That's quite a lot of diversity, especially among dwarves! What's the reason for that?
The various iterations of the dwarven government have kept the different castes separate from each other and practiced selective breeding for a very long time. Some of the crystal-based technology they use has also contributed to speeding up the divergence.
As for the genesis of all the different races—a few are the result of specific events (the avian shapeshifters, for example, were originally humans that got altered by a magical artifact), but in general, there isn't a general consensus. Everybody has their own myth about where they came from, of course, but the truth of the matter will probably turn out to be a major plot point eventually.
Also, what do you mean by "somebody had a Khajiit-ish species of cat people at one point"? Is this a collaborative project?
Oh! Ha. I thought I mentioned that in my first post, but it looks like I spaced it—this is all set in the Domhantir collaborative worldbuilding project. It's been going for a couple of years now, but it isn't terribly active.
How advanced are the races?
It's a little hard to compare them to Earth civilizations, because alternate physics/magic results in divergent paths of advancement. But compared to each other:
The Talambrian Empire and the various elven nations from Aetherae are all very advanced, boasting several large city centers and rich technological systems. Neither has developed steam power or electricity, but Talambar benefits from a powerful runic magic system while Aetherae is home to a very developed school of song-based magic, both of which play heavy roles in innovation and keeping people comfortable. Both have a long philosophical tradition, although Talambar's is focused mostly on politics and strategy while Aetherae's is more diverse.
Atherom is a smaller and younger human nation based off of a large isle, whose naval technology ranks among the best in the world. The Thromesians utilize a sort of hybrid magic system drawn from elements of elven songspell and old crafts from pre-unification Talambrian tribes. Their political and social philosophy is similarly based on both Talambian and Aetherean elements, but with a much stronger emphasis on freedom and individualism. The nation has also been heavily influenced by the Church of the Nineteenth Gate.
Quamnis (the tehuanti's home continent) is on the whole much less advanced. There is one major city center which appears to be very old, and there are other ancient ruins on the continent that suggest the tehuanti were once much more advanced than they are now. Currently, though, the majority of the population lives spread out between small villages in the rainforest. One of the tehuanti's most advanced technologies is a very old dance-based magic system, through which some advanced practitioners can achieve strikingly powerful effects. Practitioners of the art are much rarer than those of the Talambrian or Aetherean systems, however.
The dwarves have their own magic system which is primarily crystal based, and of all the races, they have the most advanced understanding of mathematics. Their culture is dominated by a very old doctrine of aesthetics, ethics, and social engineering (and the different ways that doctrine has been interpreted over the generations). True to the trope, they are skilled architects, metallurgists, and mechanics. However, in the wake of a major war a few centuries back, they have remained mostly isolated, trading with a few trusted Thromesian and Talambrian traders without leaving their own shores.
Alright, I won't ask much about those other guys if that's not your department, but in what ways has the speciation of dwarves manifested itself?
No worries! I'm the main contributer for the feayr, the tehuanti, and the dwarves, and I've done a lot of work on the Talambrians, so my department is pretty broad.
There are (at the moment) four castes—the servant caste, the soldier caste, the artisan caste, and the noble caste.
The servant caste is charged with agriculture, mining, and quarrying, as well as some menial labor. It is the most populous caste, and its members are physically the largest; they tend to be a little bigger than the average human. They have very sharp hearing and a relatively developed sense of smell, as well as very good night vision, but because almost invariably they spend their entire lives below ground, they are very sensitive to bright light, and their skin cannot stand sunlight. Dispositionally, they have been selected for submissiveness and slow-wittedness. I plan on adding some notable linguistic differences to the servant-tongue dialect of the dwarven language, such as some restrictions on recursion, but I haven't worked them all out yet.
Soldier caste members are almost as big in stature as servants. They are much more resilient, with very thick skin and a distinct bone structure—their skulls and ribs are visibly thicker, and they have a set of bony plates under the skin in their abdomen which shields their major organs at the expense of some mobility. Their limb structure is also modified, giving them greater leaping and striking power. They are less susceptible to disease and heal quickly, although they are vulnerable to berserker rages with a sufficient hit of adrenaline.
The artisan class is charged with most manufacturing work and academic study. Their skin is a little less thick than soldiers', and their bones are very dense (though not structurally as distinct as soldiers' are), but they are shorter and not naturally as strong. Soldiers and artisans can sometimes interbreed, but the offspring is always sterile.
The noble class is the most diminutive of the castes, and the one with which foreigners are most familiar. Nobles are charged with trading, administrative tasks, and government roles. They are reproductively compatible with artisans, but not with soldiers or servants. Along with the artisans they are the most intelligent of the castes.
Also, what is the material culture of the feayr like? Do they wear clothes in either form?
The feayr do not often wear very much clothing due to shapeshifting complications, since only fabric that is woven from the hair of the wearer will change with the shift. Once individuals come of age, females will use this material for breast bindings during whelping season, and both genders wear a breechcloth throughout the year.
Otherwise clothing is not very common. Children, prior to undergoing the naming rite, usually wear nothing at all, and adults will only wear additional clothing if they have to work in human shape out in the cold for an extended period of time. Certain ornamental pieces may be worn for ceremonial purposes, but scented oils are more common than pieces of clothing for this. (In general, ritual and ornamental regalia is much more olfactory-focused than visual.)
In terms of general material culture, HW feayr actively exchange goods like tools, crafts, scents, and food (though special rules apply in that last case), but the economy is based on gift-giving and social capital. The pack is structured upon a web of stance
relations, where every member is in either a leading
relationship with each other member, with a few exceptions. (These relationships are manifested in the language as well, which is one of my favorite features.) Gift-giving increases the social standing of the giver in relation to her stance toward the recipient.
In mated pairs, possessions and gift-giving/receiving are managed by the female.
Have you read A Fire Upon the Deep or The Children of the Sky? They feature a race of aliens who closely resemble dogs with a preindustrial level of development, and you might get a sense of how sentient canids would behave. Also, they're very good books.
I had not heard of them! I'll have to make a library raid—thanks for the rec!