Is it also possible that elephants have enough awareness to notice who among them is more likely to be murdered by humans, and start selecting partners differently?
Of course there could be sexual selection at play! I would argue though, that form of selection will take at many generations to take hold where as genocide of a species happens in a single generation. Of course, the smaller the population, the faster sexual selection will take effect but it might be hard to disambiguate with other fitness factors.
Fwiw, a very similar thing happens during selection for bacterial resistance. You eliminate all the cells susceptible leaving a population of resistant cells. This population then grows to replace the previous generation. You could analogize this with the elephants. Small tusk and docile elephants have a "resistance" to being murdered by poachers. The poachers eliminate all the others and suddenly the population seems domesticated.
