Owing to tremendous complexity and diversity of microbiome communities, it has been challenging to comprehend and perceive the ecological processes regulating the microbiome community assembly from micro to macro scales. In macroecology, Vellend proposed that the four ecological processes such as selection, drift, dispersal, and mutation/speciation determine the patterns of ecological communities. Recently, there emerged a great interest in understanding the role of these processes in microbiome community ecology. A few studies have suggested that these processes interactively determine the patterns of microbiome diversity across environmental and biogeographic gradients. However, it largely remains untested to partition the relative effect size of these processes on microbiome diversity and functioning from micro- to macro-scales. Meanwhile, a very little know-how about the multifaceted impacts of global land use and climate changes on these processes makes it difficult to perceive their role in the generation and maintenance of microbiome ecological diversity and functioning. There is a pressing demand to develop, test, build, and apply new ecological hypotheses and theories with the help of ecostatistical and robust genomic techniques to understand the relative significance of different ecoevolutionary processes in microbiome functional community ecology in the time of global climate change and microbial diversity loss.