biological levels of organization.
hierachy of incompatabilities at each level of organization.
wild type [https://en.wikipedia.org/wiki/Wild_type], is salient, it was apparent however you are not aware of wild type, as in "not manipulated by humans." a product of alleles in naturally occuring environmental context.
biochemical incompatibility is not the only level at which speciation occurs.
also relative frequencies are considered.
when highest frequency of mating occurs between, wolves, and wolf coyote is an outlier, low frequency gene flow you are looking at the equilibrium between species separation and hybrid backcrossing.
there is a lot of in jargon, wrt science, thus if you dont understand right away, and someone leads you through a rabbit hole, you will hear a bunch of jargon popping up as if bullshit. but thats what happens when you dive in with out a primer. keep talking to biologists of differing fields and you will eventually understand the extent of brevity that occurs so as to avoid reiterating facts as basic as up and down or black and white.
biochemical, physiological, anatomical, behavioral, geophysical, geographical.
these are tiers of biological organization, and are interdependant.
gene mismatch, climate intolerance, mechanical union, stimulus/response, physical inaccessability, intraversable distance.
these are the speciation drivers that occur at these levels, respectively.
its not a digital phenomenon, its a statistical equilibrum, that is forced to occupy a new central tendency, as a result of environmental influence.
if you need more help regarding speciation it exists.