I have not seen A:R yet (nor quite sure when I will, I hope to be "in the 'big city'" with time to spare at some point, but my cinematic roullette may land upon something else I'm interested in that's more conveniently timed for the next time I've got that window...). So no spoilers from me. But being an early Alien 'fan' (not necessarily kept up with all developments in canon/fanon over time, tbough), my headcanon was always pretty much of the Komodo Dragon style procreation (mixed with the context of a social-insect colony).
i.e. parthogenesis by a female (ZW-chromosomes, in Komodos) creates an individual with a 'male' complement of sex chromosomes (Z-eggs double to viable ZZs, W-eggs become infertile WWs), so a lone female washed up on an island/planet then has males from which to breed 'normally' (ZZxZW => more ZZ and ZWs).
Although probably standard insectile haplodiploidy was always intended as the inspiration. The disadvantages of relying upon that system (a lone non-queen would be unable to start any dynastic nest) could be accounted for by a few tweaks. A lone diploid worker (female, non-queen) does eventually get the opportunity to get any normally haploid eggs (that would produce male drones) fertilised through a 'lone-ness trigger' instead of requiring deliberate and explicit royal-jelly application by her 'queen mother' to create her as a diploid queen already. And/or a lone-drone (haploid, male) might eventually be able to perform a partial-meiosis not just of its usual haploid sperm but of a rare doubled-up diploid egg (without the homogametic element necessary at all, unlike the XY or ZW systems) that effectively gives the stranded male 'insect' its necessary female as opposed to the stranded female dragon its necessary male.
(The fact that the xenomorph lifecycle requires stages of obligate parasitism is the main limit to its reproduction, assuming that it has both a sexual and asexual reproductive possibilities so easily available that it almost doesn't matter how isolated any individual of its species might be. And possibly for how improbably long it might be.)
There are other real-world (earthly) variations upon the theme to consider, through unguided evolutionz in which every system has found itself to be at least vaguely effective for the circumstances, or else it would not be around to be observed. Nor has any system been so ruthlessly efficient (or over-productive) as to dominate the ecosphere (though counting by mass or numbers, you could suggest that some variations are 'dominant', including boring old asexual budding from countless micro-organisms. But then none of the 'earthly' species were actually designed from the very baseline of their molecular biology,[citation needed] whereas it is now established that the Alien lifeform was created by (over-reaching?) progenitors with expertise at least as great as their hubris and/or self-destructive nihilism.
(The established canon/fanon in the '80s, with just the first one or two big-screen productions and some comic-book releases that may or may not have been official, was that the Aliens were just one species of many that evolved an ecological niche upon a particularly nasty planet within a system of various other species at least as deadly and dominant as themselves. Then some spacefaring race (the 'Navigator' one) failed their biosecurity procedures and managed to establish a lineage of hitch-hiking Aliens that had none of their traditional (and natural) competitors around to keep them in check. Or maybe (as per later cross-over) it was a 'deliberate' relocation attempt by the sport-hunters that were the Predator race, that may or may not have gotten out of hand. Not entirely sure that either of these theories aren't at least partially compatible with the new continuity established well after Alien³, what with reboots and re-envisioned back-stories where the Navigator is not quite as an unwitting innocent as originally assumed. And is AvP even considered canon any more?)
As with Jurrasic Park, one can very easily treat the moral as "life finds a way". (Depending upon your perspective, you could say this for either side of the Human/Alien conflict!) There are actually a number of shared tropes between the two franchises (though I know who I'd bet on, in any crossover story). That's whether you go with the presumed Deathworld Origin of the early Alien films, the reckless reseeding of the AvP-era shared universe or the Promethean revelation (though, with its messianic message regarding even the seeding of life on Earth, we humans are at least as much a creation of the progenitors as the alien xenomorphs).