Mary Shelley's Gothic novel, Frankenstein, is certainly a Victorian novel that concerns itself with Darwinism as Victor Frankenstein interferes with the evolutionary processes as developed by her contemporary, Charles Darwin. However, the creature is not malicious by birth, but molded by the malevolence of his environment. Thus Shelley's creature exemplifies the concept of Social Darwinism:
...social forces are of such a kind as to produce evolutionary progress through the natural conflicts between social groups. The best-adapted and most successful social groups survive these conflicts, raising the evolutionary level of society generally (the 'survival of the fittest')."
The creature exacts his revenge upon those close to Victor because his creator abandoned him, others are gratuitously cruel to him when he attempts charitable and friendly acts. When the creature and Victor meet at the end, the creature tells his maker that "evil became his good" only after all the cruelty dealt to him by society.
Many major Victorian poems and novels address the question of evolution. Among the most profound was Tennyson’s ‘In Memoriam’ which struggled with how we can live meaningful lives in light of evolution. In the poem, Tennyson is mourning the death of his friend Hallam against a background in which not only individuals but entire species die out (his inspiration was the work of Lyell on the geological record). Edmund Gosse’s father, as described in Father and Son, wrote a book that attempted to reconcile some parts of evolution with a literal reading of the Bible. Mrs. Humphrey Ward’s Robert Elsmere touches slightly upon evolution in its approach to crises of faith.
...and, of course, Frankenstein is absolutely not a Victorian novel, as Queen Victoria didn't ascend the throne until 1837, and the general consensus is that the Victorian age begins in 1830.
Yes, Frankenstein can definitely be seen to anticipate the Darwinian theory, which was certainly also anticipated by scattered scientific publications by, for instance, his mentor Huxley, but the problem is that the particular question I'm dealing with asks for literary texts that can be understood to respond to Darwin's 1859 Origin of the Species, which Shelley's 1818 can't!