Nabokov as a Darwin doubter

My interest in butterflies extends no more than a casual acknowledgement of their beauty when I see one, so I usually don’t feel much when reading Nabokov’s writings about butterflies, but this passage from Speak, Memory is interesting: 

“The mysteries of mimicry had a special attraction for me. Its phenomena showed an artistic perfection usually associated with man-wrought things. Consider the imitation of oozing poison by bubblelike macules on a wing (complete with pseudo-refraction) or by glossy yellow knobs on a chrysalis (“Don’t eat me–I have already been squashed, sampled and rejected”). Consider the tricks of an acrobatic caterpillar (of the Lobster Moth) which in infancy looks like bird’s dung, but after molting develops scrabbly hymenopteroid appendages and baroque characteristics, allowing the extraordinary fellow to play two parts at once (like the actor in Oriental shows who becomes a pair of intertwisted wrestlers): that of a writhing larva and that of a big ant seemingly harrowing it. When a certain moth resembles a certain wasp in shape and color, it also walks and moves its antennae in a waspish, unmothlike manner. When a butterfly has to look like a leaf, not only are all the details of a leaf beautifully rendered but markings mimicking grub-bored holes are generously thrown in. “Natural Selection,” in the Darwinian sense, could not explain the miraculous coincidence of imitative aspect and imitative behavior, nor could one appeal to the theory of “the struggle for life” when a protective device was carried to a point of mimetic subtlety, exuberance, and luxury far in excess of a predator’s power of appreciation. I discovered in nature the nonutilitarian delights that I sought in art. Both were a form of magic, both were a game of intricate enchantment and deception.” 

I came across this essay, which elaborates on and contextualises Nabokov’s “anti-Darwinian stance”: 
http://www.hcs.harvard.edu/tract/nabokov.html
There are some valid points, though the author of the essay also writes: 

“Notably, Nabokov was consistently opposed to organized religion; he was also, however, undeniably concerned with the problem of death. One might therefore contend that his skepticism of Darwinism was fostered, on some level, as a knee-jerk defense of the prospect of immortality.” 

That to me doesn’t make much sense. All (major) artists are concerned with death and the question of what happens after death, if anything. Nabokov has never struck me as being anywhere near religious (not just opposed to organised religion), nor have I ever got the impression that he believes in immortality, even if he sometimes mentions ghosts in his works. 
To be honest, I’m not even sure that Nabokov’s really anti-Darwinian, or believed in intelligent design rather than natural selection as someone else seems to suggest. Does anyone know his views? The way it appears to me is that, perhaps he was against natural selection and the theory of evolution altogether, but it’s also possible that he saw some validity in Darwin’s idea of natural selection but it couldn’t explain everything, such as the subtle mimicry in butterflies. 
Here is the final paragraph of the essay: 

“Boyd, Pyle and Zimmer all address the question of whether Nabokov, if privy to the full burden of proof now available in support of natural selection, would accept the Darwinian model as true. The general consensus is affirmative. Perhaps the next question to ask is how this conversion, by forcing a complete overhaul of Nabokov’s natural views, could have shaped his later fiction. Nabokov’s artistic precepts and staple themes are of course compelling enough to stand on their own, but one wonders to what extent a gloss of Darwinian utilitarianism might have altered the author’s basic literary sensibilities.”

Note: “the author’s basic literary sensibilities”. I don’t even know what that means.