Species distributions are dependent on interactions with abiotic and biotic factors in the environment. Abiotic factors like temperature, moisture, and soil nutrients, along with biotic interactions within and between species, can all have strong influences on spatial distributions of plants and animals. Terrestrial Antarctic habitats are relatively simple and thus good systems to study ecological factors that drive species distributions and abundance. However, these environments are also sensitive to perturbation, and thus understanding the ecological drivers of species distribution is critical for predicting responses to environmental change. The Antarctic midge, Belgica antarctica, is the only endemic insect on the continent and has a patchy distribution along the Antarctic Peninsula. While its life history and physiology are well studied, factors that underlie variation in population density within its range are unknown. Previous work on Antarctic microfauna indicates that distribution over broad scales is primarily regulated by soil moisture, nitrogen content, and the presence of suitable plant life, but whether these patterns are true over smaller spatial scales has not been investigated. Here we sampled midges across five islands on the Antarctic Peninsula and tested a series of hypotheses to determine the relative influences of abiotic and biotic factors on midge abundance. While historical literature suggests that Antarctic organisms are limited by the abiotic environment, our best-supported hypothesis indicated that abundance is predicted by a combination of abiotic and biotic conditions. Our results are consistent with a growing body of literature that biotic interactions are more important in Antarctic ecosystems than historically appreciated.

物种分布取决于与环境中非生物和生物因素的相互作用。温度、湿度和土壤养分等非生物因素，以及物种内部和物种之间的生物相互作用，都会对动植物的空间分布产生强烈影响。南极陆地栖息地相对简单，因此是研究驱动物种分布和丰度的生态因素的良好系统。然而，这些环境对扰动也很敏感，因此了解物种分布的生态驱动因素对于预测对环境变化的响应至关重要。南极蠓（ Belgica antarctica ）是该大陆唯一的特有昆虫，沿南极半岛呈片状分布。虽然其生活史和生理学已得到充分研究，但其范围内种群密度变化的因素尚不清楚。先前对南极微型动物的研究表明，大尺度的分布主要受土壤湿度、氮含量和适宜植物生命的存在的调节，但这些模式在较小的空间尺度上是否成立尚未得到研究。在这里，我们对南极半岛五个岛屿上的蠓进行了采样，并测试了一系列假设，以确定非生物和生物因素对蠓丰度的相对影响。虽然历史文献表明南极生物受到非生物环境的限制，但我们最有力的假设表明，丰富度是由非生物和生物条件的组合预测的。我们的结果与越来越多的文献一致，即生物相互作用在南极生态系统中比历史上认识的更重要。