitude area, because of the shortage of food resources and low temperature slow ant metabolism, prolong its generation time, and ultimately lead to the rate of species evolution and species diversity.Along the elevation gradient, with the increase of altitude, the mean body length of ants becomes larger, which conform to the Bergmann‘s rule and is consistent to the results of previous studies. At lower altitude, the temperature is higher, which leads to the faster metabolic rate, reproductive organs of fast development, early maturity, short life cycle and smaller size. While at high altitudes, less resources and lower temperature cause higher mortality rate. In order to survive, ants need more food and resources. Meanwhile, the number of other species in the high altitude area also decreased, which also reduced the number of natural enemies of ants at the same time. Based on the life history trade-off hypothesis, the decrease of the predator will increase the size of the prey. Because of the high altitude, ant needs to take a long hibernation. In order to avoid death during hibernation, increasing body size is beneficial to the improvement of ant survival possibility.