For most of science astronomy, geology, evolutionary descent of species data are robustly available, in what are by definition ecologically valid environments, and they can be gathered.
That species are a product of evolutionary descent was uncontroversial to Fodor, an avowed atheist; that the mechanism guiding the process was adaptation via a competition for survival — this, Fodor believed, had to be wrong.
Feil, E. J., Li, B. C., Aanensen, D. M., Hanage, W. P. & Spratt, B. G. eBURST: inferring patterns of evolutionary descent among clusters of related bacterial genotypes from multilocus sequence typing data.
Darwin made extensive use of comparative anatomy in advancing his theory, and it in turn revolutionized the field by explaining the structural differences between species as arising out of their evolutionary descent by natural selection from a common ancestor.
It never occurred to Tyson or his contemporaries, who believed that all animals had been created independently in their current image, that humans, apes, and monkeys were connected by common evolutionary descent.
Since the publication in 1859 of Charles Darwin's On the Origin of Species by Means of Natural Selection, however, taxonomy has been based on the accepted propositions of evolutionary descent and relationship.
Why did early biologists depict evolutionary descent in tree images?
To assert that ancestors are hypothetical is to assert that evolutionary descent itself is hypothetical.
Thus there are two general processes at work in evolutionary descent.
Yet, they are not meant to represent evolutionary descent (Agassiz rejected evolution).
The shape of the teeth is related to the animal's food, as well as its evolutionary descent.
