Evolutionary processes are by which organisms have evolved from a common ancestor. Through natural selection, mutations, adaptation, and genetic drift, certain genes are passed on, changed, or eliminated. Evolution is a change in species over time; this change is caused by the variant frequency of an allele or alleles in a population. The changes in these genes have created diverse species and sometimes altogether new species.
Natural creatures are named so due the major factor at play for their speciation: natural selection. Within each species population, there are differences in genetic makeup. These differences in traits can result in organisms within the same species varying in color, size, or behavior. In the process of natural selection, the organisms with the traits are most conducive to survival live to pass on those traits. The demands on a population to provide enough resources dictate that not all members of the population will survive. A species evolves, through its members that “fit” the environment. Changes in the environment separating a species members, members adapting to fulfil a new role in the environment, or selecting mating partners based on certain criteria can lead to the formation of new descendant species.
Faye are an interesting case in that the larger driving forces for their traits is largely due to their origins. All faye share their origins to the natural alchemy of the early conditions of Kaf. As the world was beginning to develop its background field of magic and its own parallel spirit realm, the psychic echoes or “souls” of the deceased animals and people of the Earth introduced by the Djinn was the major factor behind these changes. During this process, the souls merged the animals and peoples defining traits with aspects and instinctual connections to the physical phenomena and processes of nature to create these creatures from modified animals and magifauna or the environment itself. The fact that most faye have the capacity for human like thought and variations of a humanoid body plan is thought to be due to the humans producing more psychic energy than any other animal in the Akasha. Once the events that set these fundamental features subsided, natural selection was the major factor actively affecting faye species afterwards but the influence of the human mind and body on faye as a whole will likely remain.
Spirits species are for the most part, bound to their forms and functions due to their extradimensional makeup. Spirits adapt by temporary transformations into a new state then revert back instead of gradual change inherent in regular speciation. For the longest time, the only spirits were angels and jinn. When creating the Archeus of Kaf, new kinds of spirits were by-products of the process. These spirits started out as blank slates but their connection to aspects of the material world drove the change into the diverse types of spirits there are today.